Quality of Selected Fruits and Vegetables of North America 9780841206625, 9780841208469, 0-8412-0662-7

Table of contents :
Title Page......Page 1
Half Title Page......Page 3
Copyright......Page 4
ACS Symposium Series......Page 5
FOREWORD......Page 6
PdftkEmptyString......Page 0
PREFACE......Page 7
Raisin Grapes......Page 8
Table Grapes......Page 9
Wine Grapes......Page 11
Factors Influencing Quality in Grapes......Page 13
Abstract......Page 15
Literature Cited......Page 16
THE ODOR OF LABRUSCA GRAPES......Page 17
METHYL ANTHRANILATE......Page 18
FOXINESS......Page 19
COTTON CANDY......Page 21
LITERATURE CITED......Page 25
3 Quality Characteristics of Muscadine Grape Products......Page 26
Literature Cited......Page 31
Isolation of Volatile Oils.......Page 33
Capillary GLC-Mass Spectral (GLC-MS) Analysis.......Page 34
Raisin Volatiles.......Page 35
Fig Volatiles.......Page 39
Fermented Figs and Drosophila Attraction.......Page 44
LITERATURE CITED......Page 45
5 Flavonoids, Mutagens, and Citrus......Page 46
The Salmonella test for mutagenicity......Page 47
Behavior of flavonoids in the Salmonella test......Page 48
Flavonol occurrence and metabolism......Page 53
Feeding studies......Page 56
Flavonoids in Citrus......Page 58
Are flavonols a menace?......Page 59
LITERATURE CITED......Page 60
6 Apple Quality Characteristics as Related to Various Processed Products......Page 63
Apple Characteristics......Page 64
Quality Factors Important to Different Processed Products......Page 69
Literature Cited......Page 78
7 Establishing Criteria for Determining the Authenticity of Fruit Juice Concentrates......Page 79
Free Sugars and Sorbitol......Page 80
Nonvolatile Acids......Page 84
Free Amino Acids......Page 88
Anthocyanin Pigments and Other Secondary Plant Metabolites......Page 92
Abstract......Page 93
Literature Cited......Page 94
8 The Role of Humidity, Temperature, and Atmospheric Composition in Maintaining Vegetable Quality During Storage......Page 96
Materials and Methods......Page 97
Results and Discussion......Page 98
Conclusions and Summary......Page 104
Literature Cited......Page 107
9 The Improvement of Flavor in a Program of Carrot Genetics and Breeding......Page 109
Perspective of Quality in U.S. Carrot Production and Improvement......Page 110
Steps in the Improvement of Carrot Quality......Page 111
Current Status and Future Prospects for Improvement of Carrot Culinary Quality......Page 115
Literature Cited......Page 117
Floral Hop Aroma/Taste......Page 119
"Kettle Hop" or "Noble Hop" Aroma/Taste......Page 122
Literature Cited......Page 127
11 Volatile Constituents of Pumpkins......Page 128
Separation and Identification......Page 129
RESULTS AND DISCUSSION......Page 130
LITERATURE CITED......Page 135
12 Volatiles from Red Pepper (Capsicum spp.)......Page 136
Experimental......Page 137
Results and Discussion......Page 139
Literature Cited......Page 144
13 Peanut Quality: Its Relationship to Volatile Compounds−A Review......Page 146
Off-Flavor Due to High Temperature Curing......Page 147
Normal Raw Peanut Flavor and Other Factors Which Affects Its Volatile Profile......Page 148
Enzymic Origin of Raw Peanut Flavor......Page 150
Characteristics of Peanut Lipoxygenase......Page 153
Roasted Peanut Flavor and Factors Which Affect Its Quality......Page 155
Research Areas of the Future in Peanut Quality......Page 156
Literature Cited......Page 157
Flavor Precursors......Page 161
Carbonyls......Page 163
Analytical Aspects......Page 164
Sensory Attributes of Roasted Peanuts......Page 166
Contribution of Newly Identified Compounds to Peanut Flavor......Page 171
Correlation of Instrumental and Sensory Data......Page 174
Abstract......Page 177
Literature Cited......Page 178
15 Comparison of the Food Value of Immature, Mature, and Germinated Soybeans......Page 180
Availability and Consumption Patterns of Soy Proteins......Page 181
Food Value of Soybeans with Respect to Maturity......Page 183
Antinutritional Factors and Protein Quality of Soybeans with Respect to Maturity......Page 189
Conclusions......Page 203
Literature Cited......Page 205
16 Lipid Oxidation in Fruits and Vegetables......Page 210
Formation of Carbonyls and Oxoacids by Chemical Reactions......Page 211
Formation of Carbonyls and Oxoacids in Vegetables and Cereals......Page 217
Formation of C8- and C10- (C-11) -Components in Edible Mushrooms (Agaricus campestris)......Page 224
Literature Cited......Page 228
Acknowledgements......Page 229
C......Page 230
G......Page 231
N......Page 232
R......Page 233
T......Page 234
W......Page 235

Citation preview

Quality of Selected Fruits and Vegetables of North America

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

Quality of Selected Fruits and Vegetables of North America Roy Teranishi, EDITOR

U.S. Department of Agriculture Heriberto Barrera-Benitez, EDITOR Comision SARH

Based on a symposium sponsored by the Division of Agricultural and Food Chemistry at the Second Chemical Congress of the North American Continent (180th ACS National Meeting), Las Vegas, Nevada, August 24-29, 1980. ACS SYMPOSIUM SERIES 170

AMERICAN CHEMICAL SOCIETY WASHINGTON, D. C.

1981

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

Library of Congress CIP Data Quality of selected fruits and vegetables of North America. (ACS symposium series, ISSN 0097-6156; 170) Mostly papers presented at the Symposium on Quality of Fruits and Vegetables of North America, held during the second Chemical American Continent, which include tional American Chemical Societ Includes bibliographies and index. 1. Fruit—Quality—Congresses. 2. Vegetables—Quality—Congresses. 3. Fruit—Composition—Congresses. 4. Vegetables—Composition—Congresses. 5. Fruit— North America—Quality—Congresses. 6. Vegetables— North America—Quality—Congresses. I. Teranishi, Roy, 1922. II. Barrera-Benitez Heriberto, 1939. III. American Chemical Society. Division of Agricultural and Food Chemistry. IV. Chemical Congress of the North American Continent (2nd: 1980: Las Vegas, Nev.). V. Symposium on Quality of Fruits and Vegetables of North America (1980: Las Vegas, Nev.). VI. American Chemical Society. VII. Series. SB360.Q34 635 81-14853 ISBN 0-8412-0662-7 AACR2 ACSMC8 170 1-240 1981

Copyright © 1981 American Chemical Society All Rights Reserved. The appearance of the code at the bottom of the first page of each article in this volume indicates the copyright owner's consent that reprographic copies of the article may be made for personal or internal use or for the personal or internal use of specific clients. This consent is given on the condition, however, that the copier pay the stated per copy fee through the Copyright Clearance Center, Inc. for copying beyond that permitted by Sections 107 or 108 of the U.S. Copyright Law. This consent does not extend to copying or transmission by any means—graphic or electronic—for any other purpose, such as for general distribution, for advertising or promotional purposes, for creating new collective work, for resale, or for information storage and retrieval systems. The citation of trade names and/or names of manufacturers in this publication is not to be construed as an endorsement or as approval by ACS of the commercial products or services referenced herein; nor should the mere reference herein to any drawing, specification, chemical process, or other data be regarded as a license or as a conveyance of any right or permission, tc the holder, reader, or any other person or corporation, to manufacture, reproduce, use, or sell any patented invention or copyrighted work that may in any way be related thereto. PRINTED IN THE UNITED STATES OF AMERICA

AMERICAN CHEMICAL

Society Library 1155 16th St. N. W.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; Washington, D. C. 20036 ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

ACS Symposium Series M . Joan Comstock, Series Editor

Advisory Board David L. Allara

James P. Lodge

Kenneth B. Bischoff

Marvin Margoshes

Donald D. Dollberg

Leon Petrakis

Robert E. Feeney

Theodore Provder

Jack Halpern

F. Sherwood Rowland

Brian M . Harney

Dennis Schuetzle

W. Jeffrey Howe

Davis L. Temple, Jr.

James D. Idol, Jr.

Gunter Zweig

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

FOREWORD The ACS SYMPOSIU

a medium for publishin format of the Series parallels that of the continuing ADVANCES IN CHEMISTRY SERIES except that in order to save time the papers are not typeset but are reproduced as they are submitted by the authors in camera-ready form. Papers are reviewed under the supervision of the Editors with the assistance of the Series Advisory Board and are selected to maintain the integrity of the symposia; however, verbatim reproductions of previously published papers are not accepted. Both reviews and reports of research are acceptable since symposia may embrace both types of presentation.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

PREFACE

A

lthough judgments of quality are largely subjective, certain distinctive L properties that define the degree of excellence can be identified. Scientists are curious about what specific constituents contribute to the predominant characteristics that determine quality. The ultimate goals of research efforts based on this interest are retention and maximization of foodstuff superiority and suppression of the development of undesirable constituents. This volume present vegetables growing in Nort processe protec them to bring them to our tables in the best quality possible. Such topics are important because the most nutritious food is absolutely useless if rejected. Furthermore, we must retain the enjoyment of our foods, or life will become dull indeed. Most chapters are papers presented at the Symposium on Quality of Fruits and Vegetables of North America held during the Second Chemical Congress of the North American Continent, which included the 180th National American Chemical Society meeting. The Congress was jointly sponsored by the American Chemical Society, The Chemical Institute of Canada, and the Sociedad Quimica de Mexico, and was held in Las Vegas, Nevada, August 24-29, 1980. Several chapters were added to make this volume more comprehensive. ROY TERANISHI

U.S. Department of Agriculture Western Regional Research Center Albany, CA 94710 HERIBERTO BARRERA-BENITEZ

Comision Nacional de Fruticultura, SARH Mexico City, Mexico March 30,1981

ix In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

Quality Factors in California Grapes A. DINSMOOR WEBB Department of Viticulture and Enology, University of California, Davis, C A 95616

D e f i n i t i o n s of Q u a l i t y Everyone knows what q u a l i t y i n a grape o r other commodity i s — o r do they? Q u a l i t y might be defined as those a t t r i b u t e s or c h a r a c t e r i s t i c s of the grape that make i t a t t r a c t i v e and pleasant to eat o r d e s i r a b l e f o r conversion t o wines which would be pleasant t o d r i n k . This d e f i n i t i o n seems p e r f e c t l y s t r a i g h t forward and l o g i c a l u n t i l one r e a l i z e s that those a t t r i b u t e s p l e a s i n g t o one person may be q u i t e unpleasant t o o t h e r s . Economists have defined q u a l i t y i n product o r commodity as any c h a r a c t e r i s t i c s that make i t appealing t o the purchaser. Here, a l s o , one runs i n t o the d i f f i c u l t y that c e r t a i n c h a r a c t e r i s t i c s may motivate one group o f people t o buy the o b j e c t , but may be completely u n a t t r a c t i v e t o others. I s t h e r e , then, some a b s t r a c t element of c h a r a c t e r i s t i c that can be u n i f o r m l y recogn i z e d as p r o v i d i n g r e l a t i v e l e v e l s of q u a l i t y t o a substance? Q u a l i t y i n grapes and wines might be defined as that p a r t i c u l a r balance o r harmony of other a t t r i b u t e s which makes the grape o r wine appealing and i n t e r e s t i n g t o an experienced t a s t e r . R e a l i z i n g that t h i s d e f i n i t i o n may s t i l l be u n s a t i s f a c t o r y i n that the man i n the s t r e e t may not agree w i t h the expert, we s h a l l n e v e r t h e l e s s consider C a l i f o r n i a grapes and the wines made from them from the p o i n t of view of t h i s understanding of q u a l i t y . R a i s i n Grapes The t o t a l crop of grapes produced i n C a l i f o r n i a v a r i e s from year t o year according t o the vagueries of c l i m a t e . F u r t h e r , the percentage of the r a i s i n grapes that are a c t u a l l y d r i e d i n t o r a i s i n s v a r i e s w i t h the world-wide market f o r r a i s i n s . I n years when t h i s market i s depressed, s i z a b l e q u a n t i t i e s of C a l i f o r n i a r a i s i n grape v a r i e t i e s w i l l be used f o r f r e s h consumption and f o r wine production. For example, i n 1979, f o r which p r e l i m i n a r y f i g u r e s are now a v a i l a b l e , (_1) of the t o t a l crop of 4,493,000

0097-6156/81/0170-0001 $05.00/0 © 1981 American Chemical Society In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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QUALITY OF SELECTED FRUITS AND VEGETABLES

tons, 51% or 2,300,000 tons c o n s i s t e d of r a i s i n grape v a r i e t i e s . Of t h i s q u a n t i t y of r a i s i n grapes, 60% or 1,374,000 tons was a c t u a l l y d r i e d to produce r a i s i n s ; the balance being d i v i d e d among 700,000 tons (30%) crushed, 60,000 tons (3%) canned, and 166,000 tons (7%) consumed as f r e s h f r u i t . While very s m a l l q u a n t i t i e s of Zante c u r r a n t s , Muscat grapes, and some new v a r i e t i e s are d r i e d to make r a i s i n s , the very great p r o p o r t i o n of the r a i s i n p r o d u c t i o n i s from the Thompson Seedless or S u l t a n i n a grape v a r i e t y . There i s l i t t l e q u e s t i o n that the best Thompson Seedless r a i s i n s are those produced from moderately cropped v i n e s grown on f e r t i l e , deep s o i l s (2). Fresh grapes of higher sugar c o n c e n t r a t i o n tend to produce r a i s i n s that are plumper, sweeter, and more meaty or chewy. Low sugar grapes, i n c o n t r a s t , produce r a i s i n s that are l e s s sweet, and which have much l a r g e r p r o p o r t i o n s of s k i n to f l e s h . As the sugar concent r a t i o n i n grapes v a r i e s i n v e r s e l y w i t h the crop l e v e l economics favors p r o d u c t i o n of r a i s i n q u a l i t y . The commercia the balance between p r o d u c t i o n and r a i s i n q u a l i t y . While there i s no q u e s t i o n that sugar i n the grape i s the most important f a c t o r i n r a i s i n q u a l i t y , the a c i d content and the content of other n o n - v o l a t i l e s o l i d s i n the grapes i s probably of secondary importance. A c i d i s p a r t i c u l a r l y important as an aspect of the f r e s h , f r u i t y f l a v o r . Low a c i d r a i s i n s , j u s t as low a c i d f r u i t , t a s t e f l a t and u n i n t e r e s t i n g i n comparison w i t h examples of s u f f i c i e n t a c i d i t y . F l a v o r compounds i n the grape are mainly produced by the dehydrating or d r y i n g process through a s e r i e s of f a i r l y complicated chemical r e a c t i o n s . The c o n t r i b u t i o n s of the v a r i o u s products of these r e a c t i o n s to the o v e r a l l grape f l a v o r i s c u r r e n t l y under i n v e s t i g a t i o n by S i n g l e t o n and h i s co-workers ( 3 ) . I t i s to be noted that f l a v o r s d i f f e r s i g n i f i c a n t l y between r a i s i n s produced by the sun-drying technique as compared w i t h the dehydrator techniques. F u r t h e r , use of chemicals to break down the bloom l a y e r on the s k i n s and thus f a c i l i t a t e the d r y i n g may have a secondary a f f e c t on the f l a v o r balance of the p a r t i c u l a r r a i s i n - t y p e . Table Grapes The term " t a b l e grape" i s used to d i s t i n g u i s h f r u i t that i s destined to be eaten f r e s h r a t h e r than to be d r i e d or made i n t o wine. Of course, any r i p e grape can be eaten f r e s h , but over the c e n t u r i e s there has been s e l e c t i o n of v a r i e t i e s that were seedless on the one hand and that were l a r g e r b e r r i e d , f i r m e r f l e s h e d and w i t h more a t t r a c t i v e c o l o r s on the other hand. S e l e c t i o n f o r a t t r a c t i v e c o l o r has been p a r a l l e l e d by s e l e c t i o n of l a r g e s i z e . We f i n d thus that q u a l i t y a t t r i b u t e s i n t a b l e grapes can be considered from two c a t e g o r i e s , the v i s u a l and the p a l a t e . V i s u a l f a c t o r s of obvious importance to q u a l i t y i n t a b l e f r u i t are s i z e , c o l o r , shape, and i n t a c t bloom on the b e r r i e s .

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

1.

WEBB

Quality Factors in California Grapes

3

Berry s i z e . There i s no question that l a r g e r s i z e i s a p o s i t i v e f a c t o r i n f a v o r i n g s a l e s of t a b l e grapes, p a r t i c u l a r l y i n the United States market. The v a l i d i t y of t h i s o b s e r v a t i o n i s supported by the i n c r e a s e i n consumption of Thompson Seedless grapes which have not only been g i r d l e d , but a l s o sprayed w i t h g i b b e r e l l i c a c i d to make the t r e a t e d b e r r y some four to f i v e times l a r g e r than the n a t u r a l berry (4). For a new t a b l e grape v a r i e t y to be s u c c e s s f u l i n the market, i t must be l a r g e i n s i z e . Berry c o l o r . Table grapes range i n c o l o r from pale greens through l i g h t y e l l o w s , golden c o l o r s , to the p i n k s , reds, and n e a r l y black. The mottled or s t r i p e d l i g h t red c o l o r on the p a l e , yellow-green background of the Flame Tokay v a r i e t y has undoubtedly been one of the f a c t o r s i n making i t a success i n the market. S i m i l a r l y , the s t r i k i n g , shiny b l a c k and the very l a r g e s i z e of the R i b i e r have undoubtedly been important f a c t o r s i n i t s s a l e s appeal. Table grape b e r r y shape of the wine or r a i s i n v a r i e t i e s . I t i s assumed that over the generations i n t e r e s t i n g mutants of b e r r y shape have been s e l e c t e d and preserved. Table grape b e r r i e s range from n e a r l y s p e r i c a l t o very elongated, c y l i n d r i c a l forms. Berry shape, as w e l l as c o l o r , i s c e r t a i n l y one of the f a c t o r s l e a d i n g to good s a l e s appeal i n these v a r i e t i e s . Berry s u r f a c e bloom. Of equal importance to the b e r r y shape and the c o l o r i s the a t t r a c t i v e n a t u r a l bloom on the s u r f a c e of the grape b e r r i e s . The bloom i s a t h i n l a y e r of w a x - l i k e m a t e r i a l c o a t i n g the outer s u r f a c e of the b e r r y and g i v i n g the impression that the berry has been l i g h t l y and u n i f o r m l y dusted or f r o s t e d (5). Great care i s r e q u i r e d d u r i n g harvest and packing of t a b l e grape v a r i e t i e s i n order that the bloom not be d i s t u r b e d . C l u s t e r s which have been handled roughly show e v i dence of t h i s i n areas where the bloom i s removed. Of p a r t i c u l a r importance i n the t a b l e grape v a r i e t i e s that are stored c o l d f o r prolonged periods before marketing i s the appearance and c o n d i t i o n s of the stem. Poor storage c o n d i t i o n s can l e a d to d r i e d out and brownish c o l o r e d stems which are much l e s s a t t r a c t i v e than the t u r g i d and green stems of the f r e s h fruit. Indeed, stem c o n d i t i o n and appearance i s one of the more important f a c t o r s i n the o v e r a l l appeal the c l u s t e r of grapes has to the purchaser (6). While v i s u a l f a c t o r s are probably o v e r r i d i n g i n the customer's d e c i s i o n concerning the purchase of t a b l e f r u i t , p a l a t e f a c t o r s cannot be completely discounted. Here we should consider seedlessness, t e x t u r e , and f l a v o r . Seedlessness, p a r t i c u l a r l y f o r the American market, has become a very d e s i r a b l e a t t r i b u t e i n t a b l e grapes. In c o n t r a s t to the p r a c t i c e i n Europe, where enormous q u a n t i t i e s of the s m a l l b e r r i e d , l a r g e seeded Chasselas dore are consumed, preference i n the United States i s d e f i n i t e l y f o r seedless v a r i e t i e s . Nearly a l l of the new v a r i e t i e s being introduced are without seeds.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

4

QUALITY OF SELECTED FRUITS AND VEGETABLES

In comparison w i t h the wine grape v a r i e t i e s , t a b l e grapes have a very f i r m and pulpy t e x t u r e . Most wine grape v a r i e t i e s e a s i l y l o s e t h e i r j u i c e when the s k i n i s broken. In c o n t r a s t , t a b l e grape v a r i e t i e s tend t o have a t e x t u r e more l i k e that of an apple or other f i r m f r u i t . This c h a r a c t e r i s t i c apparently i s appreciated by consumers of t a b l e grapes who r e f e r to the c r i s p n e s s and firmness of the t e x t u r e of the berry. The a t t r i b u t e of f l a v o r i s composed of both t a s t e and odor elements. Of the four b a s i c t a s t e s , only those of sweetness and sourness a r e of much s i g n i f i c a n c e . Some t a b l e grape v a r i e t i e s , p a r t i c u l a r l y when underripe, may have a h i n t of b i t t e r n e s s , but the s a l t y t a s t e i s almost never apparent. The v o l a t i l e aroma m a t e r i a l s that are perceived i n the n a s a l c a v i t y when the berry i s chewed and are thus thought of as part of the t a s t e , a r e very important to the p o s i t i v e appeal of many t a b l e grape v a r i e t i e s . In the Muscat-flavored s o r t s , w i t h t h e i r r e l a t i v e high concent r a t i o n of the terpene American v a r i e t i e s of th i s t i c aroma to the presence of the e s t e r , methyl a n t h r a n i l a t e together w i t h many other organic v o l a t i l e s . We s t i l l do not know what are the important compounds i n the c h a r a c t e r i s t i c aroma of the R o t u n d i f o l i a s p e c i e s . In comparison w i t h the wine v a r i e t i e s , t a b l e v a r i e t i e s u s u a l l y are harvested and consumed at lower concentrations of sugar, t y p i c a l l y around 150 grams per l i t e r r a t h e r than the 220 to 250 of wine v a r i e t i e s . A c i d c o n c e n t r a t i o n s , s i m i l a r l y , are u s u a l l y lower, and i n the range of 4 to 6 grams per l i t e r r a t h e r than the 8 t o 10 of wine v a r i e t i e s . O v e r a l l q u a l i t y i n the p a l a t e f a c t o r s of a t a b l e grape depends upon a harmonious balance of the elements making up the f l a v o r ( 8 ) . Of the t o t a l of 4,493,000 tons of grapes produced i n C a l i f o r n i a i n 1979, 413,000 tons or 9.2% were t a b l e grape v a r i e t i e s . Of t h i s 413,000 tons, 225,000 tons or 54.5% were a c t u a l l y consumed as f r e s h f r u i t , the balance being crushed to produce wine. I t should be noted that i t i s standard p r a c t i c e world-wide t o u t i l i z e scarred or blemished t a b l e grapes, which cannot be s o l d f o r consumption f r e s h , f o r the production of standard q u a l i t y wines or of d i s t i l l i n g m a t e r i a l . Wine Grapes For the 1979 season, of the t o t a l of 4,493,000 tons of grapes produced, 1,780,000 tons (40%) were c l a s s i f i e d as wine grape v a r i e t i e s . Of the wine grape v a r i e t i e s , 1,692,000 tons (95.1%) were crushed t o wine or d i s t i l l i n g m a t e r i a l . I t should be noted that the 4.9% not crushed according t o the r e p o r t s a c t u a l l y i n c l u d e s a l l of the f r u i t that was consumed f r e s h and used f o r a l l purposes on the vineyard p r o p e r t i e s . In great c o n t r a s t w i t h t a b l e grapes, wine grapes do not have t h e i r q u a l i t y i n f l u e n c e d by the presence of blemishes or scars

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

1.

