FOOD COMMODITIES
NTD 201 (3 UNITS)
Course requirements:
CAT: 30% Exam: 70%
Class attendance compulsory
*Contact Lecturer ahead of time if any cogent reason will keep you away from lectures.
Present medical reports if absence from lectures/CAT was due to ill health.
Sanni, S. A. , PhDDepartment of Nutrition & Dietetics
University of AgricultureAbeokuta
SynopsisFood ClassificationMarket SurveysFood Selection & purchasingUses of FoodsFoods and Food tablesCereals, Starches & starchy foods, Sugars, Pulses, nut and seedsVegetables and fruitMeat, fish etc.Infective agents in foodNatural food toxins
Food DefinedFood is any substance that is consumed to
provide nutritional support for the body, possibly to the point of excess.
It is usually of plant or animal origin, and contains essential nutrients, such as carbohydrates, fats, proteins, vitamins, or minerals.
The substance is ingested by an organism and assimilated by the organism's cells in an effort to produce energy, maintain life, and/or stimulate growth.
Food Classification
Food Selection & purchasing The types of food you select depends on: the money you have your nutritional needs and the effect of advertisements Now let us examine each of these factors and see how they influence our selection
or choice of food! Nutritional needs Your food choice will also depend on your need for food. Everyone has a biological
need for food. It is essential for life without food one becomes weak and ill. People vary in the amount of food they need for reasons like health, age and activity.
Your choice of food will therefore depend on each of these factors. Your nutrition knowledge helps you to choose food that provides the necessary nutrients to meet your needs.
Food Purchasing Food purchasing can be a boring or interesting adventure depending on one’s
approach to it. To make food purchasing interesting you have to know much about the market place and ways in which you can make the most out of your food budget.
Now let us look at some of the things you can do to avoid waste of your time and money when purchasing food.
First of all you need to know the factors that determine the cost of the things you want to purchase.
Foods and Food tables-------------------Carbohydrates------------------- Fats Proteids
Foods Rich in
Mineral SaltsChocolate Honey Vegetables - Butter Cheese Vegetables -
Fruits - Nuts - Asparagus Cheese Eggs Asparagus
Dates Chestnuts Bananas Chocolate Fish Beet-tops
Figs Peanuts Beets Cream Legumes - Cabbage
Grapes Pignolia or Cabbage Nuts - Beans - dried Carrots
Persimmons pine nuts Carrots Almonds Lentils - dried . Celery
Raisins Sirups Celery Brazil-nuts Peas - dried Dandelion
Grains - Sugar Lettuce Cocoanuts Milk Green peas
Barley Tapioca Onions Hickory- Nuts - Lettuce
Corn Parsnips nuts Peanuts Onions
Oats Potatoes - Peanuts Pignolia or Radish-tops
Rice sweet Pecans pine nuts Romaine
Rye Potatoes - Pignolia or Poultry Spinach
Wheat white pine nuts Vegetables - String beans
Pumpkin Walnuts Cabbage Turnip-tops
Spinach Oils - Lettuce Watercress
Squash Cottonseed Onions Wheat bran
Turnips Nut-oil Spinach
Olive-oil Turnips
Wheat bran
CEREALS
Cereals are the edible seeds or grains of the grass
family.
There are many different types of cereal grains, each
having unique properties.
Most cereals are processed to form other foods or
ingredients. Cereals and cereal products are an
important source of energy, carbohydrate, protein
and fibre. They also contain a range of
micronutrients such as vitamin E, some of the B
vitamins, sodium, magnesium and zinc. Wheat and
rice are the most important cereal crops world-wide
as they account for over 50% of the world’s cereal
production.
TYPES OF CEREALS
Wheat: is usually ground to flour which is used to produce a
wide range of products. The type of flour produced differs
according to the rate of extraction. Couscous and cracked
wheat or bulgur is also made from wheat. Wheat can be
fermented to make beer.
Maize: (or corn) may be processed to make many different
ingredients (e.g. high fructose corn syrup which can be used as
an alternative to sucrose derived from sugar cane and sugar
beet) and food products. It may be milled in a similar process to
wheat. Its germ is rich in oil, and can be refined to produce
corn oil.
