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Oilseeds: Properties, Processing, Products and Procedures
 8190723758, 9788190723756

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OILSEEDS

OILSEEDS — Properties, Processing, Products and Procedures

G. NAGARAJ Principal Investigator Directorate of Oilseeds Research Rajendranagar, Hyderabad - 500 030 Andhra Pradesh, India

NIPA

2021

New India Publishing Agency Pitam Pura, New Delhi- 110 088

Published by Sumit Pal Jain for

New India Publishing Agency 101, Vikas Surya Plaza, CU Block, L.S.C. Mkt., Pitam Pura, New Delhi- 110 088, (India) Phone: 011-27341717, Fax: 011-27341616 E-mail: [email protected] Web: www.bookfactoryindia.com

© Author; 2021 The book has been supported by the Department of Science & Technology, Govt. of India, under its USERS Scheme. All rights reserved, no part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior written permission of the publisher / author. The views and ideas expressed in this volume are those of the authors alone. The authors and the publisher are not responsible for those views. Any information i.e. articles / materials / photographs / pictures / graphs / presentations etc. taken / adopted from any source (direct / indirect) would be the sole responsibility of the author alone.

ISBN : 978-81-90723-75-6

E-ISBN: 978-93-90083-30-5

Typeset at: Typographiya, Delhi Printed at: Jai Bharat Printing Press, Delhi Distributed by NIPA GENX Electronic Resources and Solutions Pvt. Ltd. New Delhi

v Dr. M. V. Rao, MLC Special Director-General, ICAR (Retd) Special Secretary, DARE, GOI (Retd) Vice Chancellor, ANGRAU (Retd) President, Agri Biotech Foundation Hyderabad

21, November, 2008

FOREWORD

I

ndia is one of the major oilseed producing countries occupying the fourth position in the world. The oilseed crops - both edible and non-edible and the cakes and other fractions from them play a crucial role in Indian economy, next only to the food crops. The edible oil crops supply essential nutrients in human and animal diets in terms of fats, proteins, carbohydrates and some essential minerals and vitamins. Vegetable oil sector is becoming more and more important in the Indian context because it has to meet the growing needs of humans, animals, industry and also the new emerging biofuel needs. The per capita consumption of edible oil is increasing with the change in the life styles and affluence of certain sectors of our population. The average per capita consumption which was only 4.5 kgs some years ago has risen to 11.5 kgs now and this is likely to rise further in future. Added to this is the ever growing population, which means India needs more and more oils and better nutritive oils in the years ahead. Oilseeds are also important constituents of animal feeds and organic manures, besides playing a vital role in industry for manufacture of paints, varnishes, lubricants and also for a whole range of consumer goods of daily use such as soaps, detergents etc. Since the country is not able to produce the needed quantities of edible oils it is resorting to heavy imports which is now touching more than 5 million tons costing Rs.10 to 12 thousand crores. Perhaps this is the highest amount spent by the Government on import of any agricultural commodity. The scenario is likely to get more complicated in the coming years because there will be less edible oil in the international markets and even if it is available it will be costier as a result of diversion of the oils for production of biofuels by the oil exporting countries. This is also leading to food shortages in the world. Hence India has to make every effort to increase the present oilseed production of 28 million tons to the projected demand of 60-70 million tons by 2020. India is fortunate to have all the agroclimatic conditions to grow a whole range of oilseed crops which no other country is capable of. Prominent oilseed crops raised in India are groundnut, soybean, rapeseed-mustard, sunflower, safflower, niger and sesame for edible purposes and non-edible castor and linseed for industrial and other uses. It also grows a number of oil bearing tree species like coconut, oil palm, sal, mahua,