WEBB

Quality Factors in California Grapes

5

produced by weather or rough handling. Q u a l i t y i n wine grapes i s determined by the composition of the m a t e r i a l i n s i d e the b e r r y . Freedom from mold, of course, i s a very important f a c t o r i n wine grape q u a l i t y j u s t as i t i s w i t h the other grape types. Wine grapes normally c o n t a i n 21 to 24% of fermentable s u g a r s — s i g n i f i c a n t l y higher than the concentrations u s u a l l y found i n the t a b l e grape v a r i e t i e s . A c i d l e v e l s , a l s o are s i g n i f i c a n t l y h i g h e r — normally ranging from 6 to 12 grams per l i t e r when expressed as t a r t a r i c a c i d (9). Sugar concentrations w i t h i n the mentioned ranges are important because the sugar, a f t e r conversion to a l c o h o l , determines whether the wine t a s t e s t h i n and watery or too a l c o h o l i c and hot. S i m i l a r l y , excessive c o n c e n t r a t i o n s o f a c i d i n the grape l e a d to wines that are too t a r t to be p a l a t a b l e , w h i l e i f the grape i s d e f i c i e n t i n a c i d , the wine w i l l be f l a t and u n i n t e r e s t i n g . Aroma compounds. Th much importance i n determinin s t u d i e s , employing gas chromatographic techniques f o r s e p a r a t i o n coupled w i t h mass spectrometric procedures f o r i d e n t i f i c a t i o n , have permited c h a r a c t e r i z a t i o n of some 300 v o l a t i l e organics as i n v o l v e d i n grape and wine aroma and bouquet (10, 11). While a number of these compounds are produced by the yeasts from nonv o l a t i l e s of the grape, a good many are n a t u r a l l y present i n the grape and come through the fermentation e i t h e r u n a l t e r e d or w i t h minor m o d i f i c a t i o n s . I t i s i n t e r e s t i n g that no s i n g l e compound seems to be completely r e s p o n s i b l e f o r the c h a r a c t e r i s t i c f l a v o r of any grape v a r i e t y . However, i t i s c l e a r t h a t methyl a n t h r a n i l a t e i s important i n the aroma of the l a b r u s c a species o f which the Concord i s the most important c u l t i v a r . The Muscat v a r i e t i e s of V i t i s v i n i f e r a owe t h e i r i n t e n s e c h a r a c t e r i s t i c aromas to the presence of a number of terpene a l c o h o l s , among which l i n a l o o l and g e r a n i o l are probably the most important. Cabernet Sauvignon, another V i t i s v i n i f e r a c u l t i v a r , has been reported to c o n t a i n s m a l l concentrations of methoxyisobutylp y r a z i n e , a compound w i t h a s t r o n g , green b e l l p e p p e r - l i k e aroma. Even w i t h these three c u l t i v a r s , many other v o l a t i l e organics are i n v o l v e d i n the complete grape aroma. Most of the other c u l t i v a r s that have been i n v e s t i g a t e d c o n t a i n l a r g e numbers o f v o l a t i l e s among which no s i n g l e one has been a s s o c i a t e d w i t h the c h a r a c t e r i s t i c c u l t i v a r aroma. P h e n o l i c compounds. The anthocyanins and tannins are p a r t i c u l a r l y important c o n s t i t u e n t s of wine grapes i n t h a t they provide the a t t r a c t i v e c o l o r to red wines and the d e s i r a b l e b i t terness and a s t r i n g e n c y a s s o c i a t e d w i t h the t a b l e wines. While the c o n c e n t r a t i o n s and types of anthocyanins present i n the v a r i o u s c u l t i v a r s and species d i f f e r , most red wine grapes cont a i n enough of these compounds i n the s k i n s so that s a t i s f a c t o r y c o l o r s are produced during the fermentation of the wine when the

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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a l c o h o l e x t r a c t s the pigment from the s k i n s (12)• Red v i n i f e r a v a r i e t i e s can u s u a l l y be d i s t i n g u i s h e d from the red v a r i e t i e s of the American species on the b a s i s that the former c o n t a i n only 3-monoglycoside pigments. As the gene f o r d y g l y c o s i d e pigment a t i o n appears to be dominant i n most cases, use of the American species i n breeding h y b r i d s can u s u a l l y be detected by t h i s c h a r a c t e r i s t i c . Tannins, i n c o n t r a s t w i t h the anthocyanins and pigments, are present i n the pulp, seeds, and stems as w e l l as i n the s k i n s . Tannin molecules of r e l a t i v e l y lower molecular weight are r e s p o n s i b l e f o r the b i t t e r t a s t e w h i l e those of higher molecular weight give r i s e to the t a c t i l e s e n s a t i o n of a s t r i n gency or puckeriness. A p p r o p r i a t e l e v e l s of these tannins i n the wine can be c o n t r o l l e d to a c e r t a i n degree by the conduct of the fermentation, but i t i s necessary that there be an adequate q u a n t i t y i n the grape i n order to have a balanced wine as a result. Wine grapes must c o n t a i yeast i n order to suppor Among these components are a number of v i t a m i n s and a number of m i n e r a l s . In a d d i t i o n to the major requirement f o r n i t r o g e n , phosphorous, and potassium, yeasts a l s o r e q u i r e a wide range of t r a c e elements. These must a l l be s u p p l i e d by the grape i n order that the fermentation w i l l be r a p i d and complete. F a c t o r s I n f l u e n c i n g Q u a l i t y i n Grapes To produce h i g h q u a l i t y grapes of the three types mentioned above r e q u i r e s c a r e f u l c o n t r o l of a number of f a c t o r s among which the v a r i e t y , the c l i m a t e , the s o i l , and vineyard management are probably of g r e a t e s t s i g n i f i c a n c e . There are complex i n t e r a c t i o n s among these f a c t o r s , and the p a r t i c u l a r assembly of f a c t o r s optimum f o r each of the b a s i c types of grape d i f f e r s . C u l t i v a r . I t i s obvious that the v a r i e t y or c u l t i v a r i s of fundamental importance. As mentioned e a r l i e r , the composition and s i z e of the grape v a r i e t i e s of the d i f f e r e n t types vary cons i d e r a b l y . This genetic i n h e r i t a n c e i s fundamental but v a r i a t i o n s i n other f a c t o r s can i n f l u e n c e the e x p r e s s i o n of the p o t e n t i a l q u a l i t y i n the p a r t i c u l a r c u l t i v a r . Thus, w h i l e a c u l t i v a r such as the Flame Tokay t a b l e grape does best i n the L o d i r e g i o n of C a l i f o r n i a , i t w i l l produce f r u i t r e c o g n i z a b l e as t a b l e grapes i n many of the other c l i m a t i c regions of C a l i f o r n i a . Climate. Of n e a r l y as great importance as the v a r i e t y or c u l t i v a r i n determining u l t i m a t e q u a l i t y of the f r u i t i s the c l i m a t e . Maximum, minimum, and average temperatures and the d a i l y p a t t e r n of heat accumulation are very important elements of the o v e r a l l c l i m a t e . The d i f f e r e n t grape c u l t i v a r s have somewhat d i f f e r e n t t o l e r a n c e s to temperatures and heat s t r e s s , but i n g e n e r a l , the grapevine i s a temperate r e g i o n p l a n t — s u f f e r i n g

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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s e v e r l y from very low w i n t e r temperatures and very warm, humid c o n d i t i o n s . R a i n f a l l and f o g and t h e i r d i s t r i b u t i o n through the season a r e a l s o of c o n s i d e r a b l e importance. C u l t i v a r s of the v i n i f e r a s p e c i e s need a l o n g , warm, d r y growing season. High humidity d u r i n g the growing season i s l i k e l y t o r e s u l t i n severe i n f e c t i o n s o f fungus d i s e a s e s which s e r i o u s l y impair the q u a l i t y of the f r u i t . Wind can be a problem i n that the young tender shoots of the v i n e i n the s p r i n g t i m e a r e e a s i l y broken. Of p a r t i c u l a r danger are l a t e s p r i n g f r o s t s which can k i l l t h e tender, young shoots of the v i n e and e a r l y w i n t e r f r e e z e s which can damage the wood of the canes and trunks before they have had time to winter-harden. S o i l . Much importance i s attached t o the s o i l of the v i n e yard by many w r i t e r s about grapes and wines. Here, as w i t h many t h i n g s i n v o l v i n g l i v i n g m a t e r i a l moderation seems to y i e l d the most s u c c e s s f u l r e s u l t s mote vigorous v i n e growt q u a l i t y . On the other extreme, very poor s o i l s which support only very meager l e a f growth a l s o lead t o uneconomically s m a l l crops, although they may be of high p o t e n t i a l as f a r as wine q u a l i t y i s concerned. Most important seems to be t h a t the s o i l be l o o s e and of a depth such that good drainage prevents the v i n e ' s r o o t s s t a y i n g wet. Husbandry of the v i n e y a r d . Vineyard management, comprising operations such as t r a i n i n g , pruning, pest c o n t r o l , and harv e s t i n g are o b v i o u s l y of great importance as f a r as f r u i t q u a l i t y i s concerned. The v a r i e t i e s of grapevines used i n comm e r c i a l vineyards world-wide have been so h i g h l y s e l e c t e d that they r e q u i r e c a r e f u l t r a i n i n g and pruning i n order t o produce optimum crops of h i g h q u a l i t y f r u i t . L e f t to themselves, they tend t o s e t more f r u i t than the v i n e can r i p e n , and to grow so v i g o r o u s l y that without pruning the v i n e y a r d soon becomes an impenetrable bush. The r e c e n t l y conceived ideas of i n t e r g r a t e d pest management are proving p a r t i c u l a r l y h e l p f u l i n c o n t r o l l i n g the many i n s e c t s and d i s e a s e s that a t t a c k the grapevine. Although the problems vary w i t h r e g i o n and from c u l t i v a r t o c u l t i v a r , some e f f o r t i s r e q u i r e d i n the management of p o t e n t i a l pests i n every s i t u a t i o n . The f i n a l step i n g e t t i n g high q u a l i t y f r u i t from the v i n e yard to the consumer s t a r t s w i t h h a r v e s t i n g . Here, o f course, the system and the degree of care v a r i e s w i t h the grape t y p e — t a b l e f r u i t r e q u i r i n g much more c a r e f u l hand l a b o r than does the h a r v e s t i n g of grapes f o r wine. Of prime importance, however, i n a l l cases i s that the harvest be conducted a t the optimum time. This means that the c o n c e n t r a t i o n s of sugar and a c i d must be c l o s e l y monitored toward the end of the r i p e n i n g p e r i o d and that the harvest must be conducted i n a r e l a t i v e l y short p e r i o d when these c o n s t i t u e n t s are present a t t h e i r optimum c o n c e n t r a t i o n s .

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Machine h a r v e s t i n g , w h i l e i n a p p l i c a b l e t o t a b l e grape v i n e y a r d s , i s e s p e c i a l l y s u i t e d t o r a i s i n and wine grape gathering. I n the case of the wine grape, there are the a d d i t i o n a l advantages that the o p e r a t i o n can be conducted during the c o o l n i g h t - t i m e p e r i o d r a t h e r than during the f u l l heat of the day, and that a f i e l d crusher can be coordinated w i t h the machine harvestor so that only the must i s taken i n t o the winery. With r a i s i n v a r i e t i e s t o be sun d r i e d i n the v i n e rows, machine h a r v e s t i n g can be adapted to place the f r e s h l y harvested f r u i t on a continuous paper t r a y layed i n the row f o l l o w i n g the machine. Summary Q u a l i t y i n grapes i s somewhat d i f f i c u l t t o d e s c r i b e . Somet h i n g of the economist's d e f i n i t i o n that q u a l i t y i s any charact e r i s t i c promoting s a l e seems present The idea that q u a l i t y i s an a b s t r a c t concept base tributes attractive to are three b a s i c types of grapes: r a i s i n grapes, t a b l e grapes, and wine grapes. Q u a l i t y i n r a i s i n grapes seems t o be c o r r e l a t e d w i t h optimum concentrations of sugar and a c i d i n the f r u i t a t the time o f harvest. V i s u a l f a c t o r s are very important i n q u a l i t y o f t a b l e grapes. S i z e , c o l o r , shape, and presence of undisturbed bloom a r e p a r t i c u l a r l y important. P a l a t e f a c t o r s such as seedl e s s n e s s and t e x t u r e as w e l l as a balance of f l a v o r a r e s i m i l a r l y important. With wine grapes, optimum concentrations of sugar, a c i d , p h e n o l i c s , aroma m a t e r i a l s , and growth f a c t o r s are very important. Factors i n f l u e n c i n g q u a l i t y i n grapes are v a r i e t y , c l i m a t e , s o i l , and vineyard management.

Abstract Of the 3,878,000 tons of grapes produced in California in 1978, 64% were converted to wine with the rest divided between raisin and fresh table use. Grape quality factors of importance for raisins are sugar, acid and extract concentrations; for table grapes visual factors such as size, color, shape, and bloom, and palate factors such as texture and flavoring are governing. For wine grapes, appearance is of little importance, but appropriate concentrations of sugar, acid, phenolics, minerals, vitamins, and aroma compounds are c r i t i c a l to high quality in the resultant wine. Grape composition at maturity is governed by the variety planted, the climate (including the temperature regime), the rainfall and fog, the wind, and air pollution. Soil and aspect of vineyard including soil composition, depth, drainage, and vineyard management, including the training system, the level of pruning, pest management, and the timing and method of harvest

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

1. WEBB Quality Factors in California Grapes

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are also of c r i t i c a l importance. Ultimate wine quality can be no better than potential quality inherent in the particular lot of grapes. Literature Cited 1.

2. 3. 4.

5. 6. 7. 8. 9.

10. 11. 12.

McGregor, R. Α., Lockhart, D. "California Grapes, Raisins, and Wine 1979. Production and Marketing" Federal-State Market News Service and California Crop and Livestock Reporting Service: Sacramento, CA, 1980. Winkler, A. J., Cook, J . Α., Kliewer, W. Μ., Lider, L. A. "General Viticulture"; University of California Press: Berkeley, 1974, p 639. Lin, Nen-Hua "Studies on Chemical Brown Pigments and Sensory Characteristics of Raisins Prepared by Different Methods" M.S. Thesis, Universit f California Davis CA 1980 Weaver, R. J., Sachs Fruit-Set and Berry Enlargement in Vitis vinifera L . " In Biochemistry and Physiology of Plant Growth Substances, Ed. Wightman and Setterfield, Runge Press Ltd.: Ottawa, Canada, 1968, p 957-974. Radler, F. Am. J. Enol. V i t i c . 1965, 16, 159-167. Nelson, Κ. E. "Harvesting and Handling California Table Grapes for Market"; University of California Division of Agricultural Sciences Pub. 4095, 1979. Cordonnier, R. C. R. Acad. Agric. 1955, 41, 399-403. Nelson, Κ. E. Am. J. Enol. V i t i c . 1973, 24, 31-40. Amerine, Μ. Α., Berg, H. W , Kunkee, R. E . , Ough, C. S., Singleton, V. L . , Webb, A. D. "The Technology of Winemaking, 4th Ed."; Avi Publishing Co. Inc.: Westport, Conn. 1980, Chap. 2. Webb, A. D. "Volatiles in Grapes and Wines"; Proc. Bienn. Int. CODATA Conf. 5th, 1976, Ed. Bertrand Dreyfus, Pergamon, Oxford, England, 1977, p 101-108. Schreier, P. "Flavor Composition of Wines: A Review"; CRC Press: Cleveland, Ohio, 1979. Ribéreau-Gayon, P. "The Chemistry of Red Wine Color" In Chemistry of Winemaking, Adv. in Chem. Series 137, A. D. Webb Ed., American Chemical Society, Washington, D.C., 1974, p 50.

RECEIVED

April 15, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

2 The Odor Quality of Labrusca Grapes TERRY E. ACREE New York State Agricultural Experiment Station, Cornell University, Geneva, NY 14456

Cultivars of the prevalent grapes plante Europe and Asia , vinifera grapes, of which there are several thousand named cultivars(1), also dominate the viticulture of the New World. In North America, however, two other species of Vitis (labrusca. Bailey and rotundifolia. Michaux) are grown in significant quantities(2). The severe climate and virulent disease in central and eastern North America made early cultivation of vinifera grapes largely unsuccessful, at least in the English Colonies. This stimulated the hybridization and cultivation of the more tolerant native grape species for many years. With the development of methods for disease control and the expansion of viticulture into climates more amenable to vinifera grapes, the percent of native species has decreased to less than five percent of the total North American grape production (3). Although dwarfed by the size of the vinifera grape crop, in excess of 4,000,000 tons, the production of labrusca grapes has increased in the last 30 years. This continued demand for labrusca grapes is due to their superior quality for the production of grape juice and j e l l y . It is the unique flavor of labrusca grapes, and in particular the cultivar Concord, that is responsible for their superiority. In fact, the flavor of labrusca grapes has become the standard of identity for grape juice and jelly in North America. TUS

QPQR

QF L A B R U S C A

CRAPES

The major f l a v o r d i f f e r e n c e s among grape products made w i t h d i f f e r e n t species of grapes are found i n the odor. I t i s easy to d i s t i n g u i s h the odors of grape j u i c e s made from vinifera, l a b r u s c a , and muscadine s p e c i e s . I n c o n t r a s t , the t a s t e of grapes, that i s t h e i r sweetness, sourness, and b i t t e r n e s s , i s f r e q u e n t l y manipulated by processors to the extent that any t a s t e d i f f e r e n c e among grapes of d i f f e r e n t species are o b l i t e r a t e d . The one word which has been used f o r c e n t u r i e s to describe the odor character o f n a t i v e grapes i s "foxy". I n f a c t e a r l y 0097-6156/ 81 /0170-0011 $05.00/ 0 © 1981 American Chemical Society In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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VEGETABLES

European v i s i t o r s to the New World named the n a t i v e labrusca grapes growing i n New England the Northern Fox Grape, and the n a t i v e grapes growing i n the South the Southern Fox Grape. The o r i g i n a l meaning of the word "foxy"* was e x p l i c i t l y s t a t e d i n 1722 by Robert Beverly when he described the smell of these grapes as resembling that of a f ox(â.) . This musky a n i m a l - l i k e aroma i s s t i l l considered an u n d e s i r a b l e a t t r i b u t e i n grapes, but " f o x y " must not be confused w i t h the powerful f r u i t y , f l o r a l , or candy odors e s s e n t i a l to the q u a l i t y of grape j u i c e and j e l l y . Even though these odors may not be appreciated i n most wine types, they are not the same as f o x i n e s s . The c u l t i v a r s of labruscana (Concord, Catawba, Delaware,etc.) were appreciated by early American grape breeders because of t h e i r general lack of f o x i n e s s . However, Niagara i s the one remaining commercial c u l t i v a r which has always been considered foxy. Therefore, f o x i n e s s should not be considered the dominant odor q u a l i t y of Labrusca grapes. In t h i labrusca grapes w i l l b During the sensory s t u d i e s of hundreds of d i f f e r e n t grape c u l t i v a r s conducted at the Experiment S t a t i o n i n Geneva, New York, p a n e l i s t s have, w i t h great r e g u l a r i t y , i d e n t i f i e d the presence of labrusca character i n the odor of labrusca grapes and o f t e n do the same w i t h h y b r i d crosses between γ. labruscana and other grape s p e c i e s . Furthermore, they can detect the presence of s p e c i f i c odor components, which i n v a r y i n g degrees, seem to make up the t o t a l sensory e f f e c t . Four d e s c r i p t o r s which are f r e q u e n t l y used by these p a n e l i s t s are " f o x y " , " f l o r a l " , "methyl a n t h r a n i l a t e - l i k e " , and "cotton candy". I t i s c e r t a i n l y unwise to assume that these odor components a r e , i n every case, r e l a t e d to s i n g l e chemical s p e c i e s , but they are probably less complicated i n t h e i r chemistry than the compound mix that produces the t o t a l perception of labrusca c h a r a c t e r . Such d e s c r i p t o r s are u s e f u l i n our attempts to s o r t out the small number of o d o r - a c t i v e compounds present i n natural products. However, they have l i t t l e meaning from one l a b o r a t o r y to the next. For example, the aroma described i n our work as "cotton candy" appears, f o r reasons which w i l l be explained l a t e r , to be due to the same compound r e s p o n s i b l e f o r the strawberry odor detected i n the l a b o r a t o r y of Rapp(5.) i n Germany. The confusion these non-chemical d e s c r i p t o r s c r e a t e , w i l l be minimized once we know the c a u s a t i v e agents f o r odor p e r c e p t i o n . Then we can use a chemical name to d e s c r i b e that p e r c e p t i o n . In the meantime, we must t o l e r a t e to some extent the use of these words i n our day-to-day r e s e a r c h . METHYL ANTHRANILATE Studies of the v o l a t i l e composition of grapes have, through the y e a r s , revealed the presence of so many o d o r - a c t i v e compounds that i t i s very u n l i k e l y that a s i n g l e compound i s r e s p o n s i b l e for more than a few percent of the t o t a l odor character of grapes of any k i n d ( & ) . Furthermore, among the hundreds of v o l a t i l e s

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Odor Quality of Labrusca Grapes

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present i n grapes (Figure 1 . ) , only a v e r y few probably have any odor a c t i v i t y . There must e x i s t a number of chemical compounds present i n grapes at p a r t i c u l a r concentrations that when taken together produce the c h a r a c t e r i s t i c odor q u a l i t y of a p a r t i c u l a r c u l t i v a r . A s s o c i a t e d w i t h each of these o d o r - a c t i v e chemicals i s a s p e c i f i c , though not n e c e s s a r i l y unique, odor q u a l i t y . One such compound i s methyl a n t h r a n i l a t e , the f i r s t compound ever a s s o c i a t e d w i t h odor character of a p a r t i c u l a r grape species (Z) · O r i g i n a l l y i d e n t i f i e d i n n e r o l i o i l (2.) » i t was used to produce s y n t h e t i c g r a p e - f l a v o r e d products before i t was observed i n grapes. I n 1923 Sale and Wilson (2.) analyzed the methyl a n t h r a n i l a t e content i n 55 c u l t i v a r s o f grapes, i n c l u d i n g both labrusca and v i n i f e r a c u l t i v a r s . They found methyl a n t h r a n i l a t e i n only 14 of these. I n 1976 using gas chromatography, we found methyl a n t h r a n i l a t e i n only 8 of 45 c u l t i v a r s ( 1 0 ) . C e r t a i n l y t h i s compound plays an important r o l e i n the f l a v o r of some o f the l a b r u s c a grapes bu labrusca character. Many wines w i t h a strong labrusca c h a r a c t e r have been found to have a methyl a n t h r a n i l a t e content w e l l below the apparent odor t h r e s h o l d (1Q.). Furthermore, the a d d i t i o n of t h i s compound to v i n i f e r a wines at very h i g h concentrations does not produce a l a b r u s c a aroma nor does i t produce a wine w i t h any f o x i n e s s . There a r e small amounts o f other a n t h r a n i l a t e e s t e r s , e t h y l , p r o p y l , s_££.-butyl and the analogous compound o_-aminoacetophenone i n l a b r u s c a grapes but there are no data e x p l a i n i n g t h e i r p r e c i s e c o n t r i b u t i o n , i f any, to the methyl a n t h r a n i l a t e - l i k e aroma. In the l a s t 60 y e a r s , perhaps too much emphasis has been placed on the methyl a n t h r a n i l a t e content of l a b r u s c a grapes. For example, measurements o f t h i s compound have been used to i n d i c a t e grape m a t u r i t y ( i l ) ; i t has been used as an i n d i c a t o r of the q u a l i t y of grape products(12), and as a means o f monitoring the performance of essence recovery equipment(11) · Furthermore, the amount of methyl a n t h r a n i l a t e combined w i t h the v o l a t i l e e s t e r content of grapes i s p r e s e n t l y being used to a i d the grape breeders i n t h e i r attempt to produce new c u l t i v a r s w i t h c e r t a i n odor c h a r a c t e r i s t i c s ( J A ) . One of the dangers of p l a c i n g too much importance on the presence of methyl a n t h r a n i l a t e i n grape products i s that such products may tend to smell more l i k e the simple i m i t a t i o n grape f l a v o r s r a t h e r than the n a t u r a l product. I t i s one of the goals of f l a v o r research to prevent such i r o n i e s from occurring un i n t e n t iona1ly· FOXINESS

So f a r our attempts to i s o l a t e a pure chemical component from l a b r u s c a o r muscadine grapes w i t h a c l e a r foxy odor have been u n s u c e s s f u l . There i s , however, one component, t r a n s - 2 - h e x e n - l - o l * apparently present i n a l l grape s p e c i e s , that has an odor very s i m i l a r to the foxy odor component o f Niagara grapes. P o s s i b l y , t h i s compound i s present i n f o x y - s m e l l i n g

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981. 70 MINUTES

30

SWEET C O N C O R D ODOR

40

1

1

Figure 1. Gas chromatograms from a Freon 113 extract of Concord grape juice concentrated 3,500 times (top) and the 3% ether-pentane fraction of a Florisil separation of the whole Freon 113 extract concentrated 13,000 times (bottom). The dots show regions where odor was detected. Conditions: 30 m χ 0.3 mm carbowax 20 M column, helium gasflowof 23 cm sec' programmed at6°Cmin .