Barley: is mainly sold as pearl barley, which is the whole grain
with its husk removed. It is also used in bread (as flour) and
ground as porridge in some countries.
Rice: brown rice has its outer husk removed, and white rice is
milled and polished further to remove the bran and germ. There
are many different types of rice, categorized by size, shape and
the region where they are grown. Rice can be ground to make
flour and is used to make Japanese rice wine (saké).
Rye: contains little gluten, so produces breads with low volume
and a dense texture, although in Russia, Poland, Germany and
Scandinavian countries it is the major bread grain. Rye is also
used to produce crisp bread and alcohol.
Oats: are rolled rather than crushed during processing.
Coarse, medium and fine grades of oatmeal are available and
are used for porridge and oatcakes, while rolled oats are used
for porridge, and oat flour is used for baby foods and for ready-
to-eat (RTE) breakfast cereals.
Millet: is the name used for a number of different small-
grained cereal grasses, e.g. pearl, finger (or ragi), proso and
foxtail millet. These crops are important in parts of Africa and
Asia.
Sorghum: (also known as great millet, guinea corn, kafir corn,
jowar and kaoling in different parts of the world) is a staple
food in many parts of Africa, Asia and parts of the Middle East.
It is also used as animal feed in many other countries.
NUTRITIONAL VALUE OF CEREALS AND CEREAL PRODUCTS
Cereals and cereal products are an important source of energy,
carbohydrate, protein and fibre.
They also contain a range of micronutrients such as vitamin E, some of
the B vitamins, sodium, magnesium and zinc. Because of the
fortification of some cereal products they also contribute significant
amounts of calcium and iron.
There is evidence to suggest that regular consumption of cereals,
specifically whole grains, may have a role in the prevention of chronic
diseases. The strength of evidence varies and although cause and
effect has not currently been established, people who consume diets
rich in whole grain cereals seem to have a lower incidence of many
chronic diseases, e.g. coronary heart disease and type 2 diabetes.
It remains to be established whether this is a direct effect, or whether
whole grain consumption is merely a marker of a healthy lifestyle or
some other factor.
Structure of the maize kernel (caryopsis)
Essential Amino Acid Content of Cereal ProteinsEssential Amino Acids
Percentage content
Rice Corn Wheat
Arginine 8.40 9.36 24.06
Histidine 2.60 0.75 7.89
Isoleucine 4.50 0.80 0.00
Leucine 8.40 31.22 33.91
Lysine 3.50 6.71 5.88
Methionine 2.50 2.35 4.84
Phenylalanine 4.50 9.34 8.40
Threonine 3.90 2.90 2.00
Tryptophan 1.20 2.07 8.14
Valine 6.50 1.88 3.85
ROOTS AND TUBERS
Roots are plant materials which edible portions grows under the soil
but the stem serve as planting materials, while tubers are thick parts
or swollen parts of an underground stem bearing small buds from
which new plants can be formed. Roots and tubers belong to the class
of foods that basically provide energy in the human diet in the form of
carbohydrates. The principal root and tuber crops of the tropics are
cassava (Manihot esculenta Crantz), yam (Dioscorea spp.), sweet
potato (Ipomoea batatas L.), potato (Solanum spp.) and edible aroids
(Colocasia spp. and Xanthosoma sagittifolium). They are widely grown
and consumed as subsistence staples in many parts of Africa, Latin
America, the Pacific Islands and Asia. The increased use of major roots
and tubers – cassava, potato, sweet potato, and yam, for food and
livestock feed in developing countries will have wide-ranging effects on
global public- and private-sector policies and investments. Roots and
tubers will continue to play a significant role in developing-country
food systems because they:
a. contribute to the energy and nutrition requirements of
more than 2 billion people;
b. are produced and consumed by many of the world’s
poorest households;
c. are an important source of employment and income in
rural, and often marginal, areas, especially for women,
and
d. d.adapt to a wide range of uses, from food-security crops
to cash crops, raw material for industrial uses, and from
fresh to high-end processed products.
