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Food Commodities

CONTENTS

1. What are Food Commodities2. Rice, Wheat and Cereals3. Meat & Poultry4. Seafood5. Eggs6. Cheese & Milk7. Legumes, Vegetables and Fruit8. Summary

They are:wheat, rice & cerealsmeat & poultryseafoodeggscheese & milklegumes, vegetables & fruit

1. What are food commodities?

Products or raw materials that can be bought or sold.

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2. WHEAT, RICE & CEREALS

• Main cereal food in many Western countries.

• Grown in regions such as USA, Canada, Europe, Russia, Egypt and India.

2. WHEAT, RICE & CEREALS

Wheat

Structure of Wheat

• Composed of 3 parts:– Bran– Endosperm– Germ

2. WHEAT, RICE & CEREALS

Source: http://www.pechsiam.com/allabout.htm, 2006

Types of Flour

Types UsesSoft, weak flour, low in protein For making cookies, cakes, crackers & pastries

Hard, strong flour, high in protein(made from hard red winter wheat)

For making pan breads, pizza crusts & rolls

Hard, strong flour, high in protein(made from hard red spring wheat)

Mainly for making breads

White wheat flour(made from hard white wheat)

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

• Carbohydrates

• Proteins

• Fats

• B-vitamins

• Vitamin E

Nutrients in Wheat

• Iron

• Phosphorus

• Calcium

• Fibre

2. WHEAT, RICE & CEREALS

• 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.

Using Wheat in Cooking

2. WHEAT, RICE & CEREALS

• 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)

Rice

2. WHEAT, RICE & CEREALS

Polished rice

Types of Rice2. WHEAT, RICE & CEREALS

Unpolished rice

Glutinous rice

• Carbohydrates

• Proteins

• Fats

• B-vitamins

Nutrients in Rice

• Iron

• Phosphorus

• Magnesium

2. WHEAT, RICE & CEREALS

• 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.

Using Rice in Cooking

2. WHEAT, RICE & CEREALS

• Seed grains of cultivated grasses.

• Most common staple food in most countries as they are relatively inexpensive & easy to grow.

Cereals

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

OatHigher 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

2. WHEAT, RICE & CEREALS

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3. Meat & Poultry

• Refers to the flesh of animals, which is made up of muscles & fats.

• Animals are reared on farms for their meat.

3. MEAT & POULTRY

Meat

• Beef (from cattle)

• Mutton (from goat & sheep)

• Pork (from pig)

• Veal (from calf)

• Venison (from deer)

Types of Meat

3. MEAT & POULTRY

• 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.

Structure of Meat

3. MEAT & POULTRY

3. MEAT & POULTRY

Legend

Myosin

Actin

Source: http://www.exploratorium.edu/cooking/meat/INT-what-is-meat.html, 2006

Structure of Meat

Back

• Proteins

• Fats

• Cholesterol

• Vitamin D

• Vitamins, especially B1, B2 & B3

Nutrients in Meat

• Phosphorus

• Sulphur

• Iron

• Water

3. MEAT & POULTRY

• 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.

Using Meat in Cooking

3. MEAT & POULTRY

3. MEAT & POULTRYBefore cooking After cooking

Source:http://www.exploratorium.edu/cooking/meat/INT-what-is-meat.html, 2006

Beef muscle fibers with blow-up of a coiled

protein, before cooking

An uncoiled, or denatured, protein, after

cooking

• Domesticated birds such as:– Chickens– Ducks– Geese– Turkeys

Poultry

3. MEAT & POULTRY

• Proteins

• Fats

• Cholesterol

• Vitamin B-group

Nutrients in Poultry

• Phosphorus

• Iron

• Water

3. MEAT & POULTRY

• 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.

Using Poultry in Cooking

3. MEAT & POULTRY

• Edible internal parts of the animals such as:– Liver– Heart– Kidneys– Tripe (stomach)– Tongue– Brain– Intestines

Offal

3. MEAT & POULTRY

Source: http://www.halalmeat.com.au/offal.html, 2006

• Proteins (high)

• Fats

• Cholesterol (high)

Nutrients in Offal

3. MEAT & POULTRY

• 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.

Using Offal in Cooking

3. MEAT & POULTRY

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4. Seafood

• Comprises:

– Fish

– Shellfish

Seafood

4. SEAFOOD

• White fish– Pomfret

– Red snapper

– Threadfin

Types of Fish

• Oily fish– Mackerel– Shad

4. SEAFOOD

• Crustaceans– Crabs

– Prawns

– Lobsters

Types of Shellfish

• Molluscs–Cockles–Clams–Oysters

4. 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.