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2.

ACREE

Odor Quality of Labrusca Grapes

15

grapes at a s u f f i c i e n t c o n c e n t r a t i o n to make a c o n t r i b u t i o n to t h e i r odor. I n f a c t , p r e l i m i n a r y examination showed that the c o n c e n t r a t i o n of t r a n s - 2 - h e x e n - l - o l i n an e x t r a c t of Niagara was 10 times higher than i n a s i m i l a r Concord e x t r a c t . The grape breeders of the past have v i r t u a l l y e l i m i n a t e d t h i s t r a i t from commercially important labrusca c u l t i v a r s . Among the muscadine grapes t h i s may not be the s i t u a t i o n , s i n c e s e v e r a l of the commercially important muscadine c u l t i v a r s seem to have a very foxy f l a v o r . THE FLORAL ODOR In an attempt to s i m p l i f y the complex mixture o f chemicals present i n e x t r a c t s o f labrusca grapes we have used 6% water d e a c t i v a t e d F l o r i s i l developed w i t h solvents of i n c r e a s i n g p o l a r i t y (15.)· Made by mixing d i e t h y l ether at 0, 1» 3, 10, 30, and 100% w i t h pentane, each solvent has approximately twice the p o l a r i t y of the previous one ( 1 6 ) With Concord grape j u i c e e x t r a c t s the f r a c t i o n w i t was the 3% f r a c t i o n whic c h a r a c t e r i s t i c . An a n a l y s i s of t h i s f r a c t i o n (15) showed the presence of damascenone [l-(2,6,6-trimethyl1,3-cyclohexadien-l-yl)-2-buten-l-one] a compound previously reported t o be present i n v i n i f e r a grapes(12.) as w e l l as other n a t u r a l products (IS.) · The p o s s i b l e importance of damascenone to the perception o f labrusca character can be i n f e r r e d from a comparison of the amounts of t h i s compound found i n e x t r a c t s o f labrusca and vinifera grape products (15.). I n a p r e l i m i n a r y a n a l y s i s o f products of 11 c u l t i v a r s , damascenone was highest i n e x t r a c t s o f Concord grape j u i c e , 5 ng/g ( f r e s h w e i g h t ) , 37 times higher than that found i n an e x t r a c t o f the v i n i f e r a c u l t i v a r , Pinot chardonnay. Because damascenone i s a ketone i t s v o l a t i l i t y i s reduced i n products c o n t a i n i n g s u l f u r d i o x i d e and thus i t s c o n t r i b u t i o n to the odor of labrusca wines w i l l be minimized ( 1 7 ) . However, i t s c o n t r i b u t i o n to the odor o f grape j u i c e and j e l l y may be s u b s t a n t i a l , e s p e c i a l l y s i n c e 5ng/g i s 700 times the odor t h r e s h o l d reported f o r t h i s compound i n water (IS.). I n c o n t r a s t , the methyl a n t h r a n i l a t e c o n c e n t r a t i o n u s u a l l y found i n Concord grapes i s only 50 times i t s t h r e s h o l d i n water(12.). Besides unknown substances yet to be i d e n t i f i e d , there are other good candidates f o r the f l o r a l odor of labrusca grapes. One such compound i s 2-phenylethyl a l c o h o l , which has an odor very reminiscent of labrusca c h a r a c t e r .

CQITQN CANDY For s e v e r a l years sensory panels ( i n our l a b o r a t o r y a t the Experiment S t a t i o n at Geneva, New York) have been e v a l u a t i n g the q u a l i t y of new h y b r i d grapes i n an e f f o r t to f i n d a replacement for the labrusca c u l t i v a r , I v e s . The p r o d u c t i v i t y of t h i s grape has been d e c l i n i n g f o r years because of i t s s e n s i t i v i t y to a i r pollution. One d e s c r i p t o r which i s f r e q u e n t l y a s s o c i a t e d w i t h the odor of Ives and i t s h y b r i d progeny i s "cotton candy".

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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QUALITY OF SELECTED FRUITS AND VEGETABLES

About two years ago a small quantity of a chromatographically pure compound w i t h a strong cotton candy odor was i s o l a t e d from e x t r a c t s of Ives grapes. Although there was only enough of t h i s compound to produce one GC-MS r u n , the spectrum was s i m i l a r t o , though not e x a c t l y l i k e , that reported r e c e n t l y by Rapp et al.(5.) f o r a compound i d e n t i f i e d i n Niagara grapes. This compound, called furaneol, (2,5-dimethyl-4-hydroxy-2H-furan-3-one) was described by Rapp as having a strong strawberry odor, whereas Hodge(20) who i s o l a t e d i t from a carbohydrate browning r e a c t i o n described i t as a burnt sugar aroma. As shown i n Figure 2 the spectrum we obtained from s y n t h e t i c furaneoK£,21,22.) superposable on that obtained f o r the cotton candy component i s o l a t e d from Ives grapes. C l e a r l y we are d e s c r i b i n g our sensory perceptions of the same compound using three d i f f e r e n t d e s c r i p t o r s , a situation which, although c o n f u s i n g , i s unavoidable at the moment. Because f u r a n e o l ca carbohydrates i t is b i o c h e m i c a l l y i n n a t u r a l products e i t h e r . I n f a c t there i s strong evidence that even damascenone i s sometimes produced non-enzymatically during the processing of natural products(2i»24.) · I t has been demonstrated, however, that f u r a n e o l i s produced e n z y m a t i c a l l y from f r u c t o s e i n homogenates of the f r u i t of a r c t i c bramble berry(25.) (Rubus a r c t i c u s L.) Furthermore, the methyl derivative of furaneol (2,5-dimethyl-4-methyoxy-2H-furan-3-one), a l s o found i n labrusca grapes(5.) and mango(26.)» increases r a p i d l y during the r i p e n i n g of a r c t i c bramble berry to become the major v o l a t i l e i n t h i s f r u i t . Furthermore, i t seems to be the o d o r - c h a r a c t e r i z i n g compound of the a r c t i c bramble b e r r y . We are p r e s e n t l y examining the importance of f u r a n e o l to the odor of other labrusca c u l t i v a r s besides Ives,where i t seems to cause the cotton candy aroma. As we l e a r n more about the o d o r - a c t i v e components of labrusca grapes we w i l l e l i m i n a t e such words as f l o r a l , foxy, and cotton candy from our sensory vocabulary and r e p l a c e them w i t h more rigorous descriptors such as damascenone, tcajls.-2-hexen-l-ol, and f u r a n e o l (Figure 3 ) . But the u l t i m a t e t e s t of our understanding of the f l a v o r chemistry of a n a t u r a l product would be the unambiguous synthesis of a mixture of chemicals w i t h an odor i n d i s t i n g u i s h a b l e from that of the n a t u r a l product. Although our present knowledge has yet to pass t h i s t e s t , we are g e t t i n g c l o s e r to an understanding of the chemical causes of labrusca c h a r a c t e r . w a s

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Odor Quality of Labrusca Grapes

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700% COTTON

80

C A N D Y SMELLING

60 40 20

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80

100

120

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Mass spectra obtained from the cotton candy-smelling compound iso­ lated from Ives grapes (top) and synthetic furaneol (bottom)

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

18

QUALITY OF SELECTED FRUITS AND VEGETABLES

COMPOUND NH,2

Ο

ODOR QUALITY METHYL ANTHRANILATE SYNTHETIC GRAPE

METHYL ANTHRANILATE

FOXY TRANS-2-HEXEN-l-OL

ANIMAL

FLORAL FRUITY DAMASCENONE Ο

OH

COTTON CANDY STRAWBERRY BURNT SUGAR

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Figure 3.

Some compounds isolated from labrusca grapes that may contribute to their odor quality

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

2. ACREE

Odor Quality of Labrusca Grapes

LITERATURE CITED 1. Galet, Pierre "Cepages et vignobles de France". Montpellier, 1956. 2. Hedrick, U. P. "The Grapes of New York". J . B. Lyon Albany, 1908. 3. Friedman, I . E. Proceedings New York State Hort. Soc. 1976, 121. 131. 4. Nelson, R. R. "Chemical and Sensory Analysis of Wines of Native American Grapes." Thesis, Cornell University, 1977. 5. Rapp, Α.; Knipser, W.; Engel, L. L . ; Ullemeyer, H . ; Heinmann, W. Vitis 1980, 19, 13. 6. Schreier, P. "CRC Critical Reviews in Food Science and Nutrition." 1979, Nov., 59. 7. Powers, F. B.; Chesnut, V. K . ; J.A.C.S. 1921, 43, 1741. 8. Gildemeister and Hoffman "Die Aetherischer Oele". 1910, 2 ed., III, 101. 9. Sale, J . W.; Wilson 10. Nelson, R. R.; Acree, T. E.; Lee, C. Y . ; Butts, R. M. J. Food S c i . 1977, 42, 57. 11. Robinson, W. B.; Shaulis,N. J.; Pederson, C. S. Fruit Prod. Ameriç. Food Manufacturer. 1949, 29, 36. 12. Military Specification. 1952, MIL-G-3791, 4. 13. Dimick, K. P.; Schultz, T. H . ; Makower, B. Food Technol. 1957, 11, 662. 14. Fuleki, T. R. Agric. Res. Inst. Ontario 1977-1978, p. 176. 15. Acree, T. E . ; Braell, P.; Butts, R. M. J. Agric. Food Chem. 1981, in press. 16. Snyder, L. R.; Kirkland, J . J . "Introduction to Liquid Chromatography". 1974, John Wiley, New York. 17. Schreier, P.; Drawert, F. Z. Lebens. Unters,-Forsch. 1974, 154, 273. 18. Ohloff, G. Perfumer Flavorists 1978, 3, 13. 19. Fazzalari, F. A. "Compilation of Odor and Taste Threshold Values Data". 1978, ASTM, Philadelphia, 99. 20. M i l l s , F . ; Hodge, J . E. Cardohyd, Res. 1976, 51, 9. 21. Snell, J . M.; McElvan, S. M. Org. Synth. 1943, II, 114. 22. Buchi, G.; Demole, E. J. Org, Chem, 1973, 38, 123. 23. Masuda, M.; Nishimura, K. J. Food S c i . 1980, 45, 396. 24. Schreier, P.; Drawert, F . ; Schmid, M. J. Sci. Food Agric. 1978, 29, 728. 25. Kallio, H. J. Food Sci. 1976, 41, 555. 26. Eriksson, C. E. "Progress in Flavour Research". 1979, Applied Science Publishers, London, 159. RECEIVED

April 15, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

19

3 Quality Characteristics of Muscadine Grape Products 1

L. F. FLORA and Τ. Ο. Μ. ΝΑΚΑYAMA Department of Food Science, University of Georgia Agricultural Experiment Station, Experiment, GA 30212

The muscadine grape vine was discovered in 1584 growing wild near the Scuppernon of North Carolina (1). grap species, Vitis munsoniana and Vitis rotundifolia. Vitis rotundifolia is the species commonly cultivated commercially in the Southeast. Work with this fruit was begun at the Georgia Experiment Station in 1909 and since that time a large mass of data has been accumulated (2). In most of the region where muscadine grapes are likely to succeed, the temperature does not often go lower than 10°F and it rarely goes to 0°F (3). Vitis rotundifolia differs so widely botanically from the other species of Vitis that some scientists place i t in a separate grouping. This distinctive grouping has become so well known in the southern states that to the grower there are two classes of grapes, muscadine or Scuppernong and the socalled bunch grapes (4). The muscadine group of grapes includes both the light or bronze varieties and the dark or black varieties. The most widely known variety of this group is the Scuppernong. The whole group is sometimes referred to as Scuppernong; however, the Scuppernong is only one of the white varieties belonging to the muscadine group (5). The fruit clusters of the muscadine group are small with the berries in many varieties tending to shell or fall from the cluster when ripe. The fruit is very characteristic having a thick leathery appearing skin with small russet dots in most varieties. The individual berries are large and round. The pulp is quite tough, but this toughness is not localized around the seed as with the labrusca. The fruit has a characteristic musky odor and in many varieties tends to ripen unevenly in the cluster. In contrast, the fruit cluster of the Vitis labrusca 1

Current address: American Home Foods, Milton, PA 17847. 0097-6156/81/0170-0021 $05.00/0 © 1981 American Chemical Society In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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QUALITY OF SELECTED FRUITS AND VEGETABLES

v a r i e t i e s a r e l a r g e r and u s u a l l y t a p e r i n g w i t h t h e b e r r i e s r i p e n i n g e v e n l y and s t r o n g l y h o l d i n g t o t h e c l u s t e r . The b e r r i e s a r e u s u a l l y c o v e r e d w i t h a waxy s e c r e t i o n known as bloom, which i s not present i n the r o t u n d i f o l i a grape. B o t h s p e c i e s o f g r a p e s , l a b r u s c a and r o t u n d i f o l i a , can be c l a s s i f i e d as s l i p s k i n s , t h a t i s t h e s k i n i s n o t a d h e r e n t t o the f l e s h (4). The m u c i l a g e n o u s p u l p and l e a t h e r y s k i n o f c r u s h e d m u s c a d i n e s a r e d i f f i c u l t t o h a n d l e i n w i n e making o p e r a t i o n s and t h e r e c o v e r y o f c l e a r j u i c e i s l o w . Sugar p e r c e n t a g e o f c u l t i v a t e d m u s c a d i n e s i s t o o low f o r w i n e m a k i n g w i t h o u t a m e l i o r a t i o n o f t h e must {6). In a 1934 s t u d y r e p o r t e d by A r m s t r o n g , P i c k e t t , and Murphy ( 5 J , s t u d y i n g 27 v a r i e t i e s o f m u s c a d i n e g r a p e s , t h e y f o u n d t h e number o f seeds p e r b e r r y r a n g e d f r o m 1.8 t o 3 . 4 , t h e p e r c e n t a g e o f s e e d was 2.1 t o 6 . 0 , t h e p e r c e n t a g e o f s k i n and p u l p r a n g e d f r o m 15.9 t j u i c e r a n g e d f r o m 64.6 t o f t h e e x p r e s s e d j u i c e f r o m 43 v a r i e t i e s o f g r a p e s t a k e n d u r i n g t h a t 1934 s e a s o n were t o t a l s o l i d s r a n g i n g f r o m 12.82% t o 2 1 . 3 2 % , pH r a n g i n g f r o m 3.42 t o 2 . 9 6 , t i t r a t a b l e a c i d i t i e s 54 t o 174 c c o f 0.1N NaOH p e r 100 cc o f j u i c e and t h e t a n n i n c o n t e n t 20 t o 417 mgs p e r l i t e r . F l o r a (_7) u p d a t e d t h e s e f i g u r e s i n a 1977a r e p o r t . Savage ( 4 J a l s o r e p o r t e d i n h i s 1941 r e p o r t t h a t p r a c t i c a l l y a l l o f t h e s u g a r s f o u n d i n t h e C o n c o r d g r a p e were r e d u c i n g s u g a r s w h i l e i n t h e m u s c a d i n e v a r i e t y such as t h e H u n t , S t u c k e y and D u l c e t , a l a r g e p r o p o r t i o n o f t h e s u g a r was sucrose. In g e n e r a l , t h e C o n c o r d j u i c e has c o n s i d e r a b l y more t i t r a t a b l e a c i d i t y t h a n t h e m u s c a d i n e j u i c e s . The m u s c a d i n e j u i c e s a l s o had c o n s i d e r a b l y l o w e r t a n n i n c o n t e n t s t h a n C o n c o r d juices. C a r r o l l , Hoover and N e s b i t t ( 8 ) , i n a 1971 s t u d y , a l s o r e c o g n i z e d t h a t the l e v e l of t o t a l s o l u b l e s o l i d s i n the mature f r u i t s o f V i t i s r o t u n d i f o l i a were l o w , r a n g i n g f r o m 10 t o 18%, w h i l e r i p e V i t i s v i n i f e r a and V i t i s l a b r u s c a b e r r i e s g e n e r a l l y r a n g e d between 19 t o 24% and 13 t o 2 1 % , r e s p e c t i v e l y . Glucose and f r u c t o s e a r e known t o be t h e p r i n c i p a l s u g a r s o f V i t i s v i n i f e r a w i t h s u c r o s e p r e s e n t i n o n l y t r a c e q u a n t i t i e s , whereas up t o 5.2% o f s u c r o s e was f o u n d i n t h e 12 c u l t i v a r s o f V i t i s r o t u n d i f o l i a s t u d i e d by C a r r o l l ( 8 ) . R e s e a r c h has shown t h a t r i p e n e s s i s i m p o r t a n t t o t h e q u a l i t y o f j u i c e s and w i n e s made f r o m m u s c a d i n e s . L a n i e r and M o r r i s (9) s e p a r a t e d m u s c a d i n e g r a p e s i n t o f i v e d e n s i t y g r a d e s u s i n g f o u r b r i n e s o l u t i o n s and r e p o r t e d t h a t t h e f l a v o r q u a l i t y o f j u i c e f r o m m u s c a d i n e s s o r t e d i n t o r i p e n e s s l e v e l s by t h e d e n s i t y f l o t a t i o n method i n c r e a s e d w i t h t h e r i p e n e s s o r s o l u b l e solids. C a r r o l l (TO) r e p o r t e d t h a t t h e q u a l i t y o r a c c e p t a b i l i t y o f w i n e made f r o m g r a p e s s e p a r a t e d i n t o r i p e n e s s l e v e l s by l i g h t s o r t i n g i n c r e a s e d t o a p o i n t and t h e n d r o p p e d o f f as t h e g r a p e s became o v e r r i p e .

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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FLORA AND NAKAYAMA

Quality of Muscadine Grape Products

23

C a r r o l l (Y\) r e p o r t e d i n 1975 t h a t m u s c a d i n e c u l t i v a r s l a c k e d s u f f i c i e n t s u g a r t o make b a l a n c e d and s t a b l e w i n e s . Lack o f s u f f i c i e n t s u g a r i s a common o c c u r r e n c e f o r g r a p e s g r o w i n g in the eastern United S t a t e s ; t h e r e f o r e , sugar or sucrose i s added t o a l l musts i n o r d e r t o i n c r e a s e t h e s u g a r c o n t e n t s t o 21° B r i x . A p p a r e n t l y t h e h u l l s o f muscadines c o n t a i n a p p r e c i a b l e amounts o f a c i d w h i c h a r e r e l e a s e d i n t o t h e f e r m e n t i n g w i n e . A f t e r f e r m e n t a t i o n on t h e s k i n and p r e s s i n g , most musts were h i g h enough i n a c i d i t y t o r e q u i r e a m e l i o r a t i o n w i t h 21° B r i x sugar syrup i n order t o reduce t h e t o t a l a c i d i t y of t h e f i n i s h e d wine t o a p a l a t a b l e l e v e l . One o f t h e u n i q u e a s p e c t s o f m u s c a d i n e g r a p e s i s t h e i r complement o f a n t h o c y a n i n p i g m e n t s . In a 1940 r e p o r t , Brown (12) s t a t e d t h a t t h e a n t h o c y a n i n o f t h e Hunt m u s c a d i n e g r a p e i s p r o b a b l y a 3 , 5 - d i g l u c o s i d e o f 3-0 m e t h y l d e l p h i n i d i n . This p i g m e n t was commonly r e f e r r e d t o as m u s c a d i n i n Ribereau-Gayon (13) showed t h a t t h e m u s c a d i n f i v e d i f f e r e n t anthocyanins m a l v i d i n , and p e o n i d i n . He a l s o d e m o n s t r a t e d t h a t t h e y o c c u r o n l y as d i g l u c o s i d e l i n k a g e s a t p o s i t i o n s 3 and 5 . Ballinger, Maness and N e s b i t t ( 1 4 ) c o n f i r m e d t h e s e f i n d i n g s w i t h seven c u l t i v a r s o f m u s c a d i n e s and t h r e e advanced s e l e c t i o n s f r o m t h e N o r t h C a r o l i n a Grape B r e e d i n g P r o g r a m . A l l c o n t a i n e d t h e same s u g a r , t h e 3 , 5 - d i g l u c o s i d e s and t h e f i v e a n t h o c y a n i n s as p r e v i o u s l y r e p o r t e d by R i b e r e a u - G a y o n ( 1 3 ) . F u r t h e r s t u d i e s by N e s b i t t , M a n e s s , B a l l i n g e r , and C a r r o l l (15) i n d i c a t e d t h e p o t e n t i a l c o l o r q u a l i t y o f m u s c a d i n e g r a p e s can be e f f e c t i v e l y d e t e r m i n e d w i t h o u t g o i n g t h r o u g h t h e w i n e making p r o c e s s . They d e m o n s t r a t e d t h a t good w i n e c o l o r was d i r e c t l y r e l a t e d t o t h e p r e s e n c e o f l a r g e amounts o f m a l v i d i n - 3 , 5 , d i g l u c o s i d e and t o a l e s s e r d e g r e e t o t h e petunidin-3,5-diglucoside. D e l p h i n i d i n - 3 , 5 - d i g l u c o s i d e was t h e most abundant f o r m o f a l l t h e d i f f e r e n t a n t h o c y a n i n s p r e s e n t ; h o w e v e r , t h e r e s e a r c h e r s f o u n d no a p p a r e n t c o r r e l a t i o n between the q u a n t i t y of the d e l p h i n i d i n - 3 , 5 - d i g l u c o s i d e present i n the g r a p e s and good w i n e c o l o r q u a l i t y . Based on t h e s e s t u d i e s t h e researchers concluded that increased methylation of i n d i v i d u a l anthocyanins r e s u l t e d i n g r e a t e r pigment s t a b i l i t y w i t h t h e m a l v i d i n - 3 , 5 - d i g l u c o s i d e h a v i n g t h e most d e s i r a b l e c o l o r e f f e c t a t a c o n c e n t r a t i o n o f e i g h t o r more m i l l i g r a m s p e r 100 grams o f f r e s h grapes. B a l l i n g e r ( 1 6 ) i n a s u b s e q u e n t 1974 s t u d y a l s o c o n f i r m e d these r e s u l t s with wines. He r e p o r t e d t h a t t h e g l y c o s i d e s o f m a l v i d i n a r e most s t a b l e i n w i n e s f o l l o w e d by p e o n i d i n , p e t u n i d i n , c y a n i d i n and d e l p h i n i d i n i n d e c r e a s i n g o r d e r o f stability. F l o r a ( 1 7 ) i n 1978 r e p o r t e d a r a n g e i n a n t h o c y a n i n c o n c e n t r a t i o n s f r o m 40 t o 403 mgs p e r 100 g o f f r u i t i n 11 c u l t i v a r s of muscadines w i t h wide v a r i a t i o n s i n t h e r e l a t i v e contents of i n d i v i d u a l anthocyanins. D e l p h i n i d i n was u s u a l l y

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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t h e most p r e v a l e n t a n t h o c y a n i n i n t h e p i g m e n t c o m p l e x f o l l o w e d by c y a n i d i n o r p e t u n i d i n , p e o n i d i n and m a l v i d i n . Cultivars w i t h r e l a t i v e l y h i g h m a l v i d i n and t o t a l a n t h o c y a n i n c o n t e n t s y i e l d e d j u i c e s and j e l l i e s w i t h t h e h i g h e s t q u a l i t y and most stable colors. Harvest date i n f l u e n c e d r e l a t i v e percentages of p e o n i d i n , m a l v i d i n and d e l p h i n i d i n . M a t u r i t y l e v e l i n f l u e n c e d t h e r e l a t i v e p e r c e n t a g e o f m a l v i d i n and c o n c e n t r a t i o n s o f a l l anthocyanins. One o f t h e more s e r i o u s p r o b l e m s e n c o u n t e r e d w i t h m u s c a d i n e j u i c e s and w i n e s i s i n t h e p r e s e r v a t i o n o f t h e d e s i r a b l e appearance or c o l o r of the p r o d u c t . P r e v e n t i o n o f undue discoloration is quite d i f f i c u l t . Few s t u d i e s have been c o n d u c t e d t o e x p l a i n t h e mechanisms o f b r o w n i n g and t o d e s i g n a p p r o p r i a t e methods f o r t h e e l i m i n a t i o n o r t h e p a r t i a l p r e v e n t i o n o f t h i s phenomenon. The t e n d e n c y o f t h e anthocyanin-3,5-diglucoside which t i th muscadin g r a p e s t o brown more s e v e r e l e s t a b l i s h e d by R o b i n s o (J8) Q ) Thoug o x i d a t i o n appears to p l a y a p a r t i n the browning of the muscadine pigments, pigment p o l y m e r i z a t i o n or c o n d e n s a t i o n a l s o seems t o be i n v o l v e d . Though Woodroof ( 2 0 ) f o u n d t h a t a d d i n g a s c o r b i c a c i d t o c o n t a i n e r s o f p a s t e u r i z e d m u s c a d i n e g r a p e j u i c e w h i c h had been opened a i d e d i n r e d u c i n g d a r k e n i n g and f l a v o r l o s s due t o o x i d a t i o n , F l o r a ( 2 1 ) f o u n d t h a t a s c o r b i c a c i d added t o c o n t a i n e r s of red muscadine grape j u i c e a c c e l e r a t e d the f a d i n g and b r o w n i n g o f t h e j u i c e i n s t o r a g e . R e f r i g e r a t i o n was t h e s i n g l e most e f f e c t i v e t o o l i n m a i n t a i n i n g c o l o r and f l a v o r o f juice. S u l f u r d i o x i d e improved r e t e n t i o n of j u i c e c o l o r . In a 1 9 7 6 s t u d y by F l o r a {22) r e p o r t i n g t h e t i m e - t e m p e r a t u r e i n f l u e n c e on m u s c a d i n e g r a p e j u i c e q u a l i t y , he f o u n d t h a t j u i c e c o l o r became u n a c c e p t a b l e as t h e b r o w n i n g i n d e x , t h e r a t i o o f a b s o r b a n c e a t 5 2 0 nm o v e r t h e r a t i o o f a b s o r b a n c e a t 4 2 0 nm, d r o p p e d b e l o w 3 . 4 w i t h t h e t r i s t i m u l u s A v a l u e d r o p p e d b e l o w + 2 2 . The c o l o r damage f r o m h e a t i n g t h e r e d muscadine j u i c e s progressed i n a r o u g h l y l o g a r i t h m i c f a s h i o n f r o m 4 6 ° C t o 1 2 1 ° C w i t h a Q-JQ r a t e change f a c t o r o f a p p r o x i m a t e l y 1 . 4 . T e m p e r a t u r e r e s i d e n c e and t o t a l h e a t i n p u t had t h e g r e a t e s t e f f e c t i n c o l o r c h a n g e s . Aroma c h a n g e s preceded u n a c c e p t a b l e c o l o r changes i n t h e heated j u i c e s . M u s c a d i n e s o f t h e r o t u n d i f o l i a v a r i e t y have been used t o f u r n i s h t h e c h a r a c t e r i s t i c aroma t o b l e n d s p r e d o m i n a t i n g i n t h e neutral flavored v i n i f e r a s . In f a c t , a h y b r i d c o n t a i n i n g t h e d e s i r a b l e aroma c h a r a c t e r i s t i c and d i s e a s e r e s i s t a n c e o f t h e r o t u n d i f o l i a w i t h t h e v i g o r and c r o p p r o d u c i n g t r a i t s o f some o f t h e v i n i f e r a v a r i e t i e s w o u l d be h i g h l y d e s i r a b l e . The r o s e - l i k e aroma o f β - p h e n y l e t h a n o l i s an i m p o r t a n t c o n s t i t u e n t of t h e V i t i s r o t u n d i f o l i a aroma. B i t t e r phenolics present in V i t i s l a b r u s c a - V i t i s v i n i f e r a hybrids are e s p e c i a l l y i m p o r t a n t i n h y b r i d s w i t h V i t i s c i n e r e a and V i t i s c o r t f o l i a b u t

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

3.

