Food Commodities: Milk, Vegetables and Fruits

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MILK

Milk is a creamy, nutritious liquid produced by female mammals for feeding their young. The commonest in use is cow milk. Milk is nature’s perfect food for children since it contains almost all the food nutrients, although not enough for adults. It is also valuable in the diet of invalids and convalescents because it is readily digested and highly nutritive.

FOOD VALUE OF MILK

  1. a) Protein: Milk has 3.5% protein. The major protein is casein, while others are albumen and globulin.
  2. b) Carbohydrate: It contains carbohydrate in form of lactose (disaccharide).
  3. c) Fat: Milk also contains fat in form of very fine emulsion which is easily digestible.
  4. d) Minerals: It contains mineral salts such as calcium, phosphorus and iron in small quantities.
  5. e) Vitamins: Fat-soluble vitamins are present (A&D) in milk. It also contains vitamin b-complex such as B1, B2 and B12.
  6. f) Water: Milk contains approximately 87.2% water.

TYPES OF MILK

  1. Fresh Whole milk: This is the milk obtained directly from the cow in which nothing has been removed. The entire nutrients are intact.
  2. Skimmed milk: The fat content has been removed so it solely contains protein, carbohydrate, vitamins and minerals.
  3. Semi – Skimmed milk: comes homogenized and pasteurized and has a fat content of between 1.5% and 1.8%
  4. Dried or powdered milk:  Over 90% of the water content is removed, then it is milled to powder form.
  5. Evaporated milk: This is whole milk from which 60% of the water content had been removed.
  6. Condensed Milk: This is evaporated milk to which a safe and suitable sweetener has been added. It is sweeter and thicker than evaporated milk.
  7. Soya milk: It is obtained from vegetable source (soya beans) can be offered as an alternative to vegans and people with intolerance to cow milk.
  8. Rice milk: It is obtained from white rice. It is an alternative to dairy milk for vegans and those with an intolerance to lactose.
  9. Coconut milk: It is high in saturated fats.  It can be served as a drink, but it is more often used as an ingredient and a base for sauces.

EVALUATION

  1. Mention the food values of milk.
  2. List and explain three types of milk.

DIGESTIBILITY OF MILK

When milk enters the stomach, it separates into solids (clots). Digestibility depends on the size of the clots formed. Large clots make digestion difficult. The density of the clots depend on:

  • The amount of calcium and casein the milk contains.
  • The degree of acidity of the gastric juice. 

Ways of making milk more digestible

  1. Dilution with: a) water    b)  lime juice
  2. Aeration e.g. soda water
  3. By eating with solid or thick food e.g. porridge. This will prevent the milk from forming large clots.
  4. By boiling/heating. Boiled milk clots more slowly and gives a less dense clot than raw milk.

STORAGE OF MILK

Milk is a perishable product and therefore must be stored with care. It will keep for four to five days in refrigerated conditions. Milk can easily be contaminated and therefore stringent precautions are taken to ensure a safe and good quality product for the consumer.

Storage points

  1. Fresh milk should be kept in the container in which it is delivered.
  2. Milk must be stored in the refrigerator.
  3. Milk should be kept covered as it absorbs strong smells such as onion or fish.
  4. Fresh milk and cream should be purchased daily.
  5. Tinned milk stored in a cool, dry ventilated room.
  6. Dried milk is stored in air tight tins and kept in a dry store.

PRESERVATION OF MILK/HEAT TREATMENT

The common methods of preserving milk are:

  1. EVAPORATION: This is removing a large proportion of water from milk.
  2. DEHYDRATION: This is removal of virtually all the water content from milk and then milled to powder. It is done at a very high temperature.
  3. PASTEURIZATION: Milk is heated to a temperature of  65ºC for 30 minutes  and then cooled quickly. This is done to destroy the pathogenic microorganisms.
  4. STERILIZATION: The milk is heated up to 120ºC for up to an hour and then cooled rapidly. It is meant to destroy all the viable microorganisms.
  5. U.H.T (ULTRA-HIGH-TEMPERATURE): Milk is homogenized and then heated to temperature of at least 135ºC for 1 second the milk is then packaged under sterile conditions.
  6. HOMOGENIZATION: Milk is forced through a fine aperture that breaks up the fat globules to an even size so that they stay evenly distributed throughout and therefore do not form a cream line.