Structure of Seafood

4. SEAFOOD

• Proteins • Cholesterol• Calcium• Iron• Iodine• Unsaturated fats (little or no)• Vitamin A, D & B-group

Nutrients in Seafood

• Potassium• Sodium• Phosphorus• Water

4. SEAFOOD

• 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.

Using Seafood in Cooking

4. SEAFOOD

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5. Eggs

• Economical food source that can be used in a variety of ways.

• One of the most common breakfast foods.

5. EGGS

Eggs

• Eggs of:– Chicken

– Ducks

– Geese

– quails

Types of Eggs

5. EGGS

Structure of Eggs

• Composed of 3 main parts:– Eggshell– Egg white– Egg yolk

5. EGGS

5. EGGS

Source:http://www.eggs.ab.ca/about/egggrades.htm, 2006

• Proteins • Fats• Cholesterol• Calcium• Iron • Potassium• Vitamin A, B-group, D, E & K

Nutrients in Eggs

• Sodium

• Chlorine

• Sulphur

• Water

5. EGGS

• 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.

Using Eggs in Cooking

5. EGGS

• 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

Using Eggs in Cooking

EGGS

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6. Cheese & 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.

Milk

6. CHEESE & MILK

Types of Milk

Types Properties

Untreated mlikMilk that has not gone through any kind of heat treatment; bottled in the farm

Pasteurised milkMilk that has been given mild heat treatment (72°C for 15 secs) to destroy most disease-carrying germs

Homogenised milkPasteurised 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 milkMilk 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 milkMilk from which some water has been removed by evaporation; sweetened with sugar

Powdered milkMilk from which all water has been removed; in powder form

Skimmed milk Milk with fats skimmed off

6. CHEESE & MILK

• Carbohydrates• Proteins • Fats• Cholesterol• Calcium• Potassium• Vitamin A, B1, B2, B3, C & D

Nutrients in Milk

• Sodium

• Chlorine

• Phosphorus

• Water

6. CHEESE & MILK

• 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.

Using Milk in Cooking

6. CHEESE & MILK

• Concentrated form of milk

• A means of preserving the nutritive value of milk – most important milk product

Cheese

6. CHEESE & MILK

• Very hard cheese– Parmesan cheese

• Hard cheese– Cheddar cheese

Types of Cheese

• Soft cheese – Cream cheese– Processed cheese– Cottage cheese

6. CHEESE & MILK

• Proteins

• Fats

• Cholesterol

• Calcium

• Potassium

• Vitamin A, B1, B2, B3, C & D

Nutrients in Cheese

• Sodium

• Chlorine

• Phosphorus

• Water

6. CHEESE & MILK

• 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.

Using Cheese in Cooking

6. CHEESE & MILK

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7. Legumes, Vegetables & Fruit

• Plants with seeds that grow in special fruits known as pods

• Legumes – pods

• Pulses – edible dried seeds within the pods

7. LEGUMES, VEGETABLES & FRUIT

Legumes & Pulses

• Legumes

– French beans– Long beans

Types of Legumes & Pulses

• Pulses

– Peas– Lentils– Peanuts

7. LEGUMES, VEGETABLES & FRUIT

Nutrients in Legumes & Pulses

• 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

• Plants or plant parts that are used as food

Vegetables

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

TubersPotato, sweet potato, yam, tapioca, water chestnut

Carbohydrates, vitamin C

Roots Carrot, turnipCarbohydrates, vitamin A, B6 & C, calcium

7. LEGUMES, VEGETABLES & FRUIT

Types of Vegetables

Types Examples Nutrients

Bulbs Onion, garlicCarbohydrates, vitamin A, B6 & C, calcium

Flowers Cauliflower, broccoliVitamin A, B-group, C & E, folic acid, potassium, phosphorus, magnesium

FruitsTomato, cucumber, eggplant

Vitamin A, B-group & C, potassium

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 pressured-cooked.

• Soft vegetables such as tomatoes & fresh mushrooms may be grilled.

7. LEGUMES, VEGETABLES & 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.

Fruit

7. LEGUMES, VEGETABLES & FRUIT

Types of Fruit

Types ExamplesStone 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

• Carbohydrates

• Fibre

• Calcium

• Iron

• Vitamin A, B-group & C

• Potassium

• Phosphorus

• Manganese

• Water

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.

7. LEGUMES, VEGETABLES & FRUIT

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.