FLORA AND NAKAYAMA

Quality of Muscadine Grape Products

are n o t p r e s e n t i n V i t i s r o t u n d i f o l i a . Olmo ( 6 ) , r e p o r t i n g i n 1 9 7 1 on h y b r i d t r i a l s w i t h v i t i s v i n i f e r a and Y i t i s r o t u n d i f o l i a , f o u n d t h a t t h e a r o m a t i c components o f t h e V i t i s r o t u n d i f o l i a i n c o n t r a s t with those of the V i t i s labrusca are seldom r e c o v e r e d i n h y b r i d s w i t h V i t i s v i n i f e r a o r a r e p r e s e n t i n s u c h d i l u t e d f o r m as t o be u n r e c o g n i z a b l e . In a 1 9 5 6 r e p o r t , Kepner and Webb ( 2 3 ) r e p o r t e d t h a t t h e presence of β - p h e n y l e t h a n o l w i t h i t s r o s e - l i k e odor undoubtedly i s i m p o r t a n t i n t h e aroma o f t h e r o t u n d i f o l i a g r a p e . The a u t h o r s i d e n t i f i e d 1 8 components p r e s e n t i n m u s c a d i n e g r a p e f l a v o r i n c l u d i n g ethyl a l c o h o l , butyl a l c o h o l , hexyl a l c o h o l , an a c e t a t e e s t e r , a l a u r a t e e s t e r , m e t h y l a l c o h o l , h e x a n a l , 2 - h e x e n a l , isoamyl a l c o h o l , acetaldehyde, isobutyraldehyde, b i a c e t y l , ethyl acetate, a caproate e s t e r , a caprylate e s t e r , a c a p r a t e e s t e r , a l a u r a t e e s t e r , and t h e y a l s o i d e n t i f i e d as probably being present methyl e t h y l ketone, i n a d d i t i o n t o t h e β-phenylethanol. Of p a r t i c u l a p r e l i m i n a r y t e s t from t h i n i t r o g e n - , h a l o g e n - , and s u l f u r - c o n t a i n i n g compounds i n t h e r o t u n d i f o l i a v o l a t i l e essence. The l a c k o f t h e n i t r o g e n - c o n t a i n i n g compound o f v o l a t i l e e s t e r s i n r o t u n d i f o l i a g r a p e s may be a means o f d i f f e r e n t i a t i n g i t f r o m l a b r u s c a grapes which possess n i t r o g e n - c o n t a i n i n g a n t h r a n i l i c e s t e r s . The more r e c e n t s t u d i e s , F l o r a e t a l . ( 2 4 J , i d e n t i f i e d s e v e r a l c o n s t i t u e n t s o f muscadine grape essence u s i n g g a s - l i q u i d c h r o m a t o g r a p h y i n c o n j u n c t i o n w i t h mass s p e c t r o m e t r y and i n f r a r e d s p e c t r o m e t r y . Components i d e n t i f i e d i n c l u d e d methanol, ethanol, n-butanol, 2 - m e t h y l - l - b u t a n o l , n-hexanal, t r a n s - 2 - h e x e n e - l - a l , β-phenylethanol, acetaldehyde, ethyl acetate, ethyl propionate, propyl acetate, butyl acetate, ethyl c a p r a t e , b e n z y l a c e t a t e , t o l u e n e , m - x y l e n e , and d - l i m o n e n e . The a u t h o r s a s s e s s e d t h e r e l a t i v e i m p o r t a n c e o f t h e s e components u s i n g gas c h r o m a t o g r a p h i c e f f l u e n t s n i f f i n g . β - p h e n y l e t h a n o l seems t o be t h e component most l i k e t h e m u s c a d i n e f l a v o r w i t h b e n z y l a c e t a t e and one o r two unknowns a l s o c o n t r i b u t i n g a g r a p e y f l a v o r o r aroma. In a s u b s e q u e n t s t u d y by S i s t r u n k ( 2 _ 5 ) , i t was f o u n d t h a t t h e c o n c e n t r a t i o n s o f some o f t h e v o l a t i l e s w h i c h c h a r a c t e r i z e d t h e good m u s c a d i n e f l a v o r have a c u r v i l i n e a r r e l a t i o n s h i p w i t h acceptability. The most a c c e p t a b l e c u l t i v a r s o f m u s c a d i n e g r a p e j u i c e were t h o s e w h i c h c o n t a i n e d i n t e r m e d i a t e l e v e l s o f important v o l a t i l e components. In g e n e r a l , l o w and medium b o i l i n g v o l a t i l e s were d e c r e a s e d b y h o t - p r e s s i n g o f m u s c a d i n e grape j u i c e . F l a v o r q u a l i t y o f h o t - p r e s s e d j u i c e seemed t o be d e t e r m i n e d more by n o n v o l a t i l e components t h a n by v o l a t i l e f l a v o r components. S t o r a g e t e m p e r a t u r e had some e f f e c t upon v o l a t i l e s c o n c e n t r a t i o n i n processed muscadine grape j u i c e . A few v o l a t i l e s i n c l u d i n g e t h y l a c e t a t e , e t h y l p r o p i o n a t e and b u t y l a c e t a t e were s i g n i f i c a n t l y l o w e r i n j u i c e s t o r e d a t 2 1 ° C as opposed t o j u i c e s t o r e d a t a r e f r i g e r a t e d t e m p e r a t u r e o f

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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QUALITY OF SELECTED FRUITS AND VEGETABLES

4°C. The o v e r a l l a c c e p t a b i l i t y o f j u i c e s t o r e d a t 21°C was s i g n i f i c a n t l y lower than the j u i c e s t o r e d at 4°C. Volatiles c o n c e n t r a t i o n s s i g n i f i c a n t l y d e c r e a s e d d u r i n g 12 weeks o f s t o r a g e , p r o b a b l y due t o o x i d a t i o n and g e n e r a l d e g r a d a t i o n . The most p r o n o u n c e d d e c r e a s e s o c c u r r e d e a r l y i n t h e s t o r a g e period. U s i n g o b j e c t i v e and s u b j e c t i v e t e c h n i q u e s , S i s t r u n k (25) d e t e r m i n e d t h a t e t h y l a c e t a t e , b e n z y l a c e t a t e and β-phenylethanol are probably of primary importance to the t y p i c a l f l a v o r of muscadines. E t h y l a c e t a t e c o m p r i s e d 25% 91% o f t h e t o t a l v o l a t i l e c o n c e n t r a t i o n s o f j u i c e s and a t optimum l e v e l s was r e s p o n s i b l e f o r f r u i t y aroma and f l a v o r . B e n z y l a c e t a t e and β - p h e n y l e t h a n o l a r e t h e components w h i c h a r e most a s s o c i a t e d w i t h t h e m u s c a d i n e g r a p e aroma and f l a v o r . Unknown components d e t e c t e d i n e s s e n c e e x t r a c t s f r o m m u s c a d i n e g r a p e j u i c e by e f f l u e n t s n i f f i n g a l s o seemed t o be o f primary importance to th are c o n t i n u i n g to i d e n t i f

Literature Cited 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17.

Reimer, F. C. 1909. North Carolina Exp. Sta. Bull. 201. p. 21. Stuckey, H. P. 1919. Ga. Expt. Sta. Bull. No. 113. p. 62-74. Dearing, C. 1947. Farmer's Bull. No. 1785, U.S. Dept. of Agriculture pp. 1-29. Savage E. F. 1941. Ga. Expt. Sta. Bull. 217. p. 36 Armstrong, W. D., Pickett, Τ. Α., and Murphy, Μ. Μ., Jr. 1934. Ga. Expt. Sta. Bull. 185. p. 1-35. Olmo, H. 1971. Am. J . Enol. Viti. 22:87-91. Flora, L. F. 1977a. J . Food Sci. 42:935-938, 952. Carroll, D. E., Hoover, M. W., and Nesbitt, W. B. 1971. J . Am. Soc. Hort. Sci. 96:737-740. Lanier, M. R. and Morris, J . R. 1979. J . Am. Soc. Hort. Sci. 104:249-252. Carroll, D. E. Ballinger, W. E., McClure, W. F., and Nesbitt, W. B. 1978. Am. J. Enol. V i t i c . 29(3):169-171. Carroll, D. E., Nesbitt, W. B., and Hoover, M. W. 1975. J . Food Sci. 40:919-920. Brown, W. L. 1940. J . Am. Chem. Soc. 62:2808-2810. Ribereau-Gayon, P. 1964. An. Physiol. Veg. 6(3):211. Ballinger, W. E., Maness, E. P., Nesbitt, W. B., and Carroll, D. E. 1973. J. Food Sci. 38:909-190. Nesbitt, W. B., Maness,E. P., Ballinger, W. E., and Carroll, D. E. 1974. Am. J . Enol. V i t i c . 25:30-32. Ballinger, W. E . , Maness, E. P., Nesbitt, W. B., Makus, D. J., and Carroll, D. E. 1974. J . Am. Soc. Hort. Sci. 99:338-341. Flora, L. F. 1978. J . Food Sci. 43:1819-1821.

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Robinson, W. B., Weirs, L. D., Bertino, J . J., and Mattick, L. R. 1966. Am. J . Enol. V i t i c . 27:178-184. 19. Van Buren, J . P., Bertino, J . J., and Robinson, W. B. 1968. Am. J . Enol. V i t i c . 19:147-154. 20. Woodroof, J . G., Cecil, S. R., and DuPree, W. E. 1956. Ga. Agric. Exp. Sta. Bull. N.S. 17, 35 pp. 21. Flora, L. F. 1977b. Am. J. Enol. Vitic. 28(3):171-175. 22. Flora, L. F. 1976. J . Food Sci. 41:1312-1315. 23. Kepner, R. E. and Webb, A. D. 1956. Am. J. Enol. V i t i c . 7:8-18. 24. Flora, L. F . , Coleman, R. L . , and Bryan, W. L. 1977. Ann. Meeting Inst. Food Technol. p. 108 25. Sistrunk, C. P. 1979. M.S. Thesis, U. of Ga. 92 p. RECEIVED

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In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

4 Raisin and Dried Fig Volatile Components: Possible Insect Attractants RON G. BUTTERY, RICHARD M. SEIFERT and LOUISA C. LING Western Regional Research Laboratory, SEA, USDA, Berkeley CA 94710 EDWIN I. SODERSTROM and ALBERT P. YERINGTON StoredProductsInsectsResearchLaboratory,SEA,USDA,Fresno,CA93727

The vacuum steam volatile oils of both raisins and dried figs have been analyzed by capillar 38 components were identifie 34 components in the volatile oil of dried figs. Major volatile components in both raisins and dried figs included fatty acid degradation products such as nonanoic and octanoic acids, (E)-2decenal, (E)-2-octenal and nonanal. Benzaldehyde was an additional major component of dried figs. The most unusual components were 2-hexyl-3-methyl-maleic anhydride and l-octen-3one in the raisin volatile oil. Certain insects such as the Indian meal moth (Plodia interpunctella) and saw tooth grain beetle (Oryzaephilus surinamensis) infest dried fruits. It seems reasonable that these insects are attracted to the dried fruit, at least to some extent, by the characteristic odor of the dried fruit. The present study was begun to identify the volatile (odor) components of raisins and dried figs in order to be in a position to test these compounds for attraction. The volatiles of raisins had been previously studied by Ramshaw and Hardy (1). The volatiles of fresh figs had been previously studied by Jennings (2). EXPERIMENTAL Materials. Good quality dried raisins (dried Thompson seedless grapes), dried figs and fresh figs (Calimyrna variety) were obtained from processors in the Fresno, California area and from local markets for comparison. Authentic chemical compounds for comparison were obtained from reliable commercial sources or synthesized by known methods. Isolation of Volatile Oils. Whole raisins (1500g) were placed in a 12 L flask together with 6 L of odor free water. A Likens-Nickerson steam d i s t i l l a tion continuous extraction head was attached to the flask. This chapter not subject to U.S. copyright. Published 1981 American Chemical Society In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

30

QUALITY OF

S E L E C T E D FRUITS A N D

VEGETABLES

P u r i f i e d hexane (100 mL) was p l a c e d i n a 250 mL f l a s k a t t a c h e d t o the s o l v e n t arm of the head. The i s o l a t i o n was c a r r i e d out under reduced pressure (100 mm Hg) f o r 3 hours w i t h the r a i s i n s a t ca. 50°C. Cooling of the head condenser was c a r r i e d out w i t h an ethanol-water mixture a t 0°C. A dry i c e cooled r e f l u x condenser was placed on the o u t l e t of the head. A f t e r the i s o l a ­ t i o n the hexane e x t r a c t was d r i e d by f r e e z i n g out any drops of water and f i l t e r e d . The hexane s o l u t i o n was then concentrated u s i n g low hold up d i s t i l l a t i o n columns t o g i v e the r a i s i n volatile oil. The v o l a t i l e o i l from whole d r i e d f i g s was i s o l a t e d u s i n g e s s e n t i a l l y the same procedure as f o r the r a i s i n s except that the weight of d r i e d f i g s was 1 Kg. The v o l a t i l e o i l from whole f r e s h f i g s was i s o l a t e d a l s o u s i n g e s s e n t i a l l y the same procedure as f o r r a i s i n s except u s i n g 3 Kg of f r e s h f i g s . V o l a t i l e O i l from D r i e d f i g s (1 Kg) were added t o water (1.5 L) i n a 5 L beaker. Bakers yeast (0.25 g) was then added and the mixture s t i r r e d b r i e f l y . The beaker was covered w i t h c h e e s e c l o t h and the mixture allowed t o ferment a t room temperature (25°C) f o r 3 days. The mixture together w i t h 4 L of odor f r e e water was t r e a t e d u s i n g a Likens-Nickerson head vacuum steam d i s t i l l a t i o n c o n t i n u a l e x t r a c t i o n procedure as d e s c r i b e d above f o r r a i s i n s . Other batches of fermented f i g prepared as above were e x t r a c t e d d i r e c t l y w i t h f r e s h l y d i s t i l l e d d i e t h y l ether (3 χ 500 mL). The ether was then concentrated t o g i v e the v o l a t i l e o i l as f o r the hexane e x t r a c t s . D i r e c t Vapor Analyses. Samples of f r e s h f i g or rehydrated dry f i g (100 g) were enclosed i n a wide mouth Erlenmyer f l a s k (250 mL) and the f l a s k covered w i t h aluminum f o i l . Samples of vapor (10 mL) from above the f i g s was drawn up i n t o a c l e a n dry g l a s s s y r i n g e and i n j e c t e d d i r e c t l y i n t o the c a p i l l a r y GLC column ( c f . _3). T h i s procedure was used f o r both the c a p i l l a r y GLC-mass spectrometry analyses and the q u a n t i t a t i v e a n a l y s e s . Q u a n t i t a t i v e analyses were made by comparison of peak areas w i t h those from vapor samples above known c o n c e n t r a t i o n s of the compounds i n water solution. C a p i l l a r y GLC-Mass S p e c t r a l (GLC-MS) A n a l y s i s . T h i s was c a r r i e d out u s i n g a 150 m long by 0.64 mm i . d . Pyrex g l a s s c a p i l l a r y column coated w i t h Carbowax 20-M. The column was h e l d a t 50°C f o r 30 minutes a f t e r i n j e c t i o n and then temperature programmed a t 1°/minute t o 170°C and h e l d at t h i s

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

4.

BUTTERY ET AL.

Raisin and Dried Fig Volatile Components

31

upper l i m i t . A s i n g l e stage L l e w e l l y n - L i t t l e J o h n s i l i c o n e rubber membrane separator was used t o couple the end of the c a p i l l a r y column t o the mass spectrometer (a m o d i f i e d Consolidated 21-620 c y c l o i d a l t y p e ) . E l e c t r o n i o n i z a t i o n was 70 eV. RESULTS AND DISCUSSION Raisin Volatiles. Steam d i s t i l l a t i o n continuous e x t r a c t i o n of the r a i s i n s under reduced pressure gave a v o l a t i l e r a i s i n o i l which amounted to 5-10 ppm of the r a i s i n s . The o i l was analyzed by c a p i l l a r y GLC-mass spectrometry (GLC-MS). The a n a l y s i s was repeated w i t h v o l a t i l e o i l s from s e v e r a l d i f f e r e n t samples of r a i s i n s . F i g u r e I shows a GLC a n a l y s i s of t y p i c a l o i l . The r e s u l t s are l i s t e d i n Table I . Peak numbers corresponding t o the peaks i n F i g u r e I are shown i n the f i r s t colum name. Some i d e a of th components i n a t y p i c a l o i l ( c a l c u l a t e d from peak areas) i s a l s o l i s t e d i n Table I . The major compounds i n the r a i s i n v o l a t i l e o i l i n c l u d e the a l i p h a t i c a c i d s o c t a n o i c , nonanoic, hexanoic, heptanoic, and decanoic a c i d s as w e l l as 2-hexyl-3-methylmaleic anhydride ( p r e v i o u s l y i d e n t i f i e d by some of the authors, , nonanal, phenylacetaldehyde and 2 - p e n t y l f u r a n . The most unusual component i s 2-hexyl-3-methylmaleic anhydride. Anhydrides are u s u a l l y hydrolyzed by water and are not l i k e l y t o occur i n foods because most foods have h i g h c o n c e n t r a t i o n s of water. C o n d i t i o n s i n d r i e d foods are a p p a r e n t l y , however, s u i t a b l e f o r the s t a b i l i t y and p o s s i b l y the formation of anhydrides. I t i s s u r p r i s i n g that t h i s anhydride s u r v i v e s the vacuum steam d i s t i l l a t i o n i s o l a t i o n procedure although the r e l a t i v e l y low temperature (ca. 50°C) and l i k e l y r a p i d t r a n s f e r t o the hexane s o l v e n t are probably favorable. Another unusual component i s the potent odorant l - o c t e n - 3 one which has been r e p o r t e d t o have a mushroom-metallic aroma and has been found i n cooked mushroom (5) and a r t i c h o k e (6). The major components, except f o r phenylacetaldehyde and p o s s i b l y 2-hexyl-3-methylmaleic anhydride, seem t o be d e r i v e d from o x i d a t i v e l i p i d breakdown i n common w i t h the v o l a t i l e s o f many other foods and p l a n t m a t e r i a l s . Eleven of the compounds i n Table I had been i d e n t i f i e d p r e v i o u s l y i n r a i s i n s by Ramshaw and Hardy ( J _ ) . These p r e v i o u s l y i d e n t i f i e d compounds have been noted on Table I (see f o o t n o t e d ) . The r e l a t i v e q u a n t i t a t i v e p a t t e r n found i n the present work seems t o be q u i t e d i f f e r e n t from that found by Ramshaw and Hardy. T h i s d i f f e r e n c e may be due t o the method and degree of d r y i n g used. Ramshaw and Hardy analyzed A u s t r a l i a n r a i s i n s that had been d r i e d t o 10% moisture whereas C a l i f o r n i a r a i s i n s are d r i e d to ca. 14%. The A u s t r a l i a n r a i s i n s

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

Figure 1. Capillary GLC analysis of the vacuum steam volatile oil of raisins. GLC conditions are described in text.

60

TIME IN MINUTES 120 180

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

4.

BUTTERY E T A L .

Raisin and Dried Fig Volatile Components

33

TABLE I Compounds I d e n t i f i e d i n the Vacuum Steam V o l a t i l e O i l of R a i s i n s .