vi kokum, melia, neem etc. To further increase domestic edible oil production rice and cotton seed are being exploited for producing rice bran oil and cotton seed oil. In recent years Jatropha, Pongamia, Simarouba glauca, Jojoba are being promoted as sources of biofuel. This biofuel sector is assuming great importance in view of the high prices of fossil fuels in which India is very deficient and also because of their biodegradable nature and less environmental problems. India occupies the second position in the world for area under groundnut, castor and rapeseed-mustard and coconut and fourth position for soybean and first position for linseed and sesame. India occupies the first position in the world for area under paddy and cotton. In terms of human resource and infrastructure development to develop manpower and laboratory and industrial capabilities the country showed remarkable and enviable vision. A number of institutions and industries are in position and also the strategies to further augment our efforts and facilities. The oil extracting and trading sectors are one of the biggest and most vibrant sectors, employing millions of people. India also exports certain quantities of oilseeds like groundnut, sesame, niger, castor, defatted soyflour and oil cakes of groundnut, mustard etc. In this context of oilseed scenario, any extra knowledge and information in terms of production, processing, product development and other related issues will be of great interest to scientists, technicians, policy makers, industry, farmers and students. The book by Dr G Nagaraj on “OILSEEDS — Properties, Processing, Products and Procedures” fills this gap and is very timely. The book covers all aspects of oilseed scenario involving major and minor oilseed crops, tree species and challenges, advances and progress in post harvest handling of the oilseeds and their products. It is very informative and comprehensive and I am sure all those people involved with oilseeds sector directly or indirectly, will be greatly benefited by this book. Dr Nagaraj has put in a lot of effort in writing this book and I congratulate him warmly for his effort. I am sure the book will be well received by all sectors of society interested in oilseeds and oil economy of India.

M.V. Rao

vii

PREFACE

O

ilseeds and their products have been playing an important role in our day to day lives since ages. They serve as sources of major and micro nutrients to humans and animals and help in their growth and health management. In this aspect they are better than cereal grains due to their better and balanced nutrient composition. As organic manures, again, they help in increased crop production. Various phytochemicals and oleochemicals are useful as medicines and cosmetics. Oils, proteins and their value added products have wide ranging industrial uses. They have recently gained importance as diesel substitutes. All these aspects with respect to the cultivated and other minor oleaginous sources have been presented and discussed in this book. Post harvest handling and processing to obtain good quality oilseed products and their utility also find a place. Antinutrients and their detoxification for better utilization of oilseed products have also been covered. Methods for evaluation of various quality parameters of oilseeds, oil and oil cakes are also included in the book. It is expected that this book will be useful to students, researchers and all those involved in oilseeds management. I am greatly indebted to Padmashri Dr. M.V. Rao, Dr. P.S. Reddy and Dr. M.K. Chakraborty who have encouraged me in my career as an oilseed scientist in the Indian Council of Agricultural Research. I sincerely thank the Department of Science and Technology, Ministry of Science & Technology, Government of India for the financial support under their USERS scheme to write this book. I acknowledge the infrastructural facilities provided to me at the Directorate of Oilseeds Research, Hyderabad. I also thank my wife and sons for their help and support while writing this book. This is a first major and single handed effort by me. I would greatly appreciate useful suggestions to improve the content and quality of this book in the later editions.

Hyderabad November, 2008

G. Nagaraj Ex. Head & P.S. Biochemistry 210, Ravathe Towers Maruthi Nagar, Kothapet Hyderabad - 500 060, India [email protected] [email protected]

ix

CONTENTS

Foreword Preface

v vii

Chapter 1 : Introduction _______________________

1

Chapter 2 : Cultivated Oilseeds _________________

7

Groundnut ............................................................................ 7 Rapeseed-Mustard ............................................................ 28 Safflower ............................................................................ 43 Sunflower ........................................................................... 58 Sesame .............................................................................. 70 Soybean ............................................................................. 85 Niger .................................................................................. 99 Castor .............................................................................. 109 Linseed ............................................................................ 123 References ....................................................................... 133

Chapter 3 : Tree Borne and Minor Oil Sources _____ Palm oil ............................................................................ 168 Rice Bran oil .................................................................... 178 Corn oil ............................................................................ 189 Cottonseed (Gossypium) oil ............................................. 195

167

x Coconut ............................................................................ 202 Olive ................................................................................. 209 Neem (Azadirachta indica) ............................................... 213 Jatropha ........................................................................... 223 Karanj (Pongamia glabra) ................................................ 230 Mahua (Madhuca) ............................................................ 236 Simarouba ........................................................................ 242 Kokum (Garcinia indica) ................................................... 248 Melia-The Bead tree ......................................................... 250 Sal (Shorea Robusta) ....................................................... 253 Rubber (Hevea braziliensis) ............................................. 260 Kusum (Schleichera trijuga) ............................................. 261 Crambe ............................................................................ 265 Mango (Mangifera indica) ................................................ 268 Moringa ............................................................................ 273 Tumba .............................................................................. 277 Tobacco seed oil............................................................... 279 Jojoba (Simmondsia Chinensis) ...................................... 283 References ....................................................................... 288

