FOOD AND NUTRITION: School Edition

292 Pages·1997·19.791 MB·English

by  Anita Tull

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Oxford Llniversitv Press
STOURBRIDGE COLLEGE
Oxford University Press, Great Clarendon Street, Oxford 0X2 6DP
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Oxford is a trade mark of Oxford University Press Acknowledgements
© Oxford University Press 1996 The publishers toould like to thank the following for permission
First published 1983 to reproduce their photographs:
Second edition 1987
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Third edition 1996
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Reprinted 1997
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!0!A‘iS. No
Pie chart on p. 74 reproduced by permission of The
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UV. Food Magazine, published by the Food Commission.
\o;^n Aj 'r I II i Graphs on pp. 148 & 149 from Social Trends 25, 1995,
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Preface
This book is designed to provide a The book is divided into five chapters. At the
comprehensive text for students working end of each section within a chapter there are
towards GCSE examinations in food and short revision questions, arranged in order of
nutrition. It will also be a valuable resource for difficulty, for use in class or for private study.
students on GCSE courses in food technology, Each chapter ends with a series of more
and on related GNVQ courses. structured questions and activities that require
The text has been fully revised to include the investigation and individual or group study. The
latest dietary guidelines, up-to-date information clearly illustrated, full colour text also includes
on diet and health, and current legislation on the experimental work to form a link between the
safe supply of food. The impact of food practical and theoretical aspects of food science.
technology on choice and availability of food is
covered, and a new chapter looks at providing
food for different needs. Scientific aspects of the
subject are emphasized so that students can
understand the value of food, and the principles
behind its production, storage, preparation, and
use. Practical food preparation, hygiene and
safety, kitchen equipment, and consumer
protection are also covered.
Contents
1 Nutrition 3 Foods and food science
Diet and health 1 Food production, processing.
The nutrients 2 and retail 77
Protein 2 Cereals 85
Fat 5 Fats and oils 91
Carbohydrate 9 Sugar and sweeteners 97
Food tests 11 Milk 99
Vitamins 12 Cream ■ 105
Fat-soluble vitamins 12 Cheese 106
Water-soluble vitamins 16 Yogurt 109
Mineral elements 21 Eggs 112
Water 26 Meat 116
Dietary fibre (NSP) 26 Fish 126
Energy 28 Alternative protein foods 129
Digestion and absorption 33 Gelatine 131
The nutrient content of foods 36 Vegetables 132
Dietary guidelines 38 Pulses and nuts 136
Nutritional labelling 40 Fruits 137
Choice of food 41 Herbs 140
Nutritional disorders related to food Spices 141
shortages 43 Food additives 142
Health disorders related to unwise Convenience foods 144
food choice 44 Fast food 147
Questions and activities 50 Food packaging 147
Questions and activities 148
2 Providing food for different needs
4 Practical food preparation
Meal planning 53
Following dietary guidelines 54 Principles behind the cooking
Pregnant women 55 of food 150
Infancy 57 Food spoilage 154
Toddlers and young children 59 Preservation of food 163
School-age children 60 Home preservation of fruit 171
Adolescents 60 Choosing, preparing, and
Adults 61 cooking food 175
People living on low incomes 64 Methods of cooking 176
Senior citizens 65 Moist methods of cooking 176
illness and convalescence 66 Dry methods of cooking 183
Vegetarians 68 Frying 187
Religious groups 70 Microwave cookery 190
Food intolerance 71 Freezer cookery 195
Questions and activities 74 Use of left-over foods 203
Raising agents 204
Cakes 208
Yeast mixtures 212
Batters 215
Sauces 216
Salads 218
Soups and stocks 220
Summary of changes in food
during preparation 221
Summary of changes in food during
cooking 223
Food presentation 224
Food preparation for assignments,
investigations, and examinations 229
Commercial restaurants 232
Questions and activities 233
5 The kitchen
Kitchen planning 235
Materials used in the home 244
Cookers 247
Refrigerators 253
Kitchen equipment 255
Consumer protection 263
Kitchen safety 266
Questions and activities 272
Weights 277
Liquid measures 277
Qven temperatures 277
Index 278
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Diet and health
Food is vital to life. It can be defined as any solid so are of use to the body in several ways. Some
or liquid substance which, when taken by the foods, such as sugar, contain only one nutrient,
body, provides it with the necessary materials to and are of limited use to the body. However, no
enable it to grow, to replace worn-out and single food provides all the nutrients required by
damaged parts, and to function normally. the body in sufficient quantities, so a variety of
The human body is like a complex piece of foods must be eaten.