Peak No. Fig. I

Compound

3

C h a r a c t e r i s t i c Mass S p e c t r a l Ions b

Alkanals 1 Hexanal^ 7 Heptanal 12 Octanal 22 Nonanal 36 Decanal Alkenals 6 (E)-2-Hexenal 16 (E)-2-Heptenal 26 (E)-2-0ctenal 38 (E)-2-Nonenal 48 (E)-2-Decenal 55 (E)-2-Undecenal

44, 56, 72, 82, 67, 100 96 114 44 70 81 86

1108 1190

1.5 0.3

57, 44, 82, 112, 128, 156

1500

1.2

1230 1330 1430 1530 1630 1740

0.1 2.1 2.7 1.7 2.0 1.2

1480 110, 67, 95 95, 138, 109 1660 95, 152, 123 1740 95, 152, 123 1790

1.7 0.4 0.2 2.0

41, 41, 41, 41, 43, 41,

42, 55, 69 , 55, 83, 70 , 55, 70, 83, 70, 83, 96 , 70, 83,97 , 70, 83,97 ,

Alkadienals 34 (Ε,Ε)-2,4-Heptadienal 52 (E,E)-2,4-Nonadienal 56 (Ε,Ζ)-2,4-Decadienal 58 (Ε,Ε)-2,4-Decadienal

81, 39, 53, 81, 41,67, 81, 41,67, 81, 41,67,

d

d

Kovat's R e l . GLC % Index

83, 98 68, 112 97, 126 111, 140 110, 154 121, 168

Alkenones 14 l-0cten-3-one

55, 70, 43 97, 83, 111

1290

0.2

A l k a n o l s and A l k e n o l s 29a l-0cten-3-ol Octanol 41a 50 Nonanol 57 Decanol

57, 56, 56, 70,

72, 42, 70, 42,

85 81, 7C », 31, 42,31, 83 >, 31,

1420 1530 1630 1740

2.6 1.7 1.6 0.3

Alkanoic Acids 61 Hexanoic a c i d 64 Heptanoic a c i d 68 Octanoic a c i d 70 Nonanoic a c i d 71 Decanoic a c i d

60, 60, 60, 60, 60,

73, 73, 73, 73, 73,

57 45, 55, 87 », 45, 87, 101 55 », 85, 101, 115 45 », 115, 129, 158 45 57,129, 87, 172

1880 1990 2100 2220 2330

0.5- -4.4 0.5- -4.0 4--8.4 3--5.5 1--1.9

99, 84, 98, 97,

110 112 126 112

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

34

QUALITY OF

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FRUITS A N D

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Table I continued Terpenoids 43 (E)-2-Methy1-2,4heptadien-6-one 52 a l p h a - T e r p i n e o l 62 Geranylacetone

109, 43, 81, 53, 124, 79 59, 93, 81, 121, 136, 139 43, 69, 93, 136, 151, 19±

d

1590 1710 1850

0.1 0.4 1.4

Benzene, Naphthalene and Furan Compounds 9 2-Pentylfuran 81 29 Furfural 39 35 2-Acetylfuran 95, Π 0 , 39, 68, 53, 51 1490 1.0 36 Benzaldehyde 77, 105, 106, 51, 50, 39 1520 0.8 41, 5 - M e t h y l f u r f u r a l 110, 109, 53, 39, 81, 95 1560 2.2 47 Phenylacetaldehyde 91, 92, 120, 65, 39, 51 1650 4.0 53 Naphthalene 1_28, 64, 51, 63, 102, 77 1690 0.4-2.0 59 2-Methylnaphthalene 142, 141, 115, 71, 57.5, 63 1800 0.3 65 Dimethylnaphthalene _156, 141, 155, 115, 128, 76 2000 0.2 d

d

d

d

0

Others 69 44

2-Hexyl-3-methylmaleic anhydride 126, 43, 98, 67, 140, 196 N - E t h y l - 2 - f o r m y l p y r r o l e 123, 94, 108, 39, 66 e

a

2090 1600

f

5.0 1.0

Mass spectrum (complete spectrum) and K o v a t s GLC r e t e n t i o n index of a l l compounds l i s t e d are c o n s i s t e n t w i t h that of a u t h e n t i c samples, except f o r e. Not n e c e s s a r i l y the most i n t e n s e ions but 5 of those considered the most c h a r a c t e r i s t i c f o r t h a t compound. Ions i n descending order of i n t e n s i t y w i t h the most i n t e n s e i o n f i r s t and molecular i o n underlined. K o v a t s index f o r the Carbowax 20-M coated Pyrex c a p i l l a r y e s c r i b e d i n the experimental s e c t i o n . P r e v i o u s l y i d e n t i f i e d i n r a i s i n s by Ramshaw and Hardy, 1969. No a u t h e n t i c sample a v a i l a b l e . Mass spectrum c o n s i s t e n t w i t h p u b l i s h e d data ( 8 ) . c

f

e

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

4.

BUTTERY E T A L .

Raisin and Dried Fig Volatile Components

35

had showed a much greater r e l a t i v e amount of sugar degradation products such as f u r f u r a l and b i a c e t y l . I t i s i n t e r e s t i n g that Ramshaw and Hardy (1) i d e n t i f i e d a methylformylpyrrole whereas l - e t h y l - 2 - f o r m y l p y r r o l e was found i n the present work. Fig Volatiles. The vacuum steam v o l a t i l e o i l of d r i e d f i g amounted t o 5 ppm of the d r i e d f i g . V o l a t i l e o i l s from s e v e r a l d i f f e r e n t samples of d r i e d f i g s were i s o l a t e d and analyzed by GLC-MS. Figure I I shows a GLC a n a l y s i s of a t y p i c a l d r i e d f i g v o l a t i l e o i l . Table I I l i s t s the components i d e n t i f i e d and compares the amounts found w i t h those found i n the present work i n f r e s h f i g s of the same v a r i e t y . Mass s p e c t r a l and GLC r e t e n t i o n data o f compounds a l r e a d y l i s t e d i n Table I are not repeated Data f o r a d d i t i o n a l compounds hav The e t h a n o l , e t h y had been found i n f r e s h f i g s by previous workers ( 2 ) . These are by f a r the most abundant v o l a t i l e components i n the f r e s h f i g . In the present work these very v o l a t i l e components were analyzed (GLC-MS) u s i n g d i r e c t i n j e c t i o n of the vapor above the f i g s onto the g l a s s c a p i l l a r y column. As much as 0.5% ethanol was found i n some samples of good q u a l i t y f r e s h r i p e f i g s . There was cons i d e r a b l e v a r i a t i o n , however. Other e s t e r s reported i n the previous study (2) were not detected u s i n g the methods of the present study. The e t h a n o l , e t h y l and methyl acetates and acetaldehyde might be formed by fermentation o c c u r r i n g i n the f r e s h f i g . This fermentation i s not apparent from the appearance and f l a v o r of the f i g which appear q u i t e normal and " f r e s h " . The very v o l a t i l e fermentation components discussed above seem to be l a r g e l y l o s t i n the dry f i g . The major component o f the d r i e d f i g v o l a t i l e o i l i s benzaldehyde. Other major components i n c l u d e the a l i p h a t i c a c i d s o c t a n o i c and nonanoic a c i d s . These a c i d s were a l s o major components of r a i s i n s and have aromas reminiscent of both r a i s i n s and d r i e d f i g s . They had p r e v i o u s l y a l s o been found as major components of d r i e d almond h u l l s (7^) which i s e s s e n t i a l l y a l s o a d r i e d f r u i t . The 2-hexy-3-methylmaleic anhydride common t o r a i s i n s and d r i e d almond h u l l s ( 4 ) was not detected i n d r i e d f i g s . Unusual components found i n the d r i e d f i g v o l a t i l e o i l i n c l u d e 3-phenylpropanal (dihydrocinnamaldehyde), l i n a l o o l oxide A (2-methyl-2-vinyl-5(2'-hydroxy-2 p r o p y l ) - t e t r a h y d r o f u r a n ) , l i n a l o o l oxide C ( 5 - h y d r o x y - 2 , 6 , 6 - t r i m e t h y l - 2 - v i n y l t e t r a h y d r o pyran) and N - e t h y l - 2 - f o r m y l p y r o l l e . The l a s t compound was a l s o i d e n t i f i e d i n r a i s i n v o l a t i l e s but i n both foods the i d e n t i f i c a t i o n was only by comparison w i t h a p u b l i s h e d spectrum (8) and no a u t h e n t i c sample was a v a i l a b l e . 1

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

18

Λ7

2X

Λ0

37

3^ 31

30

26 21

16

17

TIME IN MINUTES

2?

22

2X

^

10

8

5

Figure 2. Capillary GLC analysis of the steam volatile oil of dried figs. GLC conditions are described in text.

53

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37

Raisin and Dried Fig Volatile Components

BUTTERY E T A L .

TABLE I I V o l a t i l e Components I d e n t i f i e d i n D r i e d and Fresh F i g s . Concentration i n f r e s h or d r i e d d r i e d i n f i g i n ppm Peak 1· g.

-

Compound

3

ID

2 3 8 15

-10 16 23 30 36

7-40 5 144 4 9

Alkanals Hexanal Heptana1 Octanal Nonanal

0.3 0.1 0.1 0.2

0.04 0.03 0.01 0.08

Alkenals (E)-2-Hexenal (E)-2-Heptenal (E)-2-0ctenal (E)-2-Nonenal (E)-2-Decenal (E)-2-Undecenal

0.1 0.2 0.05 0.1 0.04

-38 2a 3a 8a 22a 25

Alkanones and Alkenones 2-Hexanone 2-Heptanone 2-0ctanone (Ε,Ζ)-3,5-0ctadien-2-one (Ε,Ε)-3,5-Octadien-2-one

-

A l k a n o l s and A l k e n o l s Hexanol (Z)-3-Hexenol Heptanol

-

Fresh F i g

20

0-1

10

0-1 0-1

Rate o f weight loss, %/30 d a y s

20-30

(30

weeks)

0., 3 - 0 : ,7

11

40-70

(30

weeks)

0., 2 - 0 . ,5

6

5

30-50

(30

weeks)

0., 2 - 0 . ,5

1-3

5

10-30

(30

weeks)

0., 2 - 0 . , 5

20

20

H

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< m

Ο

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ΟΙ

H

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M

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Η

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9.

SIMON

E TA L .

Improvement of Flavor by Carrot Genetics

117

Future a c t i v i t i e s i n c l u d e the improvement of techniques f o r s e l e c t i n g q u a l i t y a t t r i b u t e s a l r e a d y i d e n t i f i e d , and t o add other a t t r i b u t e s . A f a s t e r l a b o r a t o r y method f o r s c r e e n i n g the " i s o coumarins , v o l a t i l e t e r p e n o i d s , sugar types, and c a r o t e n o i d s w i l l be v a l u a b l e . Other f l a v o r a t t r i b u t e s o f both f r e s h and processed c a r r o t s need c o n s i d e r a t i o n . The p o t e n t i a l f o r g e n e t i c improve­ ment of c a r r o t f i b e r , which i s a h i g h q u a l i t y n u t r i e n t (13) t h a t may i n f l u e n c e t e x t u r e , a l s o warrants i n v e s t i g a t i o n . With a b e t t e r knowledge of the i n h e r i t a n c e o f q u a l i t y f a c t o r s and w i t h improved methods f o r screening them, the improvement o f c u l i n a r y and n u t r i t i v e components i n a program o f c a r r o t breeding and g e n e t i c s i s f e a s i b l e . A proper p e r s p e c t i v e of q u a l i t y and marketable y i e l d must be maintained, b u t q u a l i t y c h a r a c t e r i s t i c s should be i n c l u d e d i n g e n e t i c improvement programs. 11

Abstract The improvement of raw carrot flavor requires a determination of desirable and objectionable sensory attributes, an efficient means to assess these attributes or factors related to them, and an understanding of how flavor can be altered genetically and en­ vironmentally. Using a wide range of genetic stocks grown in several environments, sensory evaluation indicated substantial variation in carrot flavor due to environmental and, to a greater extent, genetic factors. Statistical analyses suggested that volatile terpenes and sugars could account for the observed sen­ sory variation, and reconstitution experiments with authentic compounds supported these observations. Genetic experiments i n ­ dicated dominance for both mild flavor and low volatile levels, to make the use of mild-flavored inbred lines advisable in pro­ ducing hybrid carrots. Methods for screening large, segregating carrot populations for flavor improvement are available and read­ ily applicable in a carrot breeding program. Literature Cited 1. 2. 3. 4. 5. 6. 7.

Ahmed, E. M.; Dennison, R. Α.; Dougherty, R. H . ; Shaw, P. E. J. Agric. Food Chem. 1978a, 26, 192. Ahmed, Ε. M.; Dennison, R.A.; Shaw, P. E. J . Agric. Food Chem. 1978b, 26, 368. Banga, O. Euphytica 1957, 6, 54. Basker, D. Chem. Senses Flavor 1977, 2, 493. Carlson, B. C. Ph.D. Thesis, Michigan State University, MI, 1960. Carlson, B.C.;Peterson, C.E.; Tolbert, Ν. E. Plant Physiol. 1961, 36, 550. Freeman, R. E . ; Simon, P. W.; Peterson, C. E. HortScience 1980, 15, 421.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

118

8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30.

QUALITY OF SELECTED FRUITS AND VEGETABLES

Guadagni, D.C. Am. Soc. Test. Mater., Spec. Tech. Publ. 1968, 440, 36. Laferriere, L . ; Gabelman, W. H. J . Am. Soc. Hort. Sci. 1968, 93, 408. Nilsson, T. Ed., Quality of Vegetables, Acta Hort. 1979, 93. Parliment, T.H.;Kolor, M. C. J . Food Sci. 1975, 40, 762. Pyysalo, T. Z. Lebensm. Unters.-Forsch. 1976, 162, 263. Robertson, J . Α.; Eastwood, Μ. Α.; Yeoman, M. M. J . Sci. Food Agric. 1979, 30, 388. Rymal, K. S.; Rice, C. A. HortScience 1976, 11, 23. Schreier, P. C. R. C. Crit. Rev. Food Sci. Nutr. 1979, 12, 59. Schwimmer, S.; Guadagni, D. G. J . Food Sci. 1962, 27, 94. Senti, F. R.; Rizek, R. L. HortScience 1975, 10, 243. Simon, P. W.; Peterson, C. E.; Lindsay, R. C. J . Am. Soc. Hort. Sci. 1980a, 105 416 Simon, P. W.; Lindsay Chem. 1980b, 28, 549. Simon, P. W.; Peterson, C. E.; Lindsay, R. C. J . Agric. Food Chem. 1980c, 28, 559. Simon, P. W.; Peterson, C. E. HortScience 1980d, 15, 421. Sondheimer, E. J . Am. Chem. Soc. 1957, 79, 5036. Stevens, M. Α.; Frazier, W. A. Proc. Am. Soc. Hort. Sci. 1967, 91, 274. Stevens, M. Α.; Kader, Α. Α.; Albright-Holton, M.; Algazi, M. J . Am. Soc. Hort. Sci. 1977, 102, 680. U.S.D.A. Agricultural Statistics, U.S. Gov't. Printing Office (1979). Visser, T.; Schaap, Α. Α.; DeVries, D. P. Euphytica 1968, 17, 153. Visser, T.; Verhaeg, J . J . Euphytica 1978, 27, 753. Wagner, R.; Dirninger, N . ; Fuchs, V . ; Bronner, A. Int. Symp. Quality Vintage 1977, 137, S. African Minist. Agric. Williams, Α. Α.; Lea, A. G. H . ; Timberlake, C. F. Am. Chem. Soc. Symp. 1977, 51, 71. Wulf, L. W.; Nagel, C. W.; Branen, A. L. J . Agric. Food Chem. 1978, 26, 1390.

RECEIVED

April 3, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

10

Non-Bitter Hop Contributions to Beer Flavor VAL PEACOCK and MAX DEINZER Department of Agricultural Chemistry, Oregon State University, Corvallis, OR 97331

The main purpose o to the final product. A ß-acids are responsible for this taste (1). A secondary, ill de fined flavor (flavor referring to smell and taste) is also imparted to beer by brewing with "aroma hops." Not all hop varieties are considered "aroma hops," and there is evidence that the flavors imparted to beer by different aroma hops are different (2). There has been considerable controversy in recent years as to the nature and source of this flavor. Researchers have credited terpene alcohols (2, 3), humulene oxidation products (4, 5), multicyclic terpenoid ethers (6) and carotenoids (6) as being in part responsible for this flavor. Floral Hop Aroma/Taste The most easily definable hop contribution to beer aroma is a floral flavor note that certain hop varieties (not necessarily the traditional "aroma hop" varieties) impart to beer (2). Indications are (Table I) that the floral compounds linalool and geraniol are responsible for this aroma note. Geranyl isobutyrate, though present in the more floral beers, is probably in too low concentration to have a major effect on beer flavor. α-Terpineol is eliminated from consideration for the same reason. Linalool has been reported in beer at an estimated concentration of 34ppb (3) by Lindsay and at a concentration of 470ppb (7) by Tressl. As the current techniques for measuring these trace organics in beer are somewhat dubious, and considering the difficulties different investigators have in agreeing on what the sensory thresholds are for these compounds in beer (8, 9^), i t is hard to say what relative importance to beer hop aroma/taste they have. Clearly linalool must be an important contributor to this aroma/ taste even considering Meilgaard's threshold of 80ppb (8) for this compound in beer. Geraniol seems to be important only in beers brewed with certain hop varieties, whereas linalool is common to a l l the beers and hops investigated. Geraniol in hops 0097-6156/81/0170-0119$05.00/0 © 1981 American Chemical Society In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

e

---

250

100

—

100

250

100

200

75

25

--

75

--

--

200

150

500

150

-50

—

2000

e

b

e

—

500 '

—

—

—

1

10 i n water*

>40,000

36*

--

f

g

450

2000

27ppb

—

1

Threshold i n Beer

--

175

200ppb

25ppb

Hallertauer^ Beer

50

50

200

75

c

a. Commercial beer brewed w i t h 60% Cascade and 40% C l u s t e r hops. b. Commercial beer brewed w i t h a mixture o f European hops. c. A p i l o t brew made by a commercial brewery u s i n g C l u s t e r hops o n l y , d. Same as c , only u s i n g H a l l e r t a u e r hops. e. Ref. No. 4. f . Ref. No. 8. g. Ref. No. 2. h. Ref. No. 6. i . Subsequent analyses showed a t h r e s h o l d o f 2500 ppb.

Humulol

3-Eudesmol

Humulenol I I

δ-Cadinol

T-Cadinol

—

—

Caryolan-l-ol

Nerolidol

—

Humulene Epoxide I

6

50

4,4-Dimethylcrotonolactone 100

100

200

Geraniol

25

---

150

75

200ppb

--

Cluster Beer

—

200ppb

g

75

200ppb

—

European^ Mixture Beer

Isobutyrate*

e

a

Hop O i l Components Found i n Beer

Geranyl

a-Terpineol

Linalool

6

T r a n s - L i n a l o o l oxide

Compound

Cascade Beer

Table I .

10.

PEACOCK AND

DEiNZER

Non-Bitter Hop Contributions to Beer Flavor

I

IV

VII

VIII

X

XI

II

III

V

VI

121

IX

XII

Figure 1. Structures of hop oil components. Key: I, humulene; II, humulene epoxide I; III, humulene epoxide II; IV, humulol; V, humulenol II; VI, humuladienone; VII, a-eudesmol; VIII, β-eudesmol; IX, hop ether; X, karahana ether; XI, β-ionone; and XII, β-damascenone.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

122

QUALITY

OF

SELECTED

FRUITS

AND

VEGETABLES

i s v a r i e t a l s p e c i f i c . G e r a n i o l i s b e l i e v e d to be r e s p o n s i b l e f o r the much more i n t e n s e f l o r a l aroma of beers brewed w i t h Cascade hops ( 2 ) . There i s considerable disagreement as to what the sensory t h r e s h o l d of t h i s compound i s i n beer, but both major i n v e s t i g a t o r s (2, 9) r e p o r t that there i s an unusually l a r g e v a r i a t i o n of i n d i v i d u a l t h r e s h o l d s . Many persons (one-third) can perceive g e r a n i o l c o n f i d e n t l y at 25ppb and others cannot detect g e r a n i o l at even a few hundred ppb. To most people g e r a n i o l i s apparently an important aroma/taste c o n t r i b u t o r i n beer. Geranyl i s o b u t y r a t e i s an important f l o r a l hop component as i t i s b e l i e v e d that much of the compound present i n hops i s hydrolyzed to g e r a n i o l , which i s much more f l a v o r a c t i v e , during brewing ( 2 ) . T r a n s e s t e r i f i c a t i o n of hop o i l f a t t y - a c i d methyl e s t e r s to methanol and t h e i r corresponding e t h y l e s t e r s i s b e l i e v e d to take place durin fermentatio (6 10) Hydrolysi of t h i s e s t e r during fermentation p r i s i n g . The r a t i o of g e r a n i o gerany i s o b u t y r a t hopped and Cluster-hopped beers (Table I) as compared to t h e i r hop o i l s (Table I I ) tends to support t h i s i d e a . I t has been reported that fermentation of a 6% glucose s o l u t i o n w i t h 50ppm geranyl i s o b u t y r a t e added r e s u l t e d i n the h y d r o l y s i s of 15% of the e s t e r ( 2 ) . Hop storage, wort b o i l i n g and beer aging may r e s u l t i n f u r t h e r h y d r o l y s i s . As a r e s u l t , i t i s the o v e r a l l g e r a n i o l - g e r a n y l i s o b u t y r a t e content of the hop that should be considered as w e l l as the l i n a l o o l content. An attempt has been made to c o r r e l a t e the amount of t h i s f l o r a l f l a v o r one might expect from a beer brewed to the same b i t t e r n e s s l e v e l using d i f f e r e n t hop v a r i e t i e s . The y i e l d of o i l and b i t t e r i n g compounds from the hop was considered i n t h i s c o r r e l a t i o n . Cascade, Shin-shu-wase and Backa were reported as the v a r i e t i e s from which one would expect the most f l o r a l f l a v o r and P e r l e and H a l l e r t a u e r were reported to be low i n f l o r a l f l a v o r p o t e n t i a l (2). " K e t t l e Hop"

or "Noble Hop"

Aroma/Taste

" K e t t l e hop" aroma i s an i l l u s i v e f l a v o r note reminding one of hops, imparted to beer by the vigorous b o i l i n g of "aroma hops" i n the wort f o r up to a few hours. Brewers and hop f l a v o r r e searchers c u r r e n t l y do not agree on the chemical or s e n s o r i a l nature of t h i s f l a v o r note. I t i s commonly described as s p i c y or h e r b a l . There are no standard compounds used to i l l u s t r a t e t h i s f l a v o r note to f l a v o r p a n e l i s t s . This long wort b o i l i n g time i s important i n that most of the mass (80-90%) of t y p i c a l hop o i l i s made up of terpene and s e s q u i terpene hydrocarbons which are e i t h e r steam d i s t i l l e d out of the wort, polymerized or o x i d i z e d to more water s o l u b l e compounds during the process (4, _5, 11, 12). As a r e s u l t , these hydrocarbons are not found i n beer (4_, _5, _7) and t h e r e f o r e are not r e s p o n s i b l e for t h i s f l a v o r . I n v e s t i g a t o r s i n t h i s f i e l d do agree that t h i s

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

10.

PEACOCK A N D

DEiNZER

Non-Bitter Hop Contributions to Beer Flavor

123

a

Table I I . Beer F l o r a l Aroma/Taste Components i n Hops *

Hop V a r i e t y Cascade

Linalool

Geraniol

Geranyl I s o b u t y r a t e

.85

.27

1.56

.44

.24

.60

.75

.03

.12

Hallertauer

.41

n.d.

n.d.

C

.26

n.d.

n.d.

Northern Brewer

.28

.06

.12

Shin-shu-wase

.39

.37

1.08

Cluster

0

c Tettnanger Hersbrucker

Perle

Talisman

.31

.37

.95

Brewer's Gold

.41

Z>_8). Only a few n u t r i t i o n a l r e p o r t s deal w i t h immature and germinated soybeans. The primary purpose of the f o l l o w i n g s e c t i o n s i s to evaluate n u t r i t i o n a l value i n r e l a t i o n to three e d i b l e m a t u r i t y stages: immature, mature, and germinated soybeans. V i r t u a l l y a l l soybean v a r i e t i e s grown i n the United States are d e r i v e d from s i x b a s i c genetic l i n e s . P r a c t i c a l l y a l l are yellow-seeded v a r i e t i e s , which i n t u r n can be c l a s s i f i e d as

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

15.