Roots and tubers together constitute a significant share of the
total volume and value of horticultural crops worldwide. These
commodities are particularly important as a source of food,
employment, and income in developing countries where the
bulk of the world's producers, processors, and consumers
reside. In this new millennium, roots and tubers will play
Cereals and oil seeds Roots and tubers
1.Low moisture content, typically 10% to 15%
High moisture content, typically 70% to 80%
2. Small unit size, typically less than 1 gram
Large unit size, typically 100 grams to 15 kg
3. Very low respiration rate with very low generation of heat. Heat production is typically 0.05 megajoule/ton/day for dry grain
High respiration rate. Heat production is typically 0.5 to 10 megajoules/ton/day at 0°C to 5 to 70 megajoules/ton/day at 20ºC
4. Hard texture Soft texture, easily bruised
5. Stable, natural shelf life is several years
Perishable, natural shelf life is a few days to few months
6. Losses usually caused by moulds, insects and rodents
Losses usually caused by rotting (bacteria and fungi), senescence, sprouting and bruising
Chemical Composition of some Tropical Roots and TubersCommodity
Dry Crude Ether Total Energy Ascorbic Calcium Phosphorus Fe Matters Protein extract ash acid (g) (g) (g) (g) (cals) (mg) (mg) (mg) (mg)
Cassava
31.94
2.71 0.53 2.66 390.0 35.0 10.0 35.0 0.50
Yam 26.17
5.87 0.46 4.30 385.9 17.0 18.9 40.7 0.48
Cocoyam(Taro)
26.52
8.66 0.71 4.83 376.4 14.0 24.0 53.6 0.72
Cocoyam(Tannia)
24.89
7.85 0.70 5.22 382.6 10.0 6.0 360.0 0.70
Sweet Potato
28.08
5.36 0.33 3.15 391.0 26.2 16.6 31.0 0.83
Pulses (Legumes)Legumes are widely distributed world- wide and generally referred to as pulses. Every zone of
the world has some legumes peculiar to them.
For example, in France, groundnuts are found, in South America, lima and runner beans, in the United States, soya beans and in Africa, cowpeas, bambara nut, broad beans, in India, lentils and chick peas etc.
The fruit is a pod containing seeds ranging generally from 2-10 seeds. There are two main types of legumes, viz :
I. Those containing high protein and high oil content.
II. Those containing moderate protein and low oil content.
Examples of the first group include soya bean, groundnut, lupin and winged beans. The protein content is as high as 35% while oil content vary from 15 - 45%.
Examples of the second group include cowpea, gram, pea, bambara groundnut, lentil and the different varieties of the phaseolus group. The protein content is in the range of 25- 30% while the oil content is less than 5%.
Legumes are generally high in B vitamins but low in sulphur containing amino acids, methionine and cystine. They have high content of lysine which makes legumes a good complement to cereals (cereals are low in lysine but high in methionine).
Legumes have some nutritional disadvantages apart from being deficient in methionine and cystine. These are of low digestibility and the consumption of high proportion of legumes in the diet can cause flatulence. Some legumes contain toxic substances which interfere with normal enzymic reactions.