Chapter 4 : Processing________________________ Post Harvest Technology .................................................. 301 Oil extraction .................................................................... 314 Ghani extraction ............................................................... 315 Oil expeller ....................................................................... 317 Solvent extraction ............................................................ 323 Extrusion expeller ............................................................ 326 Super critical fluid extraction ............................................ 328 Palm oil production .......................................................... 331 Refining of oil ................................................................... 336 References ....................................................................... 346

301

xi

Chapter 5 : Oilseed Products ___________________

349

Nutritional quality of edible oils .......................................... 349 Keeping quality of oils ....................................................... 359 Hydrogenated fats ............................................................ 363 Shortenings ...................................................................... 365 Margarines ....................................................................... 367 Oilseed extractions ........................................................... 370 Oilseed based food products ............................................ 377 Oleo-chemicals ................................................................. 398 References ....................................................................... 410

Chapter 6 : Antinutrients_______________________

419

Antinutrients ..................................................................... 419 Ricin-the toxic protein ...................................................... 429 Mycotoxins ....................................................................... 438 Glucosinolates ................................................................. 450 References ....................................................................... 456

Chapter 7 : Procedures _______________________ Methods of analysis ......................................................... 465 Fats, oils and lipids .......................................................... 466 Extraction and purification of lipids ................................... 467 Chromatographic purification of lipids .............................. 468 Oil analysis by soxhlet extraction ..................................... 469 Oil content (cold percolation method) ............................... 471 Oil content (NMR method) ................................................ 472 Oil and moisture contents by pulsed NMR ....................... 473 Specific gravity/ density of fats and oils ............................ 476 Colour of the oil ................................................................ 477 Determination of free fatty acids ....................................... 477 Free fatty acids - colorimetric method ............................... 479 Refractive index ............................................................... 480 Saponification value ........................................................ 481

465

xii Unsaponifiable matter ....................................................... 482 Iodine value....................................................................... 484 Iodine value by dam’s reagent ........................................... 485 Peroxide value (PV) .......................................................... 486 Fatty acid methyl esters (FAME)........................................ 488 Fatty acid composition by gas chromatography ................. 491 Lipid profile studies .......................................................... 495 Determination of lipase activity.......................................... 497 Phospho Lipids ................................................................. 498 Estimation of crude proteins.............................................. 499 Protein and total N by micro-kjeldahl method ..................... 501 Protein content .................................................................. 503 Protein by biuret reaction .................................................. 505 Protein by ultraviolet absorption ........................................ 506 Free amino acids .............................................................. 507 Protein digestibility (in vitro) .............................................. 508 Total carbohydrates (phenol: sulphuric acid method) .......... 509 Total water soluble sugars (T.S.S.) ..................................... 511 Total reducing sugars ........................................................ 513 Sugars (alkaline ferricyacide – colorimetric method) ......... 514 Determination of total and reducing sugars ....................... 515 Determination of crude fibre .............................................. 517 Estimation of cellulose ...................................................... 518 Starch - method-I ............................................................... 519 Starch - method-II .............................................................. 521 Antinutritional factors ......................................................... 522 Chlorogenic acid (HPLC method) ..................................... 524 Estimation of oxalic acid ................................................... 525 Estimation of phytic acid ................................................... 526 Estimation of polyphenols ................................................. 527 Estimation of tannins ......................................................... 528 Aflatoxins by thin layer chromatography (TLC) ................... 529 Aflatoxins by elisa ............................................................. 533

xiii Aflatoxins by HPLC method .............................................. 535 Crude ricin ........................................................................ 538 Ricin: RID assay ............................................................... 540 Ricin: HPLC method ......................................................... 541 TLC of sugars (raffinose, stachyose and verbacose) ......... 541 Glucosinolates-quick test for the determination of glucosinolates ............................................................... 543 Gluco test method for glucosinolates ................................. 544 Glucosinolates-desulphation and HPLC ............................ 546 Analysis of sesame lignans ............................................... 548 Vitamin A (HPLC method) ................................................. 549 Vitamin A (spectrophotometric method) ............................. 551 Beta carotene ................................................................... 552 Thiamine (vitamin B1) ....................................................... 553 Tocopherols (HPLC method) ............................................. 554 Total tocopherols-colorimetric method ............................... 555 Gross calorific value (GCV) ............................................... 557 Carbon and hydrogen content ........................................... 559 Mineral analysis ash content.............................................. 562 Atomic absorption spectrophotometry ............................... 564 Calcium (titrimetric method) .............................................. 566 Calcium (colorimetric method) .......................................... 567 Phosphorus (fiske and subba row method)........................ 568 Iron (wong’s method) ......................................................... 570 Potassium (flame photometric method) ............................. 570 References ....................................................................... 571