machinery in that it is prone to faults and The terms used in the study of nutrition
weaknesses it if is poorly maintained. This can include the following.
happen if too little or too much food is eaten, or Diet means the food that a person normally eats
if the daily food intake is in any way unbalanced. every day. There are also special diets, e.g.
One way of ensuring that health and fitness slimming diets, low-fat diets.
are maintained, when food is plentiful, is to have
Malnutrition means an incorrect or
an understanding of food and its effects on the
unbalanced intake of nutrients.
body and to use this knowledge wisely.
Under-nutrition means an insufficient total
What is nutrition?
intake of nutrients.
Food, like other substances, is composed of
Balanced diet means a diet that provides the
different chemical elements, arranged in a
correct amount of nutrients for the needs of an
variety of ways to form molecules. These
individual.
molecules collectively give individual foods their
flavour, colour, and texture, and affect their
Metabolism
reaction to heat and their digestion.
The human body is a complex living structure
The body uses some of the molecules in food
composed of millions of individual units called
to function correctly and to stay healthy. These
cells. Cells are grouped into systems containing
are the nutrients. There are many different
various tissues and organs, each performing
nutrients, and each has its own function in the
special functions.
body. Each nutrient is vital to hfe, and the health
Within the body, chemical reactions and
of an individual will suffer if any one nutrient is
changes are continually taking place. These
in short supply.
enable the body to carry out all the necessary
The study of nutrients and their relationship
functions and processes, as well as to grow and to
with food and living things is called nutrition.
replace damaged and worn-out body cells. This
Most foods contain more than one nutrient.
1
Chapter 1 • Nutrition
complex collection of chemical reactions is Two particular DRVs are important:
called metabolism. estimated average requirement (EAR) and
Energy is required for all metabolic reference nutrient intake (RNI).
reactions, and the body must remain healthy if it The RNI is the amount of a nutrient required to
is to be efficient. This is mainly achieved by the meet the daily needs of 97% of each group in the
intake of nutrients in food. Humans, like all population. In this book, we use RNIs.
living things, must have a regular supply. People who are ill, undernourished, or have a
particular medical condition may have different
needs for certain nutrients.
For energy requirements an average figure is
The nutrients
given because people vary greatly in how much
energy they .use every day. If the figure was set
There are five main groups of nutrients:
too high some people would become obese if
protein
they were to eat food with the recommended
fat
energy value each day.
carbohydrate
vitamins
minerals
Protein
Each group has several members, which each
have their own chemical names.
Macronutrients are needed by the body in Functions
relatively large amounts. They include protein,
Our bodies are composed of millions of cells
fat, carbohydrate, and the mineral elements
which are constantly being replaced and
sodium, calcium, potassium, phosphorus, and
repaired. As the body grows, new cells are
magnesium.
added.
Micronutrients are needed by the body in
Each cell contains a substance called
smaller amounts. They include vitamins,
protoplasm, which contains (amongst other
essential fatty acids, and trace elements (the
things) protein. Protein is vital for the growth,
minerals iron, zinc, copper, iodine, selenium,
repair, and maintenance of the body.
chromium, and cobalt).
Protein can also be used to provide the body
Water can also be called a nutrient, as it is
with energy, once it has been used for its main
vital to life.
functions of growth and repair.
Some foods contain dietary fibre or non¬
Chemistry
starch polysaccharide (NSP), which is not
strictly a nutrient, but is still of importance to There are many different pi'oteins and they are
the body. It will be discussed separately. all complex molecules which contain these
elements:
Dietary reference values
oxygen (O) carbon (C)
The Department of Health has compiled charts
hydrogen (H) nitrogen (N)
showing people’s requirements for energy and
and sometimes:
nutrients. The figures in the charts are given the
sulphur (S) phosphorus (P)
general name dietary reference values (DRVs).
The protein molecules are made up of small
People’s need for nutrients varies throughout
units joined together like links in a chain.
their life. For example, the needs of a 5-year-old
These units are called amino-acids.
boy are different from those of a pregnant
At least 22 different amino-acids are known
woman. DRVs are therefore given for particular
to occur naturally, and each has its own chemical
groups of the population. They are not meant to
name. Different proteins are made when
be specific targets for individuals.
different numbers and types of amino-acids
2