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Food Commodities
1
CONTENTS
1.
2.
3.
4.
5.
6.
7.
8.
What are Food Commodities
Rice, Wheat and Cereals
Meat & Poultry
Seafood
Eggs
Cheese & Milk
Legumes, Vegetables and Fruit
Summary
1. What are food commodities?
Products or raw materials that can be bought or
sold.
They are:
wheat, rice & cereals
meat & poultry
seafood
eggs
cheese & milk
legumes, vegetables & fruit
2. WHEAT, RICE &
CEREALS
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2. WHEAT, RICE & CEREALS
Wheat
• Main cereal food in many Western
countries.
• Grown in regions such as USA,
Canada, Europe, Russia, Egypt and
India.
2. WHEAT, RICE & CEREALS
Structure of
Wheat
• Composed of 3 parts:
– Bran
– Endosperm
– Germ
Source: http://www.pechsiam.com/allabout.htm, 2006
2. WHEAT, RICE & CEREALS
Types of Flour
Types
Soft, weak flour, low in protein
Hard, strong flour, high in protein
(made from hard red winter wheat)
Hard, strong flour, high in protein
(made from hard red spring wheat)
White wheat flour
(made from hard white wheat)
Uses
For making cookies, cakes, crackers & pastries
For making pan breads, pizza crusts & rolls
Mainly for making breads
For making the same products as soft & hard red wheat
Durum flour
(made from durum wheat)
• course ground endosperm (semolina) – for production
of pastas
• durum flour – for making American noodles & some
types of pastas
Wholegrain & wholemeal flour
For making breads & muffins
2. WHEAT, RICE & CEREALS
Nutrients in Wheat
•
•
•
•
•
Carbohydrates
Proteins
Fats
B-vitamins
Vitamin E
•
•
•
•
Iron
Phosphorus
Calcium
Fibre
2. WHEAT, RICE & CEREALS
Using Wheat in Cooking
• When heat is applied in a baked product, the
proteins coagulate to give final structure of the
product.
• The starch granules absorb water, swell & burst,
resulting in a moist product.
• Commonly used as the main ingredient for cakes,
biscuits, pastries, bread & snack items.
2. WHEAT, RICE & CEREALS
Rice
• Staple food in several Asian countries,
particularly China, India, Japan & Korea.
• Structure is similar to wheat.
• Can be short-grained (glutinous when cooked)
or long-grained (fluffy when cooked)
2. WHEAT, RICE & CEREALS
Types of Rice
 Polished rice
 Unpolished rice
 Glutinous rice
2. WHEAT, RICE & CEREALS
Nutrients in Rice
•
•
•
•
Carbohydrates
Proteins
Fats
B-vitamins
• Iron
• Phosphorus
• Magnesium
2. WHEAT, RICE & CEREALS
Using Rice in Cooking
• When cooked in water, the grains absorb water &
swell.
– If correct amount of water is used : light, fluffy & glutinous rice is
produced
– If too much water is used : rice turns mushy
• Consumed as cooked plain rice or made into rice
products such as dumplings, porridge, rice crispes
or longtong.
2. WHEAT, RICE & CEREALS
Cereals
• Seed grains of cultivated
grasses.
• Most common staple food
in most countries as they
are relatively inexpensive
& easy to grow.
2. WHEAT, RICE & CEREALS
Types of Cereals
Types
Nutrients
Uses
Maize (corn)
• Carbohydrates, proteins, fats,
fibre, iron and vitamins especially
B1, B2 & B3
• Yellow variety contains carotene
that can be converted into vitamin
A by the body
• Eaten as ‘corn-on-the-cob’
• Used in soups & cereals
• Crushed corn grain – for making tortilla
• Fine corn flour – thickening agent for
gravies & soups
• Used in cakes, biscuits & blancmange
Oat
Higher fat, protein & soluble dietary
fibre content than other cereals
For making oat porridge, muesli & oat
brans
Barley
Similar to other cereals
• Used in barley drinks, soups and local
desserts
• Added to cattle feed & used in the
whisky-making industry
Rye
Similar to other cereals
For making breads, biscuits & pancakes
3. Meat & Poultry
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3. MEAT & POULTRY
Meat
• Refers to the flesh of animals, which is made
up of muscles & fats.
• Animals are reared on farms for their meat.
3. MEAT & POULTRY
Types of Meat
•
•
•
•
•
Beef (from cattle)
Mutton (from goat & sheep)
Pork (from pig)
Veal (from calf)
Venison (from deer)
3. MEAT & POULTRY
Structure of Meat
• Composed of 2 main proteins:
– Myosin
– Actin
– Click here to find out how myosin and actin look like.