Composition of some LegumesLegumes Moisture Energy Protein Fat Total
(g) (KJ) (g) (g) Carbohydrates(g)
Bambara groundnut
10 1550 20 6 60
Black eye Beans(raw)
13 1360 23 1.5 58
(Decorticated) 30 1080 20 1.2 44
(Moi- moi) 70 500 7 2 20
(Akara) 60 920 9 15 14
Black gram (Urad dahl)
10 1450 24 1.5 60
Chick pea (Bengal gram)
11 1360 20 5.6 60
Humous (Chick pea paste)
60 770 8 13 11
Groundnut (Dry) 5 2570 26 48 20
Lentil (Masar dahl
12 1300 20 0.6 65
Lima (Butter) Bean
12 1162 20 1.5 58
Mung Bean 12 980 22 1.0 35
(Sprouts) 90 146 3.8 0.2 6
Pea 78 280 5.8 0.4 11
Soya Bean 10 1700 40 20 20
Winged Bean 10 1700 33 17 37
Composition of some FruitsCommodity
Water(%)
Energy(cal)
Protein (%)
Fat(%)
Carbohydrate (%)
Ascorbic acid (%)
Calcium (%)
Phosphorus (mg)
Vit. A (i.u)
Fruits
Banana
75 86 1.1 0.2 24 10 8 26 190
Pineapple
85 65 0.4 0.4 15 110 20 11 30
Mango
83 63 0.6 0.1 15 30 10 10 180
Guava 80 58 1.0 0.4 13 200 15 33 200
Orange
86 49 1.0 0.2 12 50 41 20 200
Lemon
85 58 1.0 0.9 11 43 40 22 -
Cashew apple
85 - 0.7 - 13 250 10 - 150
Pawpaw-ripe
81 40 0.5 0.6 10 110 16 8 2200
Commodity
Water(%)
Energy(cal)
Protein (%)
Fat(%)
Carbohydrate (%)
Ascorbic acid (%)
Calcium (%)
Phosphorus (mg)
Vit. A (i.u)
Onions
89 38 1.5 0.1 9 10 27 56 40
Carrot 88 42 1.1 0.2 10 51 37 36 11000
Spinach
91 26 3.2 0.3 5 51 93 51 8100
Cabbage
92 24 1.3 0.2 4 47 49 29 130
Pepper
92 22 1.2 0.2 4 125 9 22 420
Tomato
93 22 1.1 0.2 5 30 13 27 190
Composition of some Vegetables
Composition of Meat and Meat ProductsType % Composition of Edible Portion
Water Protein Fat Ash Carbohydrate
Beef (medium fat) 60.0 17.5 22.0 0.9 -
Veal (medium fat) 66.0 18.8 14.0 1.0 -
Pork (medium fat) 42.0 11.9 45.0 0.6 -
Lamb (medium fat)
56.0 15.7 27.7 0.8 -
Chicken 66.0 20.2 12.6 1.0 -
Duck 52.8 16.2 30.0 1.0 -
Turkey 58.3 20.1 20.2 1.0 -
Fish (fillet non fat) 81.8 16.4 0.5 1.3 -
Fatty fish fillet 68.8 20.0 10.0 1.4 -
Crustaceans 79.3 14.6 1.7 1.8 2.6
Dried fish 4.0 60.0 21.0 15.0 -
Milk (cow) 87.3 3.5 3.5 0.7 5.0
Cheese (hard) 37.0 25.0 31.0 5.0 2.0
% Composition of Raw Fish FleshLean Fatty
Water 80 60-80
Protein 16-18 16-18
Lipids 0.5-2.0 5-20
Extractives(salts glycogen, amino acids
0.5-2.0 0.5-2.0
Mineral content 1.0-1.5 1.0-1.5
Lean: cod, haddock, whiting, rockfish, sole
Fatty: Salmon, mackerel, trout, butterfish
Infective and Toxic Agents in FoodsThere are more than 200 known diseases that
can be transmitted through food, however, and the known causes of food poisoning include infective agents and toxic agents.
Infective agents include viruses, bacteria, and parasites.
Toxic agents include poisonous mushrooms, improperly prepared exotic foods (such as barracuda), or pesticides on fruits and vegetables.
Sources of Food ContaminationFood usually becomes contaminated with
these agents from poor sanitation or preparation. Food handlers who do not wash their hands after using the bathroom or have infections themselves often cause contamination.
Improperly packaged food stored at the wrong temperature also promotes contamination.
Three of the most important causes of food poisoning are the salmonella, clostridium botulinum and staphylococcal organisms.
Further ReadingsCollingham, E. M. The Taste of War: World War
Two and the Battle for Food (2011)Marion Nestle: Food Politics: How the Food
Industry Influences Nutrition and Health, University Presses of California, revised and expanded edition 2007, ISBN 0520254031
Katz, Solomon. The Encyclopedia of Food and Culture, (Scribner, 2003)
http://en.wikipedia.org/wiki/Foodhttp://www.healthscout.com/ency/68/676/
main.html