Appendix ________________________________

575

Index____________________________________

591

1

Chapter

Introduction H

uman being as a hunter has depended mostly on animal food and some fruits. With the progress of civilization, he settled down and started agriculture around 7000-10,000 B.C. He started depending on plant grains to take care of his energy and nutritional requirements in addition to animal foods. Initially cereal grains must have mostly accounted for his staple food requirements. Taste and health requirements must have prompted him to diversify his crop production programme. It is this need that must have made him to cultivate oilseeds, fibre and other crops. Oilseeds, thus, have been under cultivation since antiquity. Rapeseed and sesame have been described in the Indian Sanskrit writings of 2000 BC. Historically, extraction of oil seems to have been a batch process. Seeds kept in gunny bags or boxes were pressed to remove oil. The separated oil on clarification was used for food and non food purposes. The resulting cakes were utilized as animal feed or thrown away into fields which helped in improving the soil fertility. Human beings slowly discovered the uses of oil and other oilseed products for various food and non-food purposes. There are several species of plants in the world whose oil can be utilized for human consumption. Though around 40 oilseeds are known, only around a dozen oilseed crops have become commercially important. There are ten seed crops and three tree crops. The seed crops are groundnut, rapeseedmustard, sesame, soybean, sunflower, cottonseed, safflower, niger, castor and - 1-

2

Oilseeds

linseed. These are mostly annual crops. The three major tree oil crops are palm, olive and coconut. Among the cultivated annual oilseed crops soybean accounts for about 62% of the total world oilseed production. As a vegetable oil source, it may not be the leader due to its lower oil content of around 18%. It is followed by rapeseed-mustard and groundnut with about 13-14% of the total oilseed production. Sunflower occupies the fourth place with about 9% of world oilseed production. These four oilseeds together account for 98% of the cultivated world oilseed production. Castor, sesame and linseed account for the remaining 2%. Cottonseed is also an important edible vegetable oil source. The seed as well as oil are by products of the textile industry. Similarly niger is a valuable edible oil source cultivated in some countries. The total world cultivated oilseed production stood at around 360 million tonnes in the year 2006. This was produced from an area of 180 million ha, at a productivity level of around 2000 kg/ha. World Area, Production and Productivity of Oilseeds During 2006 Oilseed

Area X 1000 ha

Production X 1000 tonnes

Groundnut

22232

47768

13.41

2149

Rapeseed & Mustard

28474

49466

13.8

1737

Soybean Sesame

92989 7539

22150 3338

61.9 0.9

2382 443

Sunflower

23700

31332

8.7

1322

822

583

0.1

709

Linseed

3017

2570

0.7

852

Castor

1264

1140

0.3

902

180037

357699

100

1987

Safflower

Total

% of total Yield kg/ha production

Among the perennial oil sources, palm oil, in recent years has gained lot of prominence. It has almost become the major vegetable oil of the world being utilized for various food and non-food purposes. This is mainly because of higher oil yield from this tree. The production of palm oil averages around 40 million tonnes annually. The yield of oil from palm trees can be as high as 8 tonnes /ha. Coconut is another multipurpose oil source grown in the coastal regions of the tropics. The dried copra is the richest source of oil containing upto 65% oil. The annual availability of coconut oil varies around 3.3 million tonnes. The third tree oil source, olive, accounts for 1.6 million tonnes of world