• Fibres are held together in bundles by connective
tissue, which is made up if 2 proteins :
– Collagen
– Elastin
• Small amount of fats in between muscle fibre of
lean meat are known as marbling fats – contributes
to flavour, moisture & texture.
3. MEAT & POULTRY
Structure of Meat
Legend
Actin
Myosin
Back
Source: http://www.exploratorium.edu/cooking/meat/INT-what-is-meat.html, 2006
3. MEAT & POULTRY
Nutrients in Meat
•
•
•
•
•
Proteins
• Phosphorus
Fats
• Sulphur
Cholesterol
• Iron
Vitamin D
• Water
Vitamins, especially B1, B2 & B3
3. MEAT & POULTRY
Using Meat in Cooking
• When cooked using dry heat such as roasting,
soluble proteins coagulate resulting in some
shrinkage.
• Colour of meat changes from red to brown.
• During moist-heat cooking such as braising,
insoluble proteins are slowly converted into soluble
gelatine. Soluble vitamins & minerals are passed
into cooking water. Some flavouring matter leave
the meat, making the meat less tasty.
3. MEAT & POULTRY
Before cooking
Beef muscle fibers with
blow-up of a coiled
protein, before cooking
After cooking
An uncoiled, or
denatured, protein, after
cooking
Source:http://www.exploratorium.edu/cooking/meat/INT-what-is-meat.html, 2006
3. MEAT & POULTRY
Poultry
• Domesticated birds such as:
–
–
–
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Chickens
Ducks
Geese
Turkeys
3. MEAT & POULTRY
Nutrients in Poultry
•
•
•
•
Proteins
Fats
Cholesterol
Vitamin B-group
• Phosphorus
• Iron
• Water
3. MEAT & POULTRY
Using Poultry in Cooking
• Method of cooking depends on age of the bird.
• Young bird is tender & has very little fat – best fried,
grilled or roasted whole.
• Over-roasting tends to toughen the meat & make
the flesh dry.
• Older bird is tougher as it has more connective
tissue in the muscles – suitable for simmering,
boiling & steaming.
• Can be used to make stews, soups, pies & burgers.
3. MEAT & POULTRY
Offal
• Edible internal parts of
the animals such as:
–
–
–
–
–
–
–
Liver
Heart
Kidneys
Tripe (stomach)
Tongue
Brain
Intestines
Source: http://www.halalmeat.com.au/offal.html, 2006
3. MEAT & POULTRY
Nutrients in Offal
• Proteins (high)
• Fats
• Cholesterol (high)
3. MEAT & POULTRY
Using Offal in Cooking
• Requires thorough cleaning to remove
any unpleasant smell.
• Liver & kidneys are best sliced thinly &
fried.
• Tripe & intestines are usually boiled or
made into a stew.
4. Seafood
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4. SEAFOOD
Seafood
• Comprises:
– Fish
– Shellfish
4. SEAFOOD
Types of Fish
• White fish
– Pomfret
– Red snapper
– Threadfin
• Oily fish
– Mackerel
– Shad
4. SEAFOOD
Types of Shellfish
• Crustaceans
– Crabs
– Prawns
– Lobsters
• Molluscs
–Cockles
–Clams
–Oysters
4. SEAFOOD
Structure of Seafood
• Has less connective tissue than meat &
no elastin.
• Muscle fibres are shorter than those of
meat – easier to cook & more digestible
than meat.
• Shellfish is tougher & more chewy –
less digestible than white & oily fish.
4. SEAFOOD
Nutrients in Seafood
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•
•
•
•
•
•
• Potassium
Proteins
• Sodium
Cholesterol
Calcium
• Phosphorus
Iron
• Water
Iodine
Unsaturated fats (little or no)
Vitamin A, D & B-group
4. SEAFOOD
Using Seafood in Cooking
• In dry-heat cooking such as frying, soluble proteins coagulate,
causing shrinkages. As water evaporated from the surface of
the seafood, deposits of flavouring matter & minerals are left
behind – makes fried fish & prawns tasty.
•
In moist-heat cooking such as boiling, water-soluble nutrients
& flavouring matter may be lost from the seafood – seafood
may taste bland.
• Fish can be grilled, baked, pan-fried or steamed.
• Used as fish curry, fried fish, fish cakes and fishballs. Raw fish
(sashimi) is a Japanese delicacy.
• Shellfish can be fried, frilled, steamed or boiled. Molluscs must
be properly cooked as they tend to harbour harmful bacteria.