RACKis

Comparison of Food Value of Soybeans

187

garden-type (vegetable) and f i e l d - t y p e soybeans. A t present, l i t t l e d i f f e r e n t i a t i o n can be made between garden- and f i e l d - t y p e soybeans on the b a s i s of chemical composition. C o o k a b i l i t y and p a l a t a b i l i t y ( f l a v o r and t e x t u r e ) d i f f e r e n c e s may e x i s t (2,29). Analyzed n u t r i e n t content of a mature green-seeded, vegetable-type soybean (Verde v a r i e t y ) i s c o n s i s t e n t w i t h values f o r y e l l o w seeded mature v a r i e t i e s (30,31,32). Compositional Changes During Maturation and Germination. Analyses o f f r e s h weight, percent dry matter, and c o l o r of seeds and pods i n r e l a t i o n t o days a f t e r f l o w e r i n g were evaluated f o r i n d i c e s o f degree of m a t u r i t y f o r two soybean v a r i e t i e s (21). One set o f r e s u l t s i s summarized i n Table I I . Maximum f r e s h weight f o r Hawkeye soybeans was reached a t 44 days a f t e r f l o w e r i n g , when the seeds a r e s t i l l green and pods begin to y e l l o w . Bates et a l . (33) r e f e r t o seeds harvested a t t h i s stage of m a t u r i t y as green-mature soybeans. O i l and P r o t e i n . L i p i d t r a n s f o r m a t i o n i n composition during maturation (34). As shown i n Table I I I , 90% o f the t o t a l o i l found i n mature soybeans was s y n t h e s i z e d a t the maximum f r e s h weight stage of m a t u r i t y . There are no f u r t h e r s i g n i f i c a n t changes i n s a t u r a t e : p o l y u n s a t u r a t e f a t t y a c i d r a t i o s and n u t r i t i v e value of the o i l i n green-mature and y e l l o w mature soybeans. A t the maximum f r e s h weight stage of m a t u r i t y , 61% o f p r o t e i n found i n mature soybeans was s y n t h e s i z e d (Table I V ) . On a d r y weight b a s i s , percent crude p r o t e i n increased s l i g h t l y i n going from green-mature t o dry, y e l l o w mature soybeans (35). From these data, i t appears that soybeans can be consumed i n the green-mature o r dry mature form without s i g n i f i c a n t d i f f e r e n c e s i n p r o t e i n and o i l q u a l i t y . As shown i n F i g . 1, very low amounts of e x t r a c t a b l e p r o t e i n are found a t the e a r l i e s t stages of m a t u r i t y . P r o t e i n accumulation i s v e r y r a p i d during development and reaches maximum values a t about 36 days a f t e r f l o w e r i n g , corresponding t o maximum f r e s h weight/seed. High-molecular-weight p r o t e i n s , which a r e the predominant storage p r o t e i n s i n mature soybeans, a l s o reach maximum v a l u e s 36 days a f t e r f l o w e r i n g (36,37). The r e l a t i v e amounts o f nonprotein n i t r o g e n t o p r o t e i n n i t r o g e n a r e low a t a l l stages o f m a t u r i t y (35,37). The major r e s e r v e p r o t e i n s degrade s l o w l y during germination so t h a t very l i t t l e change occurs i n the amino a c i d composition of soybean sprouts d u r i n g the f i r s t 5 days o f germination. F o r use as a v e g e t a b l e , soybeans a r e allowed t o germinate f o r only 4-6 days. That both germination and maturation do not improve the p r o t e i n q u a l i t y or e l i m i n a t e the a n t i n u t r i t i o n a l f a c t o r s i n soybeans w i l l be discussed i n the f o l l o w i n g s e c t i o n . M i n e r a l and Vitamins. M i n e r a l content, expressed on a dry-weight b a s i s , was s i m i l a r f o r f r e s h immature and f i e l d - d r i e d mature soybeans. P o s s i b l e exceptions i n c l u d e higher boron and phosphorus and lower z i n c values f o r meals prepared from mature

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

188

QUALITY OF

SELECTED

FRUITS A N D

VEGETABLES

Table I I Fresh weight, dry matter and c o l o r c h a r a c t e r i s t i c s of maturing soybeans (1969 crop year)

Average Days A f t e r Flowering

Fresh Wt., mg/seed

C o l o r of Beans

Dry Matter,

Seeds

%

Pods

16.0

Green

Green

22

30

24

59

27

131

23.0

Green

Green

29

220

23.2

Green

Green

29

295

27.6

Green

Green

31

313

28.0

Green

Green

35

384

30.0

Green

Green

40

498

32.4

Green

Green

44

568

39.0

Yellow

Light-green

49

523

42.7

Yellow

Yellow-green

52

440

49.6

Brown

Yellow

55

331

71.2

Brown

Buff-brown

253

84.1

Brown

Buff-brown

209

91.6

Brown

Buff-brown

59

C

64°

Rackis et^ a l .

b

(21), Hawkeye soybeans.

Maximum f r e s h weight occurs during the y e l l o w i n g stage. Mature beans f i e l d - d r i e d before harvest.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

19.5 20.1 22.3 23.6

64.8

100.5

179.0

186.6

214.1

324.0

452.0

311.8

39

46

63

72

R u b e l ^ t a l . (35) .

^Dry b a s i s .

a

(maturity)

44.0

39.9

20.7

12.6

4.8

15.5

30.8

146.0

32

0.03

3.5

5.5

24

0.9

Dry

Fresh

Flowering

mg/Seed

mg/Seed b Oil,%

Days A f t e r

Weight,

36.3 25.8 26.1

2.8 3.2 3.1

10.1 10.6

10.4

10.4

26.4

24.0

3.2

14.5

2.9

7.5

6.2

19.0

Oleic

Stearic

Palmitic

54.1

54.1

52.7

51.0

46.2

35.0

Llnoleic

O i l Composition, %

O i l and f a t t y a c i d composition o f Harosoy 63 soybeans during maturation*

Table I I I

5.8

6.3

7.7

9.2

12.1

30.0

Linolenic

190

QUALITY OF S E L E C T E D

FRUITS A N D

VEGETABLES

Table IV N i t r o g e n composition o f Acme soubeans during maturation

Days A f t e r

Weight

Flowering

Fresh

Dry

%

mg/Seed

25

22.2

3.8

32.2

1.2

32

124.2

27.3

31.8

8.7

41

266.3

75.7

34.1

25.6

50

370.8

122.2

34.8

42.5

60

359.4

165.6

36.0

59.6

74

238.5

200.6

35.0

70.2

(maturity)

a

R u b e l ^ t a l . (35).

^Dry b a s i s .

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

RACKis

Comparison of Food Value of Soybeans

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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QUALITY O F S E L E C T E D FRUITS A N D V E G E T A B L E S

soybeans compared w i t h meals prepared from immature soybeans (32). Only l i m i t e d data a r e a v a i l a b l e concerning the e f f e c t o f maturation and germination on the v i t a m i n and m i n e r a l content. Compiled data r e v e a l a wide range o f v a l u e s ( 2 ) . Changes i n a s c o r b i c a c i d and 8-carotene during maturation, storage and subsequent germination a r e i l l u s t r a t e d i n F i g . 2. A s c o r b i c a c i d and β-carotene i n the green-mature stage (maximum f r e s h weight/seed) a r e v e r y h i g h . Green-mature, dry mature and sprouted soybeans (5-day germination) c o n t a i n 30, 2, and 11 mg/100 gram ( f r e s h weight) a s c o r b i c a c i d , and 0.35, 0.12, and 0.2 mg/100 gram 8-carotene, r e s p e c t i v e l y (38). However, a p p r e c i a b l e amounts of a s c o r b i c a c i d and 8-carotene a r e destroyed during the cooking process needed t o maximize both p r o t e i n q u a l i t y (33) and organoleptic a c c e p t a b i l i t y (2). Carbohydrates. The amount and nature of the carbohydrates undergo e x t e n s i v e t r a n s f o r m a t i o n d u r i n g maturation and germination. As a r e s u l t very d i f f e r e n t . F l a t u l e n c been reviewed elsewhere (39). A n t i n u t r i t i o n a l F a c t o r s and P r o t e i n Q u a l i t y of Soybeans w i t h Respect t o M a t u r i t y I n the raw s t a t e , mature soybeans and many other p l a n t f o o d s t u f f s c o n t a i n protease i n h i b i t o r s t h a t d i m i n i s h the p r o t e o l y t i c a c t i v i t i e s o f t r y p s i n and chymotrypsin i n the i n t e s t i n a l t r a c t , cause p a n c r e a t i c hypertrophy and suppress growth. T r y p s i n i n h i b i t o r s (TI) account f o r about 40% o f the p a n c r e a t i c h y p e r t r o p h i c e f f e c t and g r o w t h - i n h i b i t o r y c a p a c i t y of raw soy p r o t e i n s . The r e s i s t a n c e o f the raw undenatured p r o t e i n t o t r y p t i c d i g e s t i o n accounts f o r the remaining 60%. The p r a c t i c a l s i g n i f i c a n c e o f r e s i d u a l TI a c t i v i t y i n heatprocessed soy p r o t e i n products and the b i o c h e m i c a l e f f e c t s o f o t h e r protease i n h i b i t o r s have been reviewed (40). T r y p s i n I n h i b i t o r s . T I a c t i v i t y i n 108 v a r i e t i e s and s t r a i n s o f soybeans ranged from 66 t o 233 t r y p s i n units/mg p r o t e i n (41). Mean TI v a l u e s of 57 s p e c i f i c a c t i v i t y u n i t s per mg p r o t e i n were r e p o r t e d f o r 16 f i e l d - t y p e soybeans grown i n I n d i a , whereas i n 8 vegetable-type soybeans, the mean TI v a l u e was 41 units/mg p r o t e i n (42). As shown i n Table V, TI a c t i v i t y g e n e r a l l y i n c r e a s e d d u r i n g m a t u r a t i o n . The Dare ( f i e l d - t y p e ) v a r i e t y had the g r e a t e s t i n c r e a s e i n a c t i v i t y . Dehulled immature beans h e l d 2,5 minutes i n b o i l i n g water had 97-98% of the e x t r a c t a b l e TI a c t i v i t y destroyed r e g a r d l e s s o f v a r i e t y . Germination f o r 3 days, a f t e r a 24-hour soaking p e r i o d , d i d not cause TI a c t i v i t y t o change a p p r e c i a b l y f o r the f o u r soybean v a r i e t i e s s t u d i e d (43). On the other hand, Bates e t a l . (33) r e p o r t e d t h a t TI a c t i v i t y i n water e x t r a c t s o f soybeans germinated 4 days decreased about 70% (Table V I ) . A u t o c l a v i n g f o r

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Figure 2. Ascorbic acid, β-carotene, and moisture content of mature and germi­ nated soybeans Bates and Matthews (38,). Key: - · - ·, ascorbic acid (mg/100 g fresh or soaked weight); , β-carotene (mg/100 g χ 100 fresh or soaked weight); and , moisture content.

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Table V T r y p s i n i n h i b i t o r a c t i v i t y of f o u r soybean v a r i e t i e s maturation and g e r m i n a t i o n

Time P e r i o d

3

Trypsin Inhibitor mg/g,

during

Activity,

Germination

Days

Days a t 22° C

Soylima

1

-

14.0

19.1

21.7

14.4

11

-

21

-

18.5

23.5

23.6

25.5

28

-

32

-

17.0

Mature beans

0

17.2

22.8

26.9

Soaking

1

16.5

22.6

26.9

Germinating

2

16.8

21.4

26.4

Germinating

3

16.2

20.5

25.2

Germinating

4

16.9

19.8

24.0

8

Dry-Basis

C>C

Maturation,^

Verde

6

*

Kanrich

8

Dare

27.4

a C o l l i n s and Sanders (43). b Harvesting begun e a r l y i n development w i t h seeds having h i g h moisture content and was d i s c o n t i n u e d when beans began to dry. V a r i e t i e s were not a t comparable stages of m a t u r i t y , c Values represent a c t i v i t y e x t r a c t e d under c o n d i t i o n s employed and may not represent t o t a l a c t i v i t y of the i n t a c t seed, d Trypsin i n h i b i t o r a c t i v i t y on e x t r a c t s o f d e h u l l e d immature beans decreased 97-98% a f t e r 2.5 rain i n b o i l i n g water, e Vegetable-type· f Field-type.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Table V I E f f e c t of m a t u r i t y on t r y p s i n i n h i b i t o r a c t i v i t y and heat i n a c t i v a t i o n i n soybeans

Trypsin I n h i b i t o r

b

Rate » Stage of M a t u r i t y

Raw

C

Heated

Green-mature

49.0

1.5

Mature

52.2

0.6

17.8

1.7

Sprouts

a

8

d

B t e s et a l . (33). a

b Change i n absorbance a t 257 nm/min/g p r o t e i n compared t o c o n t r o l w i t h no t r y p s i n i n h i b i t o r , Bragg v a r i e t y . C

A c t i v i t y i n 0.01N NaOH e x t r a c t s .

d

A u t o c l a v e d 121° C f o r 15 min.

e

Soaked 6 h and germinated a t 27° C

f o r 4 days.

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15 minutes a t 121°C destroyed n e a r l y a l l o f the TI's i n immature, mature and germinated soybeans. S p e c i a l mention should be made concerning the TI a c t i v i t y v a l u e s o f immature and germinated soybeans mentioned i n t h i s r e p o r t (Tables V and V I ) . T I a c t i v i t y e x t r a c t e d under these c o n d i t i o n s may not represent t o t a l a c t i v i t y of the i n t a c t bean (44,45). A l s o , much o f the T I data obtained by s e v e r a l workers cannot be compared d i r e c t l y because methodology d i f f e r e d w i d e l y and TI a c t i v i t y u n i t s a r e not interchangeable. TI a c t i v i t y i n e x t r a c t s o f immature and germinated soybeans i s r e a d i l y destroyed by a u t o c l a v i n g and other forms o f moist heat treatment. Undoubtedly, most o f the t o t a l TI i n i n t a c t immature and germinated soybeans would be r e a d i l y destroyed by heat treatment, s i n c e moisture content i s very h i g h . This c o n c l u s i o n i s d e r i v e d from the f a c t t h a t i n whole mature soybeans c o n t a i n i n g about 10% i n i t i a l m o i s t u r e , o n l y 10% o f the t o t a l t r y p s i n i n h i b i t o r a c t i v i t y was destroyed d u r i n g steamin mature soybeans were f i r s moisture content, over 97% TI a c t i v i t y was destroyed during heat treatment f o r 20 minutes (46). Other s t u d i e s on the importance of p a r t i c l e s i z e on r a t e o f d e s t r u c t i o n of TI a c t i v i t y w i t h moist heat have been r e p o r t e d by A l b r e c h t et a l . (47) and Baker and Mustakas (48). None of the animal f e e d i n g s t u d i e s w i t h immature and germinated soybeans i n c l u d e d an e v a l u a t i o n of p a n c r e a t i c enlargement (40). Maximum growth occurs i n r a t s f e d soy d i e t s i n which o n l y 79% o f the TI a c t i v i t y was e l i m i n a t e d by l i v e steam treatment, and p a n c r e a t i c hypertrophy d i d not occur w i t h only 54% d e s t r u c t i o n o f T I (49). Biochemical t h r e s h o l d l e v e l e f f e c t s i n long-term r a t f e e d i n g s t u d i e s c o n f i r m these f i n d i n g s (50). Therefore, i t i s h i g h l y u n l i k e l y t h a t p a n c r e a t i c hypertrophy would occur i n animals f e d immature and germinated soybeans, s i n c e the T I s a r e r e a d i l y destroyed by moist heat treatment. S e v e r a l d i f f e r e n t forms of protease i n h i b i t o r s have been i s o l a t e d from soybeans, and s e v e r a l g e n e t i c v a r i a n t s of the two major soy protease i n h i b i t o r s ( K u n i t z t r y p s i n i n h i b i t o r and Bowman-Birk i n h i b i t o r ) have been i d e n t i f i e d . A new form of TI immunochemically i d e n t i c a l t o the K u n i t z TI appeared during germination of s i x p o p u l a t i o n s of soybeans. These s t u d i e s have been reviewed elsewhere (40). I n s p i t e o f d i f f e r e n c e s i n l e v e l of protease a c t i v i t y and the presence of protease i n h i b i t o r v a r i a n t s , heat treatment was e f f e c t i v e i n o b t a i n i n g maximum PER and i n e l i m i n a t i n g p a n c r e a t i c hypertrophy i n soybean meals prepared from s e v e r a l v a r i e t i e s and s t r a i n s of mature soybeans (41). T

P r o t e i n Q u a l i t y . The p r o t e i n q u a l i t y of soybeans a t d i f f e r e n t stages o f m a t u r i t y i s shown i n Table V I I . Sulfur-amino a c i d content was independent of m a t u r i t y . I n the raw form, p r o t e i n q u a l i t y was very low f o r immature, mature, and germinated soybeans. A f t e r heat treatment, PER v a l u e s were increased t o

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Table V I I P r o t e i n q u a l i t y o f immature, mature and germinated soybeans (Bragg v a r i e t y )

Composition,

Protein,

Lipid,

Methionine,

Cystine,

Maturity

%

%

g/16 g Ν

g/16 g Ν

PER

Green mature, raw

36.7

20.5

1.22

0.59

0.77

Dry mature, raw

39.4

21.0

1.18

0.61

0.75

Sprouts, raw

41.7

22.3

1.19

0.63

0.64

b

Green mature, heated

2.05

Dry mature, heated

2.11

Sprouts, heated

2.02

Casein

a

2.46

0.21

2.50

B a t e s jet a l . (33) . P r o t e i n e f f i c i e n c y r a t i o c o r r e c t e d on a b a s i s of PER = 2.50

f o r c a s e i n , no s i g n i f i c a n t d i f f e r e n c e i n PER i n r e s p e c t to stage of m a t u r i t y when compared i n e i t h e r the raw or heated form.

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v a l u e s 80% o f t h a t f o r c a s e i n . The p r a c t i c a l s i g n i f i c a n c e of the heat i n a c t i v a t i o n data given i n Tables V-VII i s t h a t no s t a b l e forms o f TI e x i s t i n soybeans, r e g a r d l e s s of m a t u r i t y , and that other a n t i n u t r i t i o n a l substances t h a t may be present can be r e a d i l y e l i m i n a t e d by heat treatment o r may e x i s t a t l e v e l s that have no e f f e c t on n u t r i t i o n a l q u a l i t y as evidenced i n short-term feeding t e s t s (40,50). P r o t e i n D i g e s t i b i l i t y . The r e p o r t e d b e n e f i c i a l e f f e c t s of germination on soy p r o t e i n q u a l i t y a r e c o n f l i c t i n g and o f t e n c o n t r a d i c t o r y . Few c o n c l u s i o n s can be drawn from the l a r g e amount o f r e p o r t e d data f o r other food legumes. Some i n v e s t i g a t o r s found an i n c r e a s e i n p r o t e i n q u a l i t y and other n u t r i e n t s , others i n d i c a t e d no change o r a decrease i n n u t r i t i v e v a l u e , and s t i l l others found the data were i n c o n c l u s i v e . Some of the more d e f i n i t i v e r e f e r e n c e s on p r o t e i n q u a l i t y and d i g e s t i b i l i t y , mineral b i o a v a i l a b i l i t y i n h i b i t o r s i n c l u d e : (51-63) c i t e many r e f e r e n c e s t h a t i n d i c a t e germination of wheat may i n c r e a s e m i n e r a l a v a i l a b i l i t y , l y s i n e and s e v e r a l v i t a m i n s , improve bread q u a l i t y and s i g n i f i c a n t l y i n c r e a s e r e l a t i v e n u t r i t i v e v a l u e o f many c e r e a l s , whereas Lorenz (64) concludes l i t t l e change i n n u t r i e n t s occurs. In the i n i t i a l stages o f germination there i s a marked i n c r e a s e o f p r o t e o l y t i c enzyme a c t i v i t y i n the cotyledons o f soybeans and other food legumes, f o l l o w e d by a d e c l i n e . However, there i s no evidence t h a t the a l t e r e d amino a c i d p a t t e r n of ungerminated and 5-day germinated seeds i s enough t o a f f e c t p r o t e i n e f f i c i e n c y r a t i o s (PER) (Table V I I ) . Concomitant w i t h p r o t e o l y s i s a r e i n c r e a s e s i n nonprotein n i t r o g e n , f r e e amino a c i d n i t r o g e n , u r i c a c i d and u r e i d e n i t r o g e n i n cotyledons and embryo during germination (65,66). Since l i t t l e data i s a v a i l a b l e f o r soybeans, one must t u r n to s t u d i e s on other food legumes t o g a i n i n s i g h t on the e f f e c t s of germination on p r o t e i n q u a l i t y . D i g e s t i b i l i t y values f o r two food legumes a r e given i n Table V I I I . Germination g r e a t l y increased d i g e s t i b i l i t y of raw red kidney beans, and cooking f u r t h e r i n c r e a s e d p r o t e i n d i g e s t i b i l i t y . D i g e s t i b i l i t y values o f cooked germinated kidney beans were s i g n i f i c a n t l y higher than values f o r cooked ungerminated kidney beans (84.4 vs. 69.3%, r e s p e c t i v e l y ) . The b e n e f i c i a l e f f e c t o f germination on p r o t e i n d i g e s t i b i l i t y i s a t t r i b u t e d t o a 50% decrease i n t r y p s i n i n h i b i t o r a c t i v i t y and an i n c r e a s e i n d i g e s t i b i l i t y of the reserve storage g l o b u l i n s . On the other hand, germination appears t o lower d i g e s t i b i l i t y v a l u e s of cooked common beans. Soybeans present an i n t e r m e d i a t e p a t t e r n w i t h respect t o the e f f e c t o f germination on p r o t e i n value of the beans, i n that PER values o f ungerminated and germinated soybeans a r e not s i g n i f i c a n t l y d i f f e r e n t (Table V I I ) . Apparently, a slower p r o t e o l y t i c degradation of the major reserve p r o t e i n s i n germinating soybeans had l i t t l e e f f e c t on p r o t e i n d i g e s t i b i l i t y .

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Table V I I I D i g e s t i b i l i t y values f o r germinated

legumes and g l o b u l i n

proteins

D i g e s t i b i l i t y Values, % Cooked

Dietary Protein

Red Kidney Beans

Kidney Beans

29.5

69.3

Beans

c Casein

d

67

e

60

g

Ungerminated beans 66.4

f

84.4

Germinated beans Isolated

globulins 62.5

71.6

Ungerminated beans 73.4

f

82.6

Germinated beans Phaseolus v u l g a r i s El-Hag et a l . (63). kphaseolus v u l g a r i s , S-19N v a r i e t y E l i a s e t a l . (58). C

D i g e s t i b i l i t y v a l u e = 91.4.

d

A l l f r a c t i o n s cooked 15 min a t 121° C.

e

A l l beans cooked 10 min a t 121° C.

^10-Day germination. °9-Day germination.

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In c o n t r a s t t o most s t u d i e s , E l i a s e t a l . (58) reported that PER values i n cooked common beans (Phaseolus v u l g a r i s , v a r i e t y 5- 19n) decreased from 0.99 i n i n t a c t beans t o 0.59 and 0.26 a f t e r 6- and 9-day germination, r e s p e c t i v e l y . Apparent d i g e s t i b i l i t y v a l u e s f o r sprouted common beans decreased (Table IX) a f t e r 9 days of germination, and t r y p s i n i n h i b i t o r a c t i v i t y a l s o decreased a p p r e c i a b l y . The lower n u t r i t i v e value of germinated common beans c o r r e l a t e d w i t h a decrease i n t o t a l s u l f u r amino a c i d s (58). A f t e r 3 days o f germination, PER values decreased i n both raw and cooked forms o f green gram, cowpeas and c h i c k peas. The r e s u l t s o f s t u d i e s reviewed here, as w e l l as those reported by other workers, a r e c o n f l i c t i n g . Depending upon the food legume, germination may e i t h e r improve or decrease n u t r i t i v e value o r have l i t t l e o r no b e n e f i c i a l e f f e c t . Aside from d i f f e r e n c e s i n v a r i e t i e s and c o n d i t i o n s used i n germinating seeds, p r o t e o l y t i c a c t i v i t y d u r i n g germination i s probably the most important f a c t o r t h a t ma p r o t e i n d i g e s t i b i l i t y an e s s e n t i a l amino a c i d s , methionine, and c y s t i n e . Sprouting of c e r e a l s causes changes i n n u t r i e n t s which may not represent t r u e i n c r e a s e s but r a t h e r r e f l e c t l o s s of dry matter p r i m a r i l y as carbohydrate. Animal s t u d i e s f a i l t o show a b e n e f i c i a l e f f e c t of s p r o u t i n g on t h e n u t r i t i v e value of c e r e a l s (64). P h y t i c A c i d . Recent reviews (67,68,69) summarized the l i t e r a t u r e c o v e r i n g the r e l a t i o n s h i p between p h y t i c a c i d and m i n e r a l b i o a v a i l a b i l i t y i n soy p r o t e i n products. The formation of p h y t a t e - p r o t e i n - m i n e r a l complexes ( p a r t i c u l a r l y z i n c c h e l a t e s i n f l o u r s , c o n c e n t r a t e s , and i s o l a t e s prepared from mature soybeans) may be r e s p o n s i b l e f o r reduced m i n e r a l a v a i l a b i l i t y . However, the i r o n i n F e - l a b e l e d mature soybeans i s more a v a i l a b l e t o i r o n - d e f i c i e n t r a t s than the i r o n i n green-immature soybeans, even though mature soybeans c o n t a i n three times more p h y t i c a c i d (70). The f a c t o r ( s ) r e s p o n s i b l e f o r t h i s d i f f e r e n c e i n b i o a v a i l a b i l i t y has not been i d e n t i f i e d . Numerous animal s t u d i e s suggest t h a t b i o a v a i l a b i l i t y of m i n e r a l s from d i e t s c o n t a i n i n g h i g h phytate l e v e l s v a r i e s c o n s i d e r a b l y . Complex i n t e r a c t i o n s between the m i n e r a l s and p h y t i c a c i d contained i n f o o d s t u f f s , i n t e s t i n a l and food phytase a c t i v i t i e s , food p r o c e s s i n g c o n d i t i o n s , p r o t e i n d i g e s t i b i l i t y , and p h y s i o l o g i c a l c o n d i t i o n s i n the i n t e s t i n a l t r a c t a r e f a c t o r s that must be considered i n p r e d i c t i n g m i n e r a l b i o a v a i l a b i l i t y . D i e t a r y f i b e r along w i t h p h y t i c a c i d has been c i t e d as a p o s s i b l e cause f o r low m i n e r a l b i o a v a i l a b i l i t y of c e r e a l s and o i l s e e d s , and y e t soybean h u l l s have no s i g n i f i c a n t e f f e c t upon the a v a i l a b i l i t y o f the soy f l o u r z i n c o r o f the c a l c i u m added t o r a t s f e d soy d i e t s (71). Seed germination decreases phytate and i n c r e a s e s phytase a c t i v i t y (Table X ) . A 22% decrease i n p h y t i c a c i d occurs during 5 days o f soybean germination (62). Phytase a c t i v i t y i n soybeans i n c r e a s e d 227% compared t o an i n c r e a s e of 907-3756% i n peas. 5 9

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Table IX E f f e c t o f germination on n u t r i t i v e value of s e l e c t e d legumes

Protein Efficiency Ratios Days o f Germination

Basal

Commo

Diet

Bean

Green gram

Casein

2.32

0

0.99 ( 1 . 1 6 )

3

0.86 (1.02)

6

0.59

9

0.26

f

1.35

Cowpea

Chick Pea

2.34

2.45

(0.78) 1.55 (1.99) 2.47

1.10 (0.80) 1.20 (1.67) 2.28

Common bean E l i a s ^ t _al. (58) ; other beans Jaya et ad. (72). kphaseolus v u l g a r i s . C

Phaseolus

aureus.