Introduction

3

vegetable oil production. This crop is confined to the Mediterranean region of the globe. Past few decades saw the emergence of hither to unknown sources of oil. Large scale requirement and local shortages have prompted the identification of many new sources. They are ricebran, corn, sal, mahua, jatropha, kokum, melia, rubber, mango kernel, kusum, simarouba, neem, karanj, crambe, moringa, tumba, jojoba and tobacco seed etc. Most of these oilseeds and their products have wide utility in the specialty oils sector and are mostly used for nonedible purposes. Soaps and detergents along with paint and varnish industry are the major consumers of these non-traditional oilseeds. They also serve as high value and eco-friendly lubricants. Some non-traditional oilseeds and their products have pesticidal and medicinal uses. They are also much sought after raw material by the cosmetic industry. Vegetable oils, in recent years, are gaining importance as diesel fuel due to depleting mineral oil reserves. Oilseeds will gain greater attention in future as they are renewable and biodegradable in nature. Non-traditional oilseeds like jatropha and karanj are expected to play an important role as raw material for the production of biodiesel. Oilseeds apart from being sources of oil have a lot of importance as nutritious food items. Oilseeds like soybean, groundnut and sesame are utilized as food and in the preparation of various value added and nutritious food products. They even have neutraceutical value. Components of the oilseeds like oil, protein, carbohydrates, minerals, vitamins and trace constituents have wide and varied uses. The major constituents, oil, protein and sugars have a role in calorie nutrition of the human beings. Animal products have some negative impact on health. Animal fats increase the blood cholesterol levels and cause obesity. Hence their use is under scrutiny. Though animal protein is more balanced in amino acid composition, it is costly and is not available to a major chunck of the population. Ethical considerations and cruelty against animals also go against the use of animal products. It is in this background that vegetable sources are gaining importance as nutritional sources. Cereal crops account for a major portion of our food. However, they are richer in one major component of food, namely, starch and hence are imbalanced with respect to nutrition. Oilseeds are next in importance and are more energetic and nutritious than cereal grains. They contain most of the food components like carbohydrates, proteins, oils, minerals, vitamins, essential fatty acids (EFA) and essential amino acids (EAA) and other nutrients. The oilseeds are generally richer in oils/fats ranging from 20-55%. The other major components are proteins and sugars ranging from

4

Oilseeds

20-30% each. Minerals, vitamins and other micro- nutrients account for around 5- 10% of the seeds. Oilseeds have a lot of economic importance as sources of oil, protein and other food and non-food constituents. Human beings need to consume 20% each of their nutritional energy through oils and proteins. Oilseeds supply both these constituents along with carbohydrates, minerals, EFA, EAA and vitamins required by the human body. They add taste to other foods. Some oilseeds like groundnut, sesame, sunflower kernels and niger are widely utilized in various food preparations. These oilseeds are directly edible and can be eaten with minimal processing. They have lot of snack food value all over the world. Soybean, though highly nutritious, needs processing prior to it’s utilization as a food item. Many products of soybean are marketed world wide. Some oilseeds like rapeseed, linseed and safflower are consumed as food items in limited quantities in specific locations. The presence of antinutrients and or non-palatability etc. hinder their utilization. Lot of progress has been made to reduce or detoxify the antinutrients present in the oilseeds. Oilseeds like castor are unique with respect to their utility. Castor serves as the source of one of the best natural lubricant especially for the aviation industry. Most non-edible oilseeds are utilized by the industry in the manufacture of various value added products like soaps, detergents, paints, varnishes, cosmetics, lubricants, pesticides etc. With improvements in standard of living along with mechanization and automation taking place world over, the demand for vegetable oils will increase, year after year. Search for new seeds with natural and engineered composition to suit specific applications will continue. Genetic engineering will play a major role in the years to come in catering to the world food and oil supplies. Oilseeds and their derivatives constitute a significant part of global business. Around 300 millions tones of oilseeds are produced globally every year. 90-100 million tonnes of oil get traded all over the world. Around 150160 million tonnes of oil meals mostly as by products of oil extraction industry are also available. In monetary terms the business relating to oilseeds and their products add upto around $ 110 billion. Oilseeds and their products vary greatly in their chemical composition and quality. The season and the location under which they are grown as well as genotypes have an effect on the composition and quality of the oilseeds. Post-harvest technology and processing of oilseeds also have great influence on the quality of oilseeds and their products. Understanding the quality and

Introduction

5

its evaluation are also important to all the stake holders, namely, the producer, processor, policy makers and the consumers. This book is written keeping in view all these aspects. The chapters that follow deal with the cultivated oilseeds, tree borne and minor oilseeds, post harvest technology, processing, products and their utility. The last chapter deals with methods of oilseed quality evaluation. Efforts have been made to include most of the known oilseeds. Information on the seed, oil and the protein qualities have been presented. Mineral, vitamin and other micro-nutrient compositions have also been included. Food and non-food products along with antinutrients find a place. This book should cater to the needs of students, researchers, producers, technologists and planners.