5. Eggs
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5. EGGS
Eggs
• Economical food source that can be used in
a variety of ways.
• One of the most common breakfast foods.
5. EGGS
Types of Eggs
• Eggs of:
– Chicken
– Ducks
– Geese
– quails
5. EGGS
Structure of Eggs
• Composed of 3 main parts:
– Eggshell
– Egg white
– Egg yolk
5. EGGS
Source:
http://www.eggs.ab.ca/about/egggrades.htm,
2006
5. EGGS
Nutrients in Eggs
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•
•
•
•
•
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Proteins
• Sodium
Fats
• Chlorine
Cholesterol
• Sulphur
Calcium
•
Water
Iron
Potassium
Vitamin A, B-group, D, E & K
5. EGGS
Using Eggs in Cooking
• Heat causes proteins to coagulate
– egg white turns solid & opaque
– egg yolk turns solid, dry and powdery
• Can be fried, boiled, scrambled, poached,
steamed or made into omelettes, soufflés &
custards.
EGGS
Using Eggs in Cooking
• Have the following uses in cooking:
–
–
–
–
–
–
–
As a main protein food such as omelette
For thickening soups, sauces, puddings & custards
As a rising agent in cake-making
For trapping air to make food light. Eg: chiffon cakes
As an emulsifier. Eg: mayonnaise
For glazing pastries & pies to give them a shiny look
For coating food. Eg: fish cutlets
6. Cheese & Milk
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6. CHEESE & MILK
Milk
• Usually obtained from cows.
• Milk of other animals such as goats & mares
is also consumed by people.
• Milk & its products such as butter, cream &
cheese are known as dairy foods.
6. CHEESE & MILK
Types of Milk
Types
Properties
Untreated mlik
Milk that has not gone through any kind of heat
treatment; bottled in the farm
Pasteurised milk
Milk that has been given mild heat treatment (72°C
for 15 secs) to destroy most disease-carrying germs
Homogenised milk
Pasteurised milk processed to disperse the fat
globules & distribute them evenly throughout the
milk
Sterilised milk
Homogenised milk heated to a high temperature
(113°C for 15-40 min) in a vacuum-sealed container
Ultra-high temperature milk
(UHT milk)
Homogenised milk heated to a high temperature of
132°C for not more than 1 sec; packaged in sealed
cartons; can be kept for months without refrigeration
6. CHEESE & MILK
Types of Milk
Types
Properties
Evaporated milk
Milk from which some water has been removed by
evaporation; contains 25% less water than fresh milk;
sterilised at 115.5°C for 20 min
Condensed milk
Milk from which some water has been removed by
evaporation; sweetened with sugar
Powdered milk
Milk from which all water has been removed; in
powder form
Skimmed milk
Milk with fats skimmed off
6. CHEESE & MILK
Nutrients in Milk
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•
•
•
•
•
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Carbohydrates
• Sodium
Proteins
• Chlorine
Fats
• Phosphorus
Cholesterol
•
Water
Calcium
Potassium
Vitamin A, B1, B2, B3, C & D
6. CHEESE & MILK
Using Milk in Cooking
• When milk is boiled, proteins coagulate & form a layer on the
surface. As the boiling continues, hot air & steam get trapped
under this layer – causes the milk to overflow from its container.
• Can be consumed on its own.
• Used in beverages such as tea, coffee, cocoa & milkshake.
• Used in many parts of the world to make desserts.
• Also processed to produce dairy products such as cheese, cream
& butter.
6. CHEESE & MILK
Cheese
• Concentrated form of milk
• A means of preserving the nutritive value of
milk – most important milk product
6. CHEESE & MILK
Types of Cheese
• Very hard cheese
• Soft cheese
– Cream cheese
– Parmesan cheese
– Processed cheese
• Hard cheese
– Cottage cheese
– Cheddar cheese
6. CHEESE & MILK
Nutrients in Cheese
•
•
•
•
•
•
• Sodium
Proteins
• Chlorine
Fats
• Phosphorus
Cholesterol
• Water
Calcium
Potassium
Vitamin A, B1, B2, B3, C & D
6. CHEESE & MILK
Using Cheese in Cooking
• When cheese is heated, the fat melts & separates, &
the cheese becomes soft.
• On further heating, the proteins over-coagulate &
become stringy & tough.
• Used in macaroni & cheese, cheese biscuits,
cheesecake, cheese scones & cheese sauce.
• Also used as topping for food items like pizza, lasagne
and salads.