EVALUATION

  1. List and explain three methods of preserving milk.
  2. State two ways of making milk more digestible.

USES OF MILK

Milk is used in:

  • Soups and sauces.
  • The making of puddings, cakes and sweet dishes.
  • The cooking of fish and vegetables.
  • Hot and cold drinks.

MILK/DIARY PRODUCTS

CHEESE

It is made from milk. It takes approximately 5 litres of milk to produce ½ kg of cheese. Cheese is made from milk coagulated by an enzyme such as rennet (an animal product).  For vegetarian cheese, a non-animal enzyme is used.

Types of cheese

  1. Hard cheese e.g. cheddar, Cheshire, parmesan.
  2. Semi hard cheese e.g. Caerphilly
  3. Soft/ Cream Cheese e.g. Camembert
  4. Blue-vein cheese e.g. Irish blue, Danish blue
  5. Cheese spread e.g. samsoe and gourds

Uses of cheese

–   Soups, pasta, egg, fish and vegetable dishes, savouries

–   Can be consumed as snacks.

–   Acts as an additional flavouring.

–   Can be used to supplement carbohydrate foods

–   As a main ingredient in dishes e. g. it can be served as a substitute for meat in vegetarian dishes.

YOGHURT

It is produced by bacterial fermentation of milk. The bacteria used to make yoghurt are known as “yoghurt culture”. The bacteria act on lactose to produce lactic acid, which also acts on milk protein to give yoghurt its texture and characteristic ‘tart flavour’.

Uses of yoghurt

–   It can be consumed in hot climates as refreshing meal.

–   It can be added to dishes to improves their flavour e.g. in gravies sauces.

–   It adds variety and flavour to curries, stew and rice dishes.

–   It can be added to salad dressing.

EVALUATION

  1. Mention three types of cheese.
  2. State two uses of yoghurt.

VEGETABLES

Vegetables are plants or parts of plants cultivated for food. They are highly perishable, but very essential.

CLASSIFICATION OF VEGETABLES

  1. Root e.g. Swedes, turnips, radishes, carrots, parsnip, breet roots.
  2. Tubers e.g. potatoes, yam, cassava, cocoyam, etc.
  3. Bulbs or swollen leaves e.g. onions, shallot, leeks, garlic, etc.
  4. Green leaves e.g. cabbage, lettuce, sprout, spinach, water leaves, etc.
  5. Brassicas or Flowers e.g. cauliflower, broccoli, Brussels sprout, etc.
  6. Fruits e.g. tomatoes, marrow, cucumber, pepper, pumpkin, etc.
  7. Pods and seeds e.g. pea, soya beans, runner beans, okra, groundnuts, etc.
  8. Stems and shoots e.g. asparagus, celery, sapphire, etc.
  9. Miscellaneous e.g. mushroom, garden eggs, fungi, etc.

FOOD VALUES OF VEGETABLES

  1. Protein: The proteins in vegetables are second class protein and are found in pods and seeds. Recent discovery shows that soya beans and moringa contain first class protein and can compete with animal proteins.
  2. Carbohydrate: They are present in form of starch, sugar and cellulose.
  3. Mineral salts: Minerals such as phosphorus and calcium are present in some leafy and root vegetables.
  4. Vitamins: Vitamins A, B and C are present in vary quantities in vegetables.
  5. Water: All vegetables contain water in vary degrees.

EVALUATION

  1. Mention three nutrients that can be obtained from vegetables.
  2. List five classes of vegetables with examples.

QUALITY AND PURCHASING POINTS

Root Vegetables

  • Must be clean and free from soil.
  • They must be firm, sound and free from spade marks.

Green Vegetables

  • They must be absolutely fresh.
  • The leaves must be bright in colour, crisp and not withered.
  • Cabbage and Brussels sprouts should have tightly growing leaves and be compact.
  • Pea and beans should be crisp and of medium size. Pea-pods should be full.
  • Blanched stems must be firm, white, crisp and free from soil.

STORAGE OF VEGETABLES

  1. Store all vegetables in a cool and dry ventilated room.
  2. Check vegetables daily and discard any that is unsound.
  3. Root vegetables should be emptied from sacks and stored in bins or racks.
  4. Green vegetables should be stored on well ventilated racks.
  5. Storage should be for short time as vegetables loose value especially vitamin C when stored for long period.

