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ELEMENTS OF FOOD SCIENCE
By
Shafia Jan [NET, SLET Qualified] Assistant Professor Kashmir University Srinagar, Jammu & Kashmir
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Elements of Food Science
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) Ph.: 011-27341616, Fax: 011-27341717, Mob.: 09717133558 E-mail: info@nipabooks.com Web: www.nipabooks.com Š 2013, Author/Publisher 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. This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The author and publisher have attempted to trace and acknowledge the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission and acknowledgements to publish in this form have not been given. If any copyright material has not been acknowledged please write and let us know so we may rectify it. ISBN : 979-93-81450-24-6 Typeset at: Elegant Printographics # 98 91 24 73 05 Printed at: Jai Bharat Printing Press, Delhi
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Fundamentals of Veterinary Developmental Anatomy
DEDICATED
To My many Food Science & Dietetics students who made my teaching career such as pleasure & intellectual change
CONTENTS Dedication...........................................................................v Preface...............................................................................vi Chapter – 1: Sensory and Objective Evaluation of Foods .............................................................................. 1 Sensory evaluation of foods .......................................... 1 Objective evaluation of foods ....................................... 3 Factors affecting acceptability of foods ........................ 4 Sampling of food........................................................... 7 Selection of taste panel ................................................. 8 Types and methods of sensory evaluation of foods...... 10 Types and methods of objective evaluation ................ 12 Physical methods of food evaluation .......................... 13 Chemical methods of food evaluation ........................ 16 Study questions............................................................ 17 References ................................................................... 18 Chapter – 2 : Colloidal Chemistry................................. 19 Introduction................................................................. 19 Classification of colloids............................................. 21 Charge on colloidal particles....................................... 21 General structure of food stuffs .................................. 22 Relationship of cooking to colloidal chemistry .......... 28 Denaturation................................................................ 30 Browning of foods ...................................................... 31 Study questions............................................................ 36
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Elements of Food Science References ................................................................... 36
Chapter – 3 : Sugar Cookery ......................................... 37 Carbohydrates and Sugars........................................... 37 Commercial sugars...................................................... 39 Composition, nutritive value and place in diet ........... 41 Uses in food preparation ............................................. 42 Dietary sources of sugars ............................................ 43 Chemical reactions...................................................... 44 The Maillard reaction.................................................. 45 Crystallisation of sugar ............................................... 47 Factors affecting the size of crystals ........................... 48 Stages of sugar cookery .............................................. 50 Crystalline and non crystalline candies....................... 51 Study questions............................................................ 58 References ................................................................... 58 Chapter – 4 : Starch Cookery ........................................ 61 Starch .......................................................................... 61 Structure ...................................................................... 61 Amylose ...................................................................... 61 Amylopectin................................................................ 62 Types of starches......................................................... 63 Gelatinisation .............................................................. 67 Reterogradation........................................................... 68 Wheat .......................................................................... 69 Milling of wheat.......................................................... 69 Composition of wheat flour ........................................ 70 Gluten.......................................................................... 73 Baking quality of the flour .......................................... 75 Classification of flour mixtures................................... 77 Bread making .............................................................. 79 Leavening agents......................................................... 83 Gelatin ........................................................................ 91
Contents
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Composition ................................................................ 91 Properties .................................................................... 92 Preparation of Gelatin from collagen.......................... 95 Study questions............................................................ 96 References ................................................................... 96 Chapter – 5 : Milk Cookery ........................................... 97 Composition of milk ................................................... 98 Processing of milk..................................................... 101 Role of milk and milk products in cookery............... 105 Uses of milk in food preparation and different milk products.......................................................... 106 Properties of milk and its proteins ............................ 109 Manufacture of cheese .............................................. 111 Ice creams and frozen desserts.................................. 114 Principles of ice cream making................................. 115 Study questions.......................................................... 118 References ................................................................. 119 Chapter – 6 : Egg Cookery........................................... 121 Introduction............................................................... 121 Composition & nutritive value.................................. 123 Heat coagulation of egg proteins .............................. 124 Factors affecting coagulation .................................... 124 Uses of eggs in cookery ............................................ 126 Questions and activities ............................................ 129 References ................................................................. 130 Chapter – 7 : Vegetables and Fruits............................ 131 Introduction............................................................... 131 Structure of vegetable tissue ..................................... 132 Starch ........................................................................ 136 Pectic substances....................................................... 137 Pigments.................................................................... 139