^Vigna s i n e n s i s . Cicer arietinum. f Values i n parentheses represent values f o r raw beans.

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Table X Changes i n phytate content and phytase a c t i v i t y d u r i n g germination of soybeans and p e a s

Phytic Acid

b Sample

Phytase

mg Ρ

mg P/g Source

% Change

Released/g

Soybean seed

2.48

—

0.30

Soybean sprouts

1.94

22

0.68

Dwarf gray peas

1.13

—

0.04

Pea sprouts

0.59

48

0.39

E a r l y A l a s k a peas

1.86

—

0.02

Pea sprouts

1.20

35

0.65

a

a , b

% Change

227

907

3,756

Chen and Pan (62). 5-Day germination.

C

A t pH 5.2, 48 h, 37°C.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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203

P l a n t phytases have a l l o f the c h a r a c t e r i s t i c s of a n o n s p e c i f i c a c i d phosphomonoesterase w i t h broad s u b s t r a t e s p e c i f i c i t y (73). Hypercholesterolemia. D i e t has long been considered to p l a y an important r o l e i n h y p e r c h o l e s t e r o l e m i a and a t h e r o s c l e r o s i s , but most o f the emphasis has been on d i e t a r y f a t and c h o l e s t e r o l . S e v e r a l c l i n i c a l and experimental s t u d i e s demonstrate that replacement i n the d i e t of animal p r o t e i n w i t h soy p r o t e i n had a s t r i k i n g hypocholesterolemic e f f e c t (74,75). The hypocholesterolemic a c t i v i t y of many food legumes can be enhanced when germinated (76,77). Presumably an i n c r e a s e i n c e r t a i n i s o f l a v o n e s d u r i n g germination may account f o r the lowering of serum c h o l e s t e r o l l e v e l s (78). P l a n t s t e r o l s which a l s o have been i m p l i c a t e d as hypocholesterolemic d i e t a r y f a c t o r s i n c r e a s e d u r i n g germination and l a r g e changes i n t h e i r chemical composition occur (79). Estrogens. Concer l a r g e l y on consumption of r e s i d u a l d i e t h y l s t i l b e s t r o l (DES) i n animal t i s s u e fed the compound as a growth promoter. Human exposure to n a t u r a l l y - o c c u r r i n g phytoestrogens, and a d v e n t i t i o u s estrogens d e r i v e d from m i c r o b i a l organisms, i n s e c t i c i d e s , and drugs can be s u b s t a n t i a l l y higher than exposure to DES r e s i d u e s (80). The s i g n i f i c a n c e of long-term d i e t a r y exposure to estrogen i n amounts s m a l l e r than p h y s i o l o g i c a l or pharmacological doses i s highly speculative. To a v o i d hazards r e s u l t i n g from the i n g e s t i o n of n a t u r a l l y o c c u r r i n g t o x i c a n t s i n v a r i o u s f o o d s t u f f s , Coon (81) advanced the concept of " S a f e t y i n Numbers." That i s , the wider the v a r i e t y of food i n t a k e , the l e s s chance any one c o n s t i t u e n t can reach a hazardous l e v e l i n the d i e t . Another concept "Safety through Technology" can be p r a c t i c e d , by which food p r o c e s s i n g i s used t o destroy or e l i m i n a t e the t o x i c a n t . Many p l a n t s possess e s t r o g e n i c a c t i v i t y . L i t e r a t u r e on phytoestrogens can be c l a s s i f i e d i n t o three general c a t e g o r i e s : i s o f l a v o n e s , coumestans and r e s o r c y l i c a c i d l a c t o n e s (80). E s t r o g e n i c a c t i v i t y has been detected i n many f o o d s t u f f s (Table X I ) . However, the presence i n p l a n t s of s t e r o i d a l estrogens such as e s t r a d i o l , e s t r i o l , and estrone could not be confirmed by mass fragmentographic a n a l y s i s (82). E s t r o g e n i c a c t i v i t y i s based mostly on evidence of u t e r i n e enlargement or o f c o r n i f i c a t i o n of v a g i n a l e p i t h e l i u m i n experimental animals. Coumestrol content of p l a n t f o o d s t u f f s i s given i n Table X I I . The 8- to 197-fold i n c r e a s e i n coumestrol c o n c e n t r a t i o n w i t h germination time may r e f l e c t inherent v a r i e t a l d i f f e r e n c e s and environmental c o n d i t i o n s d u r i n g the growing season, as w e l l as m i c r o b i a l e f f e c t s . Whether these f a c t o r s o r the methodology employed f o r germination may e x p l a i n the wide d i f f e r e n c e s i n reported v a l u e s f o r coumestrol content i n soybean sprouts by Knuckles et a l . (83) and Lookhart et a l . (84) remains to be evaluated. D e h u l l i n g ungerminated and germinated soybeans can

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Table X I E s t r o g e n i c a c t i v i t y of common p l a n t f o o d s t u f f s

Foodstuff

Amount

Carrots, fres b

Cabbage

0.024 yg E / g

Peas

0.004-0.006 yg E / g

Hops

1-300 yg E / g

2

2

2

Wheat bran

+

Wheat germ

+

R i c e bran

+

Rice p o l i s h

+

Soybean meal

+

Vegetable o i l s

+

Pomegranate seeds

4-17 mg estrone/kg

Milk

+

a

Compiled by Verdeal and Ryan (80)

from v a r i o u s b

E

0

sources.

= 17-3-estradiol.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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RACKIS

Table X I I Coumestrol content o f p l a n t products

Coumestrol, ppm, Dry B a s i s Product

A

a

A l f a l f a sprouts

5.0

Soybean sprouts

71.1

b

B

C

0.23--3.94 '

Soybeans Soybean meal ( d e f a t t e d )

0.4

-

Soy p r o t e i n concentrate

0.2

-

Soy p r o t e i n i s o l a t e

0.6

-

Green beans (frozen)

1.0

-

Snow peas (frozen)

0.6

-

Green peas (frozen)

0.4

B r u s s e l l sprouts

0.4

-

Red beans

0.4

-

S p l i t peas

0.3

-

Spinach l e a f ( f r o z e n )

0.1

-

a

K n u c k l e s ^ t a l . (83) .

b

Lookhart et a l . (84). Values f o r three v a r i e t i e s , c o r r e c t e d f o r the

36% u n e x t r a c t a b l e coumestrol Lookhart e t a l . ( 8 5 ) . d

Some v a r i e t i e s c o n t a i n much higher l e v e l s

(Lookhart p e r s o n a l communication).

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Q U A L I T Y O F S E L E C T E D FRUITS A N D V E G E T A B L E S

reduce t o t a l coumestrol content 37-63% (85). Coumestrol content of commercial f l o u r s from germinated and ungerminated soybeans has been r e p o r t e d (86). As i n d i c a t e d i n Table X I I I , human exposure to soybean i s o f l a v o n e s , measured i n DES e q u i v a l e n t s , i s c o n s i d e r a b l y more l i k e l y than exposure t o coumestrol i n soybeans. S e v e r a l f o l d i n c r e a s e s i n i s o f l a v o n e content during germination i s a d e f i n i t e p o s s i b i l i t y . The importance of soybean estrogens, p a r t i c u l a r l y i n germinated soybeans, i n the e t i o l o g y of d e l e t e r i o u s r e a c t i o n s i n humans needs more study. Soybean i s o f l a v o n e s and p h e n o l i c a c i d s probably account f o r the a n t i o x i d a n t a c t i v i t y of soybeans, d e f a t t e d soy f l o u r , p r o t e i n concentrates, and i s o l a t e s ( 8 9 ) . Ohta e t a l . (90) i s o l a t e d two new i s o f l a v o n e s from soybeans, one of which was i d e n t i f i e d as 6"-0-acetyl d a i d z i n ; g l y c i t e i n and g l y c i t e i n - 7 - 0 - g l u c o s i d e , which were i s o l a t e d by Nairn et a l . ( 8 7 ) , were not detected by these workers. Conclusions Although many food legumes i n the immature, mature, and germinated stages can vary w i d e l y i n n u t r i t i v e v a l u e , no r e a d i l y apparent i n f o r m a t i o n can account f o r the f a c t that n u t r i t i v e v a l u e , and p r o t e i n q u a l i t y i n p a r t i c u l a r , can e i t h e r i n c r e a s e , decrease, o r remain the same. On the other hand, p r o t e i n q u a l i t y of immature, mature, and germinated soybeans i s not s i g n i f i c a n t l y d i f f e r e n t when p r o p e r l y processed w i t h moist heat treatment. To e l i m i n a t e the g r o w t h - i n h i b i t i n g and p a n c r e a t i c h y p e r t r o p h i c e f f e c t s o f raw soybeans, r e g a r d l e s s of the s t a t e of m a t u r i t y , cooking i s r e q u i r e d to i n a c t i v a t e protease i n h i b i t o r s and convert raw p r o t e i n s i n t o more r e a d i l y d i g e s t i b l e forms. There may be some n u t r i t i o n a l b e n e f i t s i n consuming immature and germinated soybeans compared to products prepared from mature soybeans. For example, a s c o r b i c a c i d and (3-carotene a r e present i n r a t h e r h i g h amounts i n immature and germinated soybeans, whereas mature soybeans a r e p r a c t i c a l l y devoid of these v i t a m i n s . Content of some of the other v i t a m i n s and minerals may d i f f e r a p p r e c i a b l y , but the general composition of soybeans a t the three stages of m a t u r i t y i s e s s e n t i a l l y the same. B e t t e r cooking and t a s t e c h a r a c t e r i s t i c s are the main advantages o f d i r e c t consumption of green-immature and germinated soybeans as a vegetable. Mature soybeans r e q u i r e long cooking times t o make them tender. Organoleptic q u a l i t i e s of immature beans a r e reported t o be much b e t t e r than those of mature soybeans o r of f l o u r s , concentrates, and i s o l a t e s prepared from them. F l o u r s from germinated soy beans may have b e t t e r bread-making p r o p e r t i e s than f l o u r s made from mature soybeans. The n u t r i t i o n a l p r o p e r t i e s of acceptable foods from soybeans at v a r i o u s stages of m a t u r i t y should encourage the development of soybeans as an important and v e r s a t i l e i n t e r n a t i o n a l p r o t e i n resource. Present world p r o d u c t i o n of soybeans, i f used d i r e c t l y f o r human consumption, can supply 1.4 b i l l i o n people w i t h the

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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Table X I I I Human exposure t o exogenous

estrogens Estimate of P o s s i b l e D a i l y Dose (yg/DES

Estrogen Source

Equivalents)

pill

50,000

Birth control p i l l

2,500

Morning-after

b

b

100 g Beef l i v e r w i t h 0. b

100 g Wheat w i t h 2 ppm zearalenone

0.2

100 g Beans (Phaseolus v u l g a r i s ) w i t h 210 ppb e s t r a d i o l

0.03-0.15

20 g (Dry b a s i s ) soybean sprouts w i t h 70 ppm coumestrol

0.5

Soybeans w i t h 1.2 ppm coumestrol

0.0085

b c 100 g Soybean meal w i t h 164.4 mg genistin c 100 g soybean meal w i t h 1.4 mg g e n i s t e i n 9

b

1.64

d

0.014 0.04

100 g Soybean meal w i t h 58.1 mg° d a i d z i n c

d

d

0.0045

100 g Soybean meal w i t h 0.6 mg d a i d z e i n

b

d

c 100 g Soybean meal w i t h 0.11 mg g l y c i t e i n 100 g Soybean meal w i t h 33.8 mg g l y c i t e i n - 7 3-0-glucoside

a

DES = d i e t h y l s t i l b e s t r o l .

b

C o m p i l e d by Verdeal and Ryan (80).

C

Naim et a l . (87) .

^ C a l c u l a t e d according t o r e l a t i v e potency i n mice B i c k o f f et a l . (88). E s t r o g e n i c potency unknown.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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a

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recommended d a i l y allowance of 56 g p r o t e i n f o r a 70-kg man. I n a d d i t i o n t o the n u t r i t i o n a l data reviewed, i t i s necessary t o c o n s i d e r the d i f f i c u l t i e s of h a r v e s t i n g and s t o r i n g immature soybeans. S p e c i a l h a r v e s t i n g and s h e l l i n g equipment i s needed to prevent damage (91,92). Costs a s s o c i a t e d w i t h germination and s p o i l a g e problems d u r i n g storage of immature soybeans a l s o are important c o n s i d e r a t i o n s . More research i s needed t o e s t a b l i s h o p t i m a l c o n d i t i o n s of germination i n order to provide products w i t h acceptable f u n c t i o n a l and o r g a n o l e p t i c p r o p e r t i e s . Germination c o n d i t i o n s can a d v e r s e l y a f f e c t germination a c t i v i t y and v i g o r , f l a v o r , m i c r o b i a l a c t i v i t y , and wholesomeness of the f i n a l product (23,24).

Literature Cited 1.

2. 3. 4.

5.

6. 7. 8. 9.

10. 11. 12.

WOLF, W. J. in "The World Soybean Research Conference II, Proceedings" (F. T. Press, Inc., Boulder, RACKIS, J. J. in "Postharvest Biology and Biotechnology." (H. O. Hultin and M. Milner, eds.), pp. 34-76. Food and Nutrition Press, Inc., Westport, Connecticut. (1978) WOLF, W. J. in "Proc. Int. Soya Protein Food Conf.," Singapore, January 25-27, pp. 59-65. American Soybean Association. (1978) WILCKE, H. L.; HOPKINS, D. T. and WAGGLE, D. H. (eds.). "Soy Protein and Human Nutrition," Academic Press, New York. (1979) SARETT, H. P. in "World Soybean Research." Proceedings of World Soybean Research Conference, (L. D. Hill, ed.), pp. 840-849. The Interstate Printers and Publishers, Inc., Danville, Illinois. (1976) YOUNG, V. R.; SCRIMSHAW, N. S.; TORUN, B.; VITERI, F. J. Am. Oil Chem. Soc. 1979, 56, 110-120. SMITH, A. K. and CIRCLE, S. J. (eds.). "Soybeans: Chemistry and Technology, Vol. II, Proteins." Avi Publishing Co., Westport, Connecticut. (1979) AMERICAN SOYBEAN ASSOCIATION. "Proceedings of the World Soy Protein Conference," Munich, Germany, November 11-14, 1973. J. Am. Oil Chem. Soc. (1974) 51, 49A-207A. AMERICAN OIL CHEMISTS' SOCIETY. "Proceedings World Conference on Vegetable Food Proteins," Amsterdam, The Netherlands, October 29-November 3, 1978. J. Am. Oil Chem. Soc. (1979) 56, 99-483. RACKIS, J. J. in "Tropical Foods: Chemistry and Nutrition," Vol. 2. (G. E. Inglett and G. Charalambous, eds.), pp. 485510. Academic Press, New York. (1979) PHILLIPS, R. L. Cancer Lett. 1979, 35, 3513-3522. HESSELTINE, C. W.; WANG, H. L. in "Soybeans: Chemistry and Technology, Vol. I, Proteins." (A. K. Smith and S. J. Circle, eds.), pp. 389-419. Avi Publishing Co., Westport, Connecticut. (1972)

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

15. RACKIS Comparison of Food Value of Soybeans

13.

14. 15.

16. 17.

18.

19.

20.

21. 22. 23.

24. 25. 26.

27.

28.

29. 30.

AMERICAN SOYBEAN ASSOCIATION. "Proceedings of the International Soya Protein Food Conference," Singapore, January 25-27, 1978. American Soybean Association, St. Louis, Missouri. (1978) SHURTLEFF, W. and AOYAGI, A. (eds.). "The Book of Tempeh." Harper and Row Publishers, Inc., New York. (1979) SHURTLEFF, W. and AOYAGI, A. (eds.). "Tofu and soymilk production. The Book of Tofu," Vol. II, New-Age Foods Study Center, Lafayette, California. (1979) BAUER, C.; ANDERSON, J. (eds). "The Tofu Cookbook," Rodale Press, Emmaus, Pennsylvania. (1979) LEVITON, R. (ed.). Soyfoods-The. Journal of the Soycrafters Association of North America, Ashuelot Valley Printing, Keene, New Hampshire. PROTEIN ADVISORY GROUP OF THE UNITED NATIONS. PAG Statement No. 22, PAG Bulletin Vol III, No 2 United Nations, Ne WATANABE, T. i n "Proc January 25-27, American Soybean Association, (1978), pp. 3538. NATIONAL RESEARCH COUNCIL. "Recommended Dietary Allowances," 8th revised edition, National Academy of Science, Washington, D.C. (1974) RACKIS, J. J.; HONIG, D. H.; SESSA, D. J.; MOSER, H. A. Cereal Chem. 1972, 49, 586-597. POMERANZ, Y.; SHOGREN, M. D.; FINNEY, K. F. J. Food S c i . 1977, 42, 824-827, 842. FINNEY, P. L. i n "Nutritional Improvement of Food Proteins." (M. Friedman, ed.), Advances in Experimental Medicine and Biology Series, Vol. 105, Plenum Press, New York. (1979) HSU, D.; LEUNG, H. K.; FINNEY, P. L.; MORAD, M. M. J. Food Sci. 1980, 45, 87-92. FINNEY, P. L.; MORAD, M. M.; HUBBARD, J. D. Cereal Chem. i n press. AGENCY FOR INTERNATIONAL DEVELOPMENT. Food for Peace, PL-480, T i t l e II, Commodities Reference Guide, U.S. Department of State, Washington, D.C, November 15. (1976) AGENCY FOR INTERNATIONAL DEVELOPMENT. An inventory of information on the u t i l i z a t i o n of unprocessed and simply processed soybeans as human food. Contract AID/AG/TAB-22512-76. U.S. Department of State, Washington, D.C. (1976) BRESSANI, R.; ELIAS, L. G. in "New Protein Foods." (A. M. Altschul, ed.), pp. 230-297. Vol. 1A, Technology, Academic Press, New York. (1974) PERRY, A. K.; PETERS, C. R.; VAN DUYNE, F. O. J. Food S c i . 1976, 41, 1330-1334. CRITTENDEN, H. W.; RAHN, E. M.; WISK, E. L.; WOODMAN, G. W. The Verde Soybean. Del. Agric. Exp. Sta. Cire. No. 9. (1968)

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31. SVEC, L. in "Final Report—An Interdisciplinary Program on the C h a r a c t e r i z a t i o n and E v a l u a t i o n of E d i b l e Green Seeded Soybeans." (P. R. A u s t i n , ed.) U n i v e r s i t y of Delaware Research Foundation, Newark, Delaware. (1970) 32. RASMUSSEN, A. I . J . Am. D i e t . Assoc. 1978, 72, 604-608. 33. BATES, R. P.; KNAPP, F. W.; AVAUJO, P. E. J . Food S c i . 1977, 42, 271-272. 34. PRIVETT, 0. S.; DOUGHERTY, Κ. Α.; ERDAHL, W. L.; STOLYHEVO, A. J . Am. Oil Chem. Soc. 1973, 50, 516-520. 35. RUBEL, Α.; RINNE, R. W.; CANVIN, D. T. Crop Sci. 1972, 12, 739-741. 36. HILL, J. E.; and BREIDENBACH, R. W. P l a n t P h y s i o l . 1974, 53, 742-746. 37. HILL, J. E.; BREIDENBACH, R. W. P l a n t P h y s i o l . 1974, 53, 747-751. 38. BATES, R. P.; MATTHEWS R F Proc F l a State Hort Soc 1975, 88, 266-271 39. RACKIS, J. J. J 40. RACKIS, J. J.; GUMBMANN, M. R. i n " A n t i n u t r i e n t s and N a t u r a l T o x i c a n t s . " (R. L. Ory, e d . ) , Chapter 12. Food and Nutrition P r e s s , I n c . , Westport, Connecticut. (1981) 41. KAKADE, M. L.; SIMONS, N. R.; LIENER, I . E.; LAMBERT, J. W. J . A g r i c . Food Chem. 1972, 20, 87-90. 42. GUPTA, A. K.; DEODHAR, A. D. Indian J . Nutr. D i e t . 1975, 12, 81-84. 43. COLLINS, J . L.; SANDERS, G. G. J . Food Sci. 1976, 41, 168-172. 44. RACKIS, J . J.; McGHEE, J. E.; LIENER, I . E.; KAKADE, M. L.; PUSKI, G. C e r e a l Sci. Today 1974, 19, 513-516. 45. KAKADE, M. L.; RACKIS, J . J.; McGHEE, J. E.; PUSKI, G. C e r e a l Chem. 1974, 51, 376-382. 46. RACKIS, J . J. J . Am. Oil Chem. Soc. 1974, 51, 161A-174A. 47. ALBRECHT, W. J.; MUSTAKAS, G. C.; McGHEE, J. E. C e r e a l Chem. 1966, 13, 400-407. 48. BAKER, E. C.; MUSTAKAS, G. C. J . Am. Oil Chem. Soc. 1973, 50, 137-141. 49. RACKIS, J . J.; McGHEE, J. E.; BOOTH, A. N. C e r e a l Chem. 1975, 52, 85-92. 50. RACKIS, J. J.; McGHEE, J. E.; GUMBMANN, M. R.; BOOTH, A. N. J . Am. Oil Chem. Soc. 1979, 56, 162-168. 51. EVERSON, G. J.; STEENBOCK, H.; CEDERQUIST, D. C.; PARSONS, H. T. J . Nutr. 1944, 27, 225-229. 52. MATTINGLY, J. P.; BIRD, H. R. P o u l t r y Sci. 1945, 24, 344352. 53. DESIKACHAR, H. S. R.; DE, S. S. Science 1947, 106, 421-422. 54. CHATTAPADHGAY, H. S.; BANNERJEE, S. Indian J. Med. Res. 1953, 41, 185-189. 55. KAKADE, M. L.; EVANS, R. J. J . Food Sci. 1966, 31, 781-783. 56. ABU-SHAKRA, S.; MIRZA, S.; TANNOUS, R. J . ISci. Food A g r i c . 1970, 21, 91-93.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

15. RACKIS Comparison of Food Value of Soybeans 57. 58.

211

PUSZTAI, A. P l a n t a 1972, 107, 121-129. ELIAS, L. G.; CONDE, Α.; MUNZ, Α.; BRESSANI, R. i n "Nutritional Aspects o f Common Beans and Other Legume Seeds as Animal and Human Foods." (W. G. J a f f e e , e d . ) , pp. 139163. A r c h i v o s Latinoamericanos de N u t r i c i o n , Caracas, Venezuela (1973) 59. PALMER, R.; McINTOSH, Α.; PUSZTAI, A. J . Sci. Food A g r i c . 1973, 24, 937-944. 60. CHEN, L. H.; WELLS, C. E.; FORDHAM, J. R. J . Food Sci. 1975, 40, 1290-1294. 61. FORDHAM, J. R.; WELLS, C. E.; CHEN, L. H. J . Food Sci. 1975, 40, 552-556. 62. CHEN, H.; PAN, S. H. Nutr. Rep. I n t . 1977, 16, 125-131. 63. EL-HAG, N.; HAARD, N. S.; MORSE, R. E. J . Food Sci. 1978, 43, 1874-1875. 64. LORENZ, K. CRC Critical Reviews in Food Science and N u t r i t i o n 1980, 13 65. THAPAR, V. K.; PAUL 1, 11-15. 66. CHEN, L. H.; THACKER, R. J . Food Sci. 1978, 43, 1884-1885. 67. RACKIS, J. J.; ANDERSON, R. L. Food Prod. Dev. 1977, 11(10), 38, 40, 44. 68. ERDMAN, Jr., J. W. J . Am. Oil Chem. Soc. 1979, 56, 736-741. 69. CHERYAN, M. CRC Critical Reviews in Food Science and Nutrition 1980, 13, 297-336. 70. WELCH, R. M.; CAMPEN, D. R. J . Nutr. 1975, 105, 253-256. 71. WEINGARTNER, Κ. E.; ERDMAN, Jr., J. W.; PARKER, Η. M.; FORBES, R. M. Nutr. Rep. I n t . 1979, 19, 223-231. 72. JAYA, T. V.; KRISHNAMURTHY, K. S.; VANKATARAMAN, L. V. Nutr. Rep. I n t . 1975, 12, 175-183. 73. LOLAS, G. M.; MARKAKIS, P. J . Food Sci. 1977, 42, 10941097, 1106. 74. SIRTORI, C. R. et al. Am. J . Clin. Nutr. 1979, 32, 16451658. 75. CARROLL, Κ. K.; HUFF, M. W.; ROBERTS, C. K. i n "Soy P r o t e i n and Human Nutrition." (H. L. W i l c k e , D. T. Hopkins, D. H. Waggle, eds.), pp. 261-280. Academic P r e s s , New York. (1979) 76. JAYA, T. V.; VENKATARAMAN, L. V. Nutr. Rep. I n t . 1979, 20, 383-392. 77. JAYA, T. V.; VENKATARAMAN, L. V.; KRISHNAMURTHY, K. S. Nutr. Rep. I n t . 1979, 20, 371-381. 78. SHARMA, R. D. L i p i d s 1979, 14, 535-540. 79. YOSHIDA, H.; KAJIMOTO, G. A g r i c . Biol. Chem. 1979, 43, 705712. 80. VERDEAL, K.; RYAN, D. S. J . Food P r o t . 1979, 42, 577-583. 81. COON, J. M. i n "Toxicants o c c u r r i n g n a t u r a l l y i n foods," 2nd Ed. Committee on Food P r o t e c t i o n , Food and Nutrition Board. N a t i o n a l Research C o u n c i l , N a t i o n a l Academy of Science, pp. 573-594. Washington, D.C. (1973)

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

212

82. 83. 84. 85. 86.