PRESERVATION OF VEGETABLES

  1. Canning: Vegetables are preserved in tins e.g. carrots, mushroom, peas, etc.
  2. Dehydration/Drying: The water content is removed by sun-drying or other means e.g. leaf vegetables, tomatoes, pepper, etc.
  3. Pickling: Vegetables are preserved in spiced vinegar e.g. onions, red cabbage, etc.
  4. Salting: Vegetables such as runner beans are spiced and preserved in dry salt or brine.
  5. Freezing: Deep freezing can be used to preserved vegetables such as peas, cauliflower, etc.

EVALUATION

  1. State three ways of storing vegetables.
  2. List and explain two methods of preserving vegetables.

FRUITS

Fruits are the fleshy seed-bearing part of plants. It is the complete structure formed by the ripened ovary of a flowering plant. Fruits are classified into two broad groups, which are;

FRESH FRUITS

  1. a) Soft fruits: These include different types of berries such as raspberries, strawberries, loganberries, goose berries, black berries, red and black currants, banana, guava, etc.
  2. b) Hard fruits e.g. apples, pears, mangoes, melon, etc.
  3. c) Stone fruits e.g. cherries, damsons, plums, apricots, greengage, peaches, nectarines
  4. c) Citrus fruits e.g. oranges, lemons, grape, mandarins, lime, tangerines, Satsuma
  5. d) Tropical and other fruits e.g. pineapples, pawpaw, melon rhubarbs, sour- sop, etc.
  1. DRIED FRUITS: These include figs, dates, apricots, etc.

NUTRITIVE VALUE OF FRUITS

  1. Vitamins: Fruits major content is vitamin C (ascorbic acid). Some may contain B-group of vitamins and carotene.
  2. Carbohydrates: Fruits contain carbohydrates in form of fructose and glucose. They also contain starch and cellulose which add bulk to the stools.
  3. Minerals: Fruits contain some organic acids such as citric, malic, tartaric, etc. which are responsible for the sour taste of unripe fruits.

EVALUATION

  1. Mention the classification of fruits with examples.
  2. What are the nutrients present in fruits.

WAYS OF SERVING FRUITS

  1. Fresh fruits can be served whole, fresh, ripe and raw.
  2. The juice can be squeezed out and served as fruit juices.
  3. The squeezed juice can be diluted with syrup to make fruit drinks.
  4. Fruits can also be served in form of fruit salads.
  5. Some fruits can be used to make preserves such as jams, jellies and marmalades.

POINTS TO CONSIDER WHEN PUCHASING FRUITS

  1. The fruits must be fresh.
  2. They must be free from insect infestation.
  3. They must not be over-ripe.
  4. The fruit must also be firm to touch.
  5. Always make use of fruits in-season.

Methods of Preservation of fruits

  1. Drying: Fruits such as figs, dates, apricots, etc. can be preserved by drying.
  2. Canning: Almost all fruits can be canned.
  3. Bottling: Fruits are commercially preserved in this way e.g. cherries.
  4. Quick freezing: Strawberries, raspberries, apples, etc. are frozen below -18ºC.
  5. Cold storage: Apples are stored at temperature between 1-4ºC depending on the variety of the apples.
  6. Gas storage: Fruits are kept in a sealed storeroom where the atmosphere is controlled.

GENERAL EVALUATION

  1. List and explain four types of milk.
  2. List the classification of vegetables.
  3. State ways of serving fruits.
  4. State three uses of eggs.
  5. State three safety precautions in catering establishments.
  6. State three ways of serving fruits.
  7. State four methods of preserving fruits.

WEEKEND ASSIGNMENT

  1. A white creamy fluid extracted from the breast of a female mammals is called ____. A. water B. syrup milk             D. juice
  2. A type of milk that the fat content is 0.1% is ___. A. organic milk B.  skimmed milk
  3. condensed milk D.  powdered milk
  4. Which of these is a major nutrient found in vegetables? A. Protein B. Ascorbic acid
  5. Calcium D. Vitamin D
  6. Citrus fruits include all of these except ____ A. oranges B.  grapes C.  lime D. pineaaple
  7. Milk is a major source of high quality protein; the major protein in milk is ___ A. casein
  8. albumen C. glucose D.  amino acid

THEORY

  1. Write short notes on any five types of milk.
  2. List the classification of fruits.

    See also

    METHODS OF COOKING – DRY HEAT, Baking, Roasting & Grilling

    METHODS OF COOKING: Stewing, Frying, advantages & disadvantages

    METHODS OF COOKING: Boiling, Poaching & Steaming

    COOKING OF FOODS

    FLOUR COOKERY: Types of flour, Raising Agents & Flour mixtures

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