7. Legumes,
Vegetables & Fruit
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7. LEGUMES, VEGETABLES & FRUIT
Legumes & Pulses
• Plants with seeds that grow in special fruits
known as pods
• Legumes – pods
• Pulses – edible dried seeds within the pods
7. LEGUMES, VEGETABLES & FRUIT
Types of Legumes & Pulses
• Legumes
– French beans
– Long beans
• Pulses
– Peas
– Lentils
– Peanuts
7. LEGUMES, VEGETABLES & FRUIT
Nutrients in Legumes & Pulses
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•
•
•
•
Carbohydrates
Proteins
Fats
Fibre
Vitamin B-group
• Iron
• Calcium
• Potassium
7. LEGUMES, VEGETABLES & FRUIT
Using Legumes & Pulses in Cooking
• Pulses need to be soaked in water prior to
cooking – causes them to swell & soften –>
easier to cook, usually by boiling or simmering.
• Used in soups, stews, salads & dhal curries.
• Used to make tofu, soya milk, tempeh, soya
sauce & salted soya beans.
• Textured soya protein is known as textured
vegetable protein.
7. LEGUMES, VEGETABLES & FRUIT
Vegetables
• Plants or plant parts that are
used as food
7. LEGUMES, VEGETABLES & FRUIT
Types of Vegetables
Types
Examples
Nutrients
Leaves
Lettuce, spinach,
cabbage, kale, mustard
greens
Vitamin A, C, E & K, calcium,
iron, sulphur, phosphorus
Stems
Celery, asparagus
Vitamin A, B1, B2, B6, folic
acid, potassium
Tubers
Potato, sweet potato,
yam, tapioca, water
chestnut
Carbohydrates, vitamin C
Roots
Carrot, turnip
Carbohydrates, vitamin A, B6
& C, calcium
7. LEGUMES, VEGETABLES & FRUIT
Types of Vegetables
Types
Examples
Nutrients
Onion, garlic
Carbohydrates, vitamin A, B6
& C, calcium
Flowers
Cauliflower, broccoli
Vitamin A, B-group, C & E,
folic acid, potassium,
phosphorus, magnesium
Fruits
Tomato, cucumber,
eggplant
Vitamin A, B-group & C,
potassium
Bulbs
7. LEGUMES, VEGETABLES & FRUIT
Using Vegetables in Cooking
• Vegetables are cooked to make them more digestible.
• During cooking, volume of vegetables is reduced as the fibres are
soften. Heat also causes starch grains to swell & gelatinise.
• When green vegetables are cooked, they initially appear to
become greener due to chlorophyll pigments. Upon long period of
cooking, the pigments break downs to appear yellowish.
• Leafy vegetables may be stir fried or boiled & eaten with the
liquid.
• Root vegetables may be baked, roasted, braised or pressuredcooked.
• Soft vegetables such as tomatoes & fresh mushrooms may be
grilled.
7. LEGUMES, VEGETABLES & FRUIT
Fruit
• Prized for its refreshing flavour & sweetness
• Most fruit, when ripe, can be eaten at any time
or after a meal as a dessert.
• Others are better after they are cooked.
7. LEGUMES, VEGETABLES & FRUIT
Types of Fruit
Types
Examples
Stone fruit
Peach, cherry, plum, apricot
Fleshy fruit
Apple, pear, pineapple, papaya, banana, melon
Berry fruit
Strawberry, blackcurrant, raspberry, gooseberry
Citrus fruit
Orange, lemon, tangerine, lime
Dried fruit
Sultana, raisin, date, prune, currant
7. LEGUMES, VEGETABLES & FRUIT
Nutrients in Fruit
•
•
•
•
•
• Potassium
Carbohydrates
• Phosphorus
Fibre
• Manganese
Calcium
• Water
Iron
Vitamin A, B-group & C
7. LEGUMES, VEGETABLES & FRUIT
Using Fruit in Cooking
• Fruit is usually eaten raw, either on its own or in salads.
• May also be cooked by stewing, baking, frying & boiling.
• Can be used in pie fillings, pies, puddings, fritters & jams.
May be chopped or pureed before use.
• During cooking, pectin in acidic fruit dissolves in the warm
acid condition, softening the tissues. Cellulose walls are
also softened. Soluble nutrients are found in the liquid,
which should be eaten with the fruit.
• Boiling inactivates the enzymes in the fruit, preventing it
from turning brown.
8. Summary
•
•
•
•
By the end of this lesson, you should be able to:
Understand the features of different types of
foods
List the nutritive composition of the various
foods: cereals, meat, fish, eggs, dairy products,
pulses, legumes, vegetables and fruit.
Choose food commodities wisely.
Explain how food are used in cooking and their
chemical changes.