2

Chapter

Cultivated Oilseeds Groundnut

G

roundnut is believed to have originated in Brazil and later spread to many countries all over the world. It is known to humanity since 950BC. Groundnut crop and its products have multiple uses. Being a leguminous crop it enriches the soil with nitrogen through symbiotic biological fixation by rizhobium. The economic product, groundnut in shell, contains the seeds, which are edible. The shell as well as the haulms serve as fuel and fodder. The seed oil serves as a good cooking oil while the cakes are good sources of protein for animals and even humans. Groundnut (Arachis hypogaea L,) belongs to leguminosae family and papilionacea sub family. It consists of two sub species each with two varieties. The first one hypogaea has the variety hypogaea (virginia group) and variety hirsuta kohla while the second one fastigiata has the variety fastigiata (valencia group ) and the variety vulgaris (spanish group). Hypogaea varieties are spreading types with branching and lack infloresence on the main stem. They are of longer duration and have fresh seed dormancy . Varieties of the fastigiata are of erect type with branching and flowering on the main stem also. The crop is of shorter duration than hypogaea types, but with little fresh seed dermancy. The major groundnut producing countries of the world are China, India, Nigeria, U.S.A. Indonesia, Argentina, Sudan, Senegal and Myanmar. The - 7-

8

Oilseeds

cultivation is spread in tropical and sub-ropical regions. Groundnut is a selfpollinated crop and pollination takes place in the morning. After fertilization an elongated stalk namely peg develops which enters the soil, bends horizontally and swells to become a pod. Within the pod, two, three or four kernels are formed. The crop can be grown under rainfall conditions ranging from 50-125cm, with good distribution during flowering and pegging stages. Sandy loams, loamy soils, and black soils with good drainage are suitable for growing the crop. Groundnut is raised mostly as a rainfed kharif crop, being sown from May to July, depending upon the monsoon rains in India. In the rabi season, groundnut is sown in the southern states during November-December, mostly in the rice fallows. Summer groundnut is sown during the second fortnight of January upto the first fortnight of February. To control seed borne diseases, seeds should be treated with Thiram or Mancozeb (3g/kg of kernel) or Carbendazim (2g/kg). Normally about 120 kg seeds/ha for bunch and 100110 kg seeds/ha for semi-spreading and spreading varieties are adequate. The spacings are 30x10cm or 45x10cm or 30x15cm for different groundnut types. For irrigated groundnut, the recommended spacings are 22.5x10 cm or 30x7.5cm. Groundnut needs more phosphorus, sulphur and calcium. Seed inoculation with efficient strains of rhizobium can partially meet the nitrogen requirement of the crop. FYM or compost, 10-15 t/ha should be applied well before sowing and should be incorporated into the soil. NPK at 20:50:20 kg/ ha is also applied before sowing. The erect types can be harvested in 110-125 days, while the spreading types are harvested in 140-160 days. The bunch and semi-spreading varieties are usually harvested by hand-pulling when there is adequate moisture in the soil. The spreading types, on the other hand, are harvested by digging with a spade, or by ploughing or working a blade harrow. The pulled-out plants are stacked for a few days for drying and the pods are stripped afterwards. In bunch types, the pods are stripped by hand from the dry plants. In case of runner types, the plants are allowed to dry and then beaten with sticks or fed to a thresher to separate the pods from vines. The stripped pods are cleaned and dried to a safe moisture content of around 5%. It is desirable to store groundnuts in gunny bags as pods rather than as kernels. Higher humidity favours fungal growth. When A.flavus infects the groudnuts, it poses health problems due to prodution of aflatoxins. Hence proper storage is the most important aspect in groundnuts.

Cultivated Oilseeds

9

Groundnut Shell and Seed Groundnuts as they are produced have an outer thick woody shell. Inside it are normally embedded 2 or 3 kernels. The seed (65 to 75 % of the pod) consists of two cotyledons and a germ with an outer thick brown skin called testa. The colour of the testa varies from red, brown, purple to white depending on the type and variety. Cotyledons constitute the bulk of the kernel ranging from 92 to 94%, and the testa and germ account for 3-4% each of the seed weight. The chemical composition of these different parts of the seed are presented in Table 1. The testa is rich in carbohydrates and crude fibre with little or no oil. The germ is rich in oil (39-43%) and proteins (26-28%). The cotyledons are also rich in oil (36-54%) and proteins (21-36%). The cotyledons also contain higher levels of carbohydrates (6-24%). Both the germ and cotyledons contain very low levels of crude fibre (