87. 88. 89. 90. 91. 92.

QUALITY OF SELECTED FRUITS AND VEGETABLES

VAN ROMPUY, L. L. L.; ZEEVAART, J. A. D. Phytochemistry 1979, 18, 863-865. KNUCKLES, B. E.; de FREMERY, D.; KOHLER, G. O. J . A g r i c . Food Chem. 1976, 24, 1177-1180. L00KHART, G. L.; FINNEY, P. L.; FINNEY, K. F. C e r e a l Chem. 1979, 56, 495-496. L00KHART, G. L.; JONES, B. L.; FINNEY, K. F. C e r e a l Chem. 1979, 56, 386-388. LOOKHART, G. L.; FINNEY, K. F.; FINNEY, P. L. i n " L i q u i d Chromatography." (G. Charalambous, ed.), pp. 129-138. Academic P r e s s , New York. (1979) NAIM, M.; GESTETNER, B.; ZILKAH, S.; BIRK, Y.; BONDI, A. J . A g r i c . Food Chem. 1974, 22, 806-810. BICKOFF, Ε. M.; LIVINGSTON, A. L.; HENDRICKSON, A. P.; BOOTH, A. N. J . A g r i c . Food Chem. 1962, 10, 410-412. PRATT, D. E.; BIRAC P M J Food Sci. 1979 44 1720-1722 OHTA, N.; KUWATA, Biol. Chem. 1979, 43, COLLINS, J . L.; Mc CARTY, I . E. Tenn. Home Sci. Prog. Rep. No. 69, 1969, K n o x v i l l e , Tenn., pp. 1-4. COLLINS, J . L.; Mc CARTY, I . E.; SWINGLE, H. D. Tenn. Home Sci. Prog. Rep. No. 78, 1971, K n o x v i l l e , Tenn., pp. 1-4.

RECEIVED April 15,

1981.

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

16 Lipid Oxidation in Fruits and Vegetables ROLAND TRESSL, DAOUD BAHRI, and KARL-HEINZ ENGEL Technische Universität Berlin, Seestrasse 13, D-1000 Berlin 65, West Germany

The enzymic formatio hols, and oxoacids (fro on d i s r u p t i o n of plant tissues i s an important b i o synthetic pathway by which f r u i t and vegetable volatiles are formed. Some examples are: (E)-2-hexenal ("leaf aldehyde") and (Z)-3-hexenol ("leaf alcohol") i n tea; (E)-2-hexenal in apples; (Ε,Ζ)-2,6-nonadienal ("violet leaf aldehyde") and (E)-2-nonenal in cucumber; (Z)-6-nonenal in musk melon; (Ζ,Ζ)-3,6-nonadienol i n water melon, and 1-octen-3-ol ("mushroom alcohol") i n c e r t a i n edible mushrooms and Fungi. The enzyme system i s highly substrate s p e c i f i c to a (Ζ,Z)1,4-pentadiene system ( l i k e lipoxygenase) s p l i t t i n g the >C = C< double bond at the W - 6 and/or W - 9 p o s i t i o n . There­ fore l i n o l e i c - , l i n o l e n i c - , and arachidonic acids are natural substrates. I t seems to be a common p r i n c i p l e i n leaves, f r u i t s , vegetables, and basidiomycetes. Some of the v o l a t i l e s formed are known as important aroma components, pheromonones or wound hormones. In 1966 our experiments with f r u i t homogenates showed that l i n o l e n i c acid i s transformed into (Z)3hexenal, (E)-2-hexenal and the corresponding alcohols. By means of radio l a b e l i n g experiments with r i p e bananas we could demonstrate that the precursor i s converted into (E)2-hexenal and 12-oxo-(E)-10-dodecenoic acid. Green bananas decomposed ( U - C ) l i n o l e n i c acid into (Ε,Z)-2,6-nonadienal and 9-oxononanoic acid (1,2). 14

F i g u r e 1 shows Cg-, C 9 - , C 3 - , C-|o~/ ^ 12" components which a r e formed from l i n o l e n i c a c i d i n c e r ­ t a i n p l a n t s , f r u i t s , v e g e t a b l e s , and mushrooms. There a r e n o r m a l l y f o u r enzymes i n v o l v e d which seem t o be membrane bonded and l o c a t e d i n t h e c h l o r o p l a s t s . I n 1970 we t r i e d t o i s o l a t e and c h a r a c t e r i z e t h e s e e n ­ zymes and c o u l d demonstrate t h a t l i p o x y g e n a s e ( E l ) , an a n c

c

0097-6156/81/0170-0213$05.00/0 © 1981 American Chemical Society In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

214

QUALITY

OF

SELECTED

FRUITS

AND

VEGETABLES

a l c o h o l o x i d o r e d u c t a s e (E4) , and a (Z) -3 / ( E ) - 2 - i s o merase (E3) a r e o p e r a t i v e i n r i p e and g r e e n bananas and a p p l e s . We f a i l e d t o i s o l a t e an a c t i v e enzyme E2 c o n v e r t i n g the 13-L00H i n t o h e x e n a l (and C-j 2~°xoacid) o r 13-LnOOH i n t o (ZJ-3-hexenal and ( E ) - 2 - h e x e n a l . T h i s was p r e t t y f r u s t r a t i n g because t h e enzyme E2 showed a v e r y h i g h a c t i v i t y i n homogenates and t i s s u e s l i c e s b u t no a c t i v i t y a t a l l i n the i s o l a t e s . We s t o p p e d our e x p e r i m e n t s and c a l l e d E2 = "aldehyde l y a s e " . In 1976 V i c k and Zimmerman (_3) demonstrated a " h y d r o p e r o x i d e l y a s e " a c t i v i t y i n water melon s e e d l i n g s and i n 1977 1978 G a l l i a r d and coworkers (_4, 5, 6) c h a r a c t e r i z e d a " h y d r o p e r o x i d e c l e a v i n g enzyme" from f r u i t s o f cucum­ b e r s and tomatoes. The c l e a v i n g enzyme E2 was l o c a t e d i n the c h l o r o p l a s t s and o t h e r s u b c e l l u l a r membranes and l o s t i t s a c t i v i t durin p u r i f i c a t i o n 13 d 9-L00H were good s u b s t r a t e hydroxy a c i d s o r ketols and coworkers (]_) i n v e s t i g a t e d an enzyme system i n Thea s i n e n s i s c h l o r o p l a s t s which c o n v e r t e d ( U - 1 4 c ) l i n o l e n i c a c i d i n t o {Z)-3-hexenal, (E) -2-hexenal, and 12- oxo-(^Z)-9-, and 1 2-oxo- (E)-10-dodecenoic acids. (Ζ,Ζ)-3,6-nonadienoic a c i d was a l s o c o n v e r t e d i n t o (Z)-3-hexenal. Therefore E i n Thea c h l o r o p l a s t s seems t o be no l i p o x y g e n a s e system. Many p l a n t s (and f r u i t s ) p o s s e s s l i p o x y g e n a s e but no c l e a v i n g enzymes E2. The hydroperoxides are converted i n t o carbonyls, a l c o h o l s , and o x o a c i d s by c h e m i c a l r e a c t i o n s (examples: cooked asparagus, p o t a t o e s , m a l t ) . The p r o d u c t s i n t h e s e systems a r e comparable t o t h o s e o f the a u t o x i d a t i o n o f fatty acids. 2

F o r m a t i o n o f C a r b o n y l s and Oxoacids Reactions

by

Chemical

Thermal o x i d a t i o n , a u t o x i d a t i o n , and l i g h t i n d u c e d o x i d a t i o n w i t h o u t s e n s i t i z e r produce 9- and 13-L00H from l i n o l e i c a c i d , which a r e decomposed t o h e x a n a l , 13- O X O - 9 , 1 1 - t r i d e c a d i e n o i c a c i d , 9-oxononanoic a c i d , c a p r y l i c a c i d , and 2 , 4 - d e c a d i e n a l s as major components. T h i s i s demonstrated i n F i g u r e 2 and T a b l e I . M e t h y l l i n o l e a t e was d i s s o l v e d i n e t h a n o l / w a t e r and i r r a d i a ­ t e d w i t h l i g h t a t 25°C i n t h e p r e s e n c e o f oxygen du­ r i n g 5 t o 20 h r . The v o l a t i l e s were i s o l a t e d and i n ­ v e s t i g a t e d by c a p i l l a r y gas chromatography-mass s p e c ­ t r o m e t r y , and p r e p a r a t i v e gas c h r o m a t o g r a p h y - i n f r a r e d s p e c t r o s c o p y . The r e s u l t s and methods used w i l l be p u b l i s h e d i n d e t a i l ( B a h r i and T r e s s l , 1981) . S i m i l a r r e s u l t s were r e c e n t l y p r e s e n t e d by Chan e t a l . (_8) who i n j e c t e d 13- and 9-L00H i n the i n j e c t i o n p a r t o f a

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

16.

Lipid Oxidation in Fruits and Vegetables

TRESSL E T A L .

215

12-0X0-(Z)-9-D0DECEN0IC ACID [Î0-0X0- (E) -8jDECE_N0IC _AÇIDJ 9-0X0N0NAN0IC ACID LINOLENIC ACID CH-,CH CH=CH-CH -CH=CH-;CH -CH=CH- (CH ) -CCX)H 0

0

0

2

?

I (Z)-3-HEXENAL (Ε)-2-HEXENAL : ( Ζ,Z)-3,6-NONADIENAL. ;: (Ε,Z)-2,6-NONADIENAL: I 1,5-0CTADIEN-3-0NE I 1 5-0CTADIEN-3-0 I 2,5-0CTADIEN-1-O /

Figure 1.

Figure 2.

Various components formed from linolenic acid in certain plants, fruits, and vegetables

Thermal oxidation, autoxidation, and light-induced oxidation without sensitizer

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

216

QUALITY

Table I

OF SELECTED

FRUITS A N D V E G E T A B L E S

F o r m a t i o n o f V o l a t i l e s by L i g h t Induced O x i d a t i o n o f M e t h y l L i n o l e a t e (ML) I CW2QM ML+( 0 ) MLH- OO2) Precursor (OV 101) ug/mg ML ug/mg ML MLOOH 3

K

Component

2

1

Hexanal

1060

3,8

5,4

13-ML00H

2

2-Pentylfuran

1205

0,73

1,6

1O-ML0OH

3

1-0cten-3-on

1286

-

0,4

1O-ML0OH

4

(E)-2-Heptenal

1296

1,38

13,8

12HVIL00H

1372

9,6

13,8

9-MLOOH

7 2-Octenal 3- Nonenal

1404 1414

0,2

2,3 0,7

10-MDOOH 1O-ML00H

8 2-Nonenal

1510

0,08

0,48

1CHVIL00H

5 Methyl caprylate 6

1-0cten-3-ol

9

(E,Z) -2,4-Decadienal

1743

2,8

4,0

9-^L00H

10

(E,E)-2,4-Decadienal

1781

5,9

7,6

9-ML00H

Methyl 8-oxooctanoate 1925

0,7

0,95

9-MLOOH

4,5

5,7

9-MLOOH

0,08

0,25

11

12 Methyl 9-oxononanoate 2010 13

Methyl 8-(2'-furyl) - 2097 octanoate

14 Methyl 10-oxo-(E)-8decenoate

2278

0,78

12-ML0ŒÎ 13-ML00H

11,4

1O-ML0OH

15

Methyl 11-oxo-9undecenoate

(1780)

0,8

2,8

1O-ML0OH 12-ML00H

16

Methyl 12-oxo-10dodecenoate

(1982)

0,2

0,9

12-MLOOH 13-ML00H

17 Methyl 13-oxo-(9 11)- (2175) tridecadienoate

1,2

2,6

13-ML00H

/

a)

Methyl linoleate solution was irradiated with light, presence of oxygen, without sensitizer (autoxidation)

b)

Methyl linoleate irradiated under same conditions, with methylene blue as sensitizer (photo-oxidation)

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

16.

TRESSL

ET AL.

Lipid Oxidation in Fruits and Vegetables

217

GC-system. The r e s u l t s o f t h e analogous p h o t o - o x i d a t i o n w i t h methylene b l u e as s e n s i t i z e r a r e p r e s e n t e d i n F i g u r e 2 and T a b l e I . D u r i n g t h i s r e a c t i o n oxygen i s t r a n s f o r m e d i n t o t h e s i n g l e t s t a t e , which may attack C = C ) . The ^C-ketol was reduced t o 9,10-dihydrcxy- ( E ) - 1 2 - o c t a d e c e n o i c a c i d . The components p r e s e n t e d i n F i g u r e 7 were s e p a r a t e d by HPLC and c h a r a c t e r i z e d by mass spectrometry, i n f r a r e d - and NMR-spectroscopy. The r e s u l t s w i l l be p u b l i s h e d i n d e t a i l ( T r e s s l and B a h r i , 1981) . The p u r i f i e d d i h y d r o x y a c i d was a l a b i l e compo­ nent and decomposed d u r i n g h e a t i n g i n t o c a r b o n y l s and o x o a c i d s . F i g u r e 8 p r e s e n t s some r e s u l t s o f t h e t h e r ­ mal f r a g m e n t a t i o n a t pH 4 - 5 i n a L i k e n s - N i c k e r s o n d i s t i l l a t i o n . I t c a n be seen t h a t we c h a r a c t e r i z e d c o n s t i t u e n t s s i m i l a r t o those i n the l i n o l e a t e e x p e r i ­ ment o f cucumber homogenates. 50 mg p r e c u r s o r (9,10d i h y d r o x y - ( Z ) - 1 , 2 - o c t a d e c e n o i c a c i d ) were decomposed i n t o : 1.95 mg (Z)-3-nonenal, 0.25 mg (E)-2-nonenal, 0.51 mg 2 - p e n t y l f u r a n , and C^-oxo- and C g - d i c a r b o x y l i c a c i d s . I n o u r o p i n i o n t h i s i s t h e most i m p o r t a n t r e a c t i o n i n o x i d i z e d beer ( p r o d u c i n g c a r d b o a r d f l a v o r ) . In an analogous r e a c t i o n l i n o l e n i c a c i d was t r a n s 2

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

226

QUALITY O F S E L E C T E D FRUITS A N D V E G E T A B L E S

/W V WW ©I =

=

I

0 0 H

00H

\ΛΛ=ΛΛΛΛΛ/

J

W

000Η

OH 0 0

wwyWvV " NaBfy

I

0

VV\=/YWVV

C00H

OH

Figure 7.

Synthesis of 9-hydroperoxy-(E,Z)-10,12-octadienoic acid

OH

vvwywwCOOH OH

ΝΛΛ-Λ

C H 0

ΛΛΛΛ OHC

V V V

COOH

CHO

(g?

-χ

HOOcW^OOH

@

COOH

Ο COOH

ΛΛΛΧ

J—] © cr o ^ -^ s

Figure 8.

A

19

v

Results of the thermal fragmentation at pH 4-5 in a Likens-Nickerson distillation

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

16.

TRESSL

ET AL.

Lipid Oxidation in Fruits and Vegetables

227

formed I n t o t h e c o r r e s p o n d i n g d i h y d r o x y a c i d . D u r i n g t h i s r e a c t i o n we observed the f o r m a t i o n o f p h e n o l s and a r o m a t i c hydrocarbons and some n o t i d e n t i f i e d p r o d u c t s . But 3,6-nonadienal and 2,6-nonadienal were formed as major components. V i c k and Zimmerman (2_6) demonstrated a f a t t y a c i d c y c l a s e i n c e r e a l s c a t a l i z i n g the c o n v e r ­ s i o n o f 13-LnOOH i n t o c y c l o p e n t e n o i c a c i d , which have s i m i l a r s t r u c t u r e s as p r o s t a g l a n d i n e s . F o r m a t i o n o f CQ- and Ci Q - (C-J ι ) -Components i n E d i b l e Mushrooms ( A g a r i c u s c a m p e s t r i s ) E d i b l e mushrooms l i k e A g a r i c u s b i s p o r u s (27) . Lent i n u s edodes S i n g (28) , B o l e t u s e d u l i s (29) produce 1 - o c t e n - 3 - o l 3 - o c t a n o l , 2 - o c t e n - l - o l , and 1-octen-3one as v o l a t i l e c o n s t i t u e n t s . 1 - 0 c t e n - 3 - o l p o s s e s s e s a mushroom-like arom hol". F r e y t a g and Ne from aroma c o n c e n t r a t e s and demonstrated a l a e v o r o t a t o r y form i n mushrooms. The r a c e m i c form i s known as a p r o d u c t from o x i d i z e d l i n o l e a t e i n c e r e a l s and vege­ t a b l e s . The o p t i c a l a c t i v i t y i n d i c a t e s a b i o s y n t h e t i c f o r m a t i o n o f ( - ) - 1 - o c t e n - 3 - o l i n mushrooms. Lumen e t a l . (1_7) demonstrated a l i p o x y g e n a s e - s y s t e m c a t a l i z i n g t h e c o n v e r s i o n o f l i n o l e i c a c i d i n t o 1 - o c t e n - 3 - o l . We i n v e s t i g a t e d the enzymic c o n v e r s i o n o f l i n o l e i c - , and l i n o l e n i c a c i d s i n t o Cs~ and C-|o-components by mush­ rooms. The methods used w i l l be p u b l i s h e d i n d e t a i l ( T r e s s l e t a l . , 1981). Some o f t h e r e s u l t s a r e sum­ m a r i z e d i n T a b l e V I . F r e s h mushrooms ( A g a r i c u s cam­ p e s t r i s ) were homogenized w i t h p h o s p h a t e b u f f e r a t pH 6.8 f o r 5 min and t h e v o l a t i l e s c o n c e n t r a t e d by d i s t i l ­ l a t i o n - e x t r a c t i o n . The v o l a t i l e s were i d e n t i f i e d and q u a n t i f i e d by c a p i l l a r y GC-mass s p e c t r o m e t r y . Major components : 1-Octen-3-ol, (Z) - 2 - o c t e n - 1 - o l , 3-octanone, and 1-octen-3-one. In an analogous experiment w i t h l i n o l e i c a c i d 1 - o c t e n - 3 - o l , 1-octen-3-one, (Z) -2o c t e n - 1 - o l , and (Z)-2-octenal increased considerably. In a d d i t i o n we c h a r a c t e r i z e d C-jo~components f o r the f i r s t time i n mushroom homogenates: f

10-Oxodecanoic a c i d 10-hydroxydecanoic a c i d 10-0xo-8-decenoic acid 1O-Hydroxy-8-decenoic a c i d 9-0xodecanoic a c i d 9-Hydroxydecanoic acid and two C-j 1 -components 10-0xoundecanoic a c i d 1O-Hydroxyundecanoic a c i d

3,4 32,6 1 ,93 0,76 0,3 0,5

ppm ppm ppm ppm ppm ppm

1 ,38 ppm 0,76 ppm

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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QUALITY OF S E L E C T E D

T a b l e VI

FRUITS A N D V E G E T A B L E S

F o r m a t i o n o f V o l a t i l e s i n Mushrooms (Agaricus campestris)

Ccmponent

Concentration I II Linoleic acid

(ppm) III Linolenic acid

Identification

1 Hexanal

+

+

+

MS

3-0ctanone

8,65

7,8

5,5

MS

4

3-0ctanol

1,5

2,0

1,25

5

1-Octen-3-one

0,7

2,2

1,1

6

1-0cten-3-ol

30,1

61,0

25,1

7

(Z ) -2-Octenal

1,8

7,5

1,9

8

(Z) -2-0cten-1-ol

4,8

17,4

5,0

9

(Z)-1,5-Octadien-3-one

+

+

0,33

10

(Z)-1,5-Octadien-3-ol

+

+

11

(Z,Z) -2,5-Octadienal

-

-

12

(Z,Z) -2,5-0ctadien-1 - o l

+

+

17,9

11,7

10,8

2

1-0ctanol

3

13 Benzaldehyde

15,8

27,5

+

I

Control experiment with fresh mushrocms

II

Addition of l i n o l e i c acid before homogenization

R f MS Rt, MS Rt, MS Rt, MS Rt> MS Rt/ MS, IR R f MS, IR R f MS R f MS, IR R f MS

III Addition of linolenic acid before homogenization

In Quality of Selected Fruits and Vegetables of North America; Teranishi, R., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 1981.

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TRESSL E T

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Lipid Oxidation in Fruits and Vegetables

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A l l oxo- and hydroxy a c i d s were c h a r a c t e r i z e d f o r the f i r s t time as enzymic d e g r a d a t i o n p r o d u c t s from l i n o l e i c a c i d . The major components 1 - o c t e n - 3 - o l and 1 , 5 - o c t a d i e n - 3 - o l were o p t i c a l l y a c t i v e . T h i s was proved by f o r m a t i o n o f an e s t e r w i t h an o p t i c a l l y a c ­ t i v e a c i d and c a p i l l a r y s e p a r a t i o n . The methods used w i l l be p u b l i s h e d i n the near f u t u r e ( T r e s s l and Engels 1981). These r e s u l t s i n d i c a t e a h i g h l y s p e c i f i c enzy­ me-system i n A g a r i c u s c a m p e s t r i s c a t a l y z i n g the con­ v e r s i o n o f l i n o l e i c a c i d i n t o ( - ) - 1 - o c t e n - 3 - o l and 10-hydroxydecanoic a c i d r e s p . i n t o (JZ) -2-octen-1 - o l and 9-hydroxydecanoic a c i d . As demonstrated i n T a b l e V I l i n o l e n i c a c i d i s t r a n s f o r m e d i n t o the c o r r e s p o n d i n g Cs-components c o n t a i n i n g two C = C