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Elements of Food Science Enzymes .................................................................... 144 Study questions.......................................................... 145 References ................................................................. 145
Chapter – 8 : Fats and Oils .......................................... 147 Composition and nutritive value of fats.................... 147 Kinds of fats .............................................................. 148 Hydrogenated fats (Hydrogenation).......................... 151 Uses of fat and oil in food preparation...................... 152 Smoking points of fats .............................................. 156 Melting points of fats ................................................ 157 Changes in fat during cooking .................................. 158 Changes in fat during storage.................................... 159 Rancidity of fats and its types ................................... 159 Study questions.......................................................... 163 References ................................................................. 163 Chapter – 9 : Pulses and Legumes............................... 165 Introduction............................................................... 165 Composition and nutritive value ............................... 168 Factors affecting the cooking quality of legumes ..... 171 Germination of pulses ............................................... 174 Effect of germination on nutritive value of pulses.... 176 Study questions.......................................................... 177 References ................................................................. 177 Chapter – 10 : Fortification and Enrichment of Foods 179 Introduction............................................................... 179 Objectives.................................................................. 180 Commonly fortified foods and method of fortification 182 Study questions.......................................................... 188 References ................................................................. 189
Contents
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Chapter – 11 : Meat, Fish and Poultry........................ 191 Introduction............................................................... 191 Cuts and grades of meat ............................................ 195 Poultry....................................................................... 196 Grading of poultry..................................................... 197 Postmortem changes in muscle meat ........................ 200 Tenderness of meat ................................................... 202 Processing of Meat and its effects............................. 203 Processing of poultry and its effects ......................... 205 Fish Processing and its effect.................................... 207 Methods of cooking meat.......................................... 208 Cooking of poultry .................................................... 209 Cooking of fish.......................................................... 210 Study questions.......................................................... 210 References ................................................................. 211 Chapter – 12 : Food Adulteration ............................... 213 Introduction............................................................... 213 Common adulterants in different foods .................... 215 Prevention of food adulteration act........................... 218 Natural toxins present in food................................... 219 Effect of processing on nutritive value of foods ....... 220 Study questions.......................................................... 223 References ................................................................. 224
PREFACE
Food has never commanded more stories in the press or on television than it has in current decade. Public concerns about personal health and the environment have promoted the newsworthy nature of food. In particular, the merits of a healthy diet have been translated into emphasis on reducing the intake of fats & sugars while increasing the intake of fruits, vegetables and cereal products. The food industry has responded by developing many products to make it easier for consumers to follow dietary guidelines. Biotechnologists have been providing most of possible new directions to enhance the food supply. People in the media have added to the excitement, unfortunately not always with accurate message to consumers. The challenge is to keep moving toward a safe, adequate and pleasing supply of food that meets the true needs of consumers. This book provides a sound scientific knowledge in food science. It has been written to meet the needs of students in Indian Universities perusing courses in foods, nutrition and allied courses; at the undergraduate and postgraduate levels. The book covers all the necessary topics. The book gives a comprehensive account of foods. It consists of four parts. Part one, constituting (chapters 1-3), deals mainly with the evaluation of food, colloidal
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Elements of Food Science
chemistry of the food and sugar cookery. Starch, milk & egg cookery have been discussed in detail in part two (chapters (4 – 6). Part three (chapters 7 – 10) throws some light on vegetables, fats, pulses & fortification of foods; whereas the last part (chapter 11 - 12) deals with meat cookery and food adulteration. I trust that the book would be beneficial to all the students of dietetics & nutrition. Suggestions for improvements of the book are welcome. Shafia Jan
Fi r s tf e wp a g e so ft h i sb o o ka r ep u b l i s h e d o nk i s a n . c o mb yi t sp u b l i s h e r . I fy o uwi s ht op u r c h a s eah a r d c o p y o ft h i sb o o k , p l e a s ec o n t a c tt h ep u b l i s h e r .
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