MILK AND MILK PRODUCTS
WEEK 5
CLASS: SS 2
SUBJECT: FOOD AND NUTRITION
TOPIC: Milk and milk products
CONTENT:
Nutritive value of milk and milk products, Types of milk
Sub-Topic 1: Nutritive value of milk and milk products
Milk is a creamy liquid produced from the mammary glands of all female mammals for feeding their young ones. Milk can be produced from cows, horses, goats, sheep etc. The commonly used worldwide is cow milk. It is one of the most valuable foods containing practically all foods substance. It is sometimes regarded as nature’s perfect food but this is only true for babies , the nutrients are not in the correct proportions for adults , the proportions of carbohydrate is too law and it also lacks iron and vitamin C . Milk is extremely valuable in the diet of invalids and convalescent on account of its food value. It is richly digested.
Milk can be produced from cows, horses, goats, ewes, monkeys, dogs, sheep etc. Cow’s milk is the most commonly used worldwide.
Milk contains a wide range of nutrients. The composition of macro-nutrients (carbohydrates, fats and proteins) in milk is a balance one
(A) Carbohydrate: the type found in milk is lactose which is often called milk sugar. Lactose is digested by the enzyme lactase into simpler sugar that the body can absorb.
(B) Fat: the fat portion of milk, called the butter, is in form of minute globules which tend to rise to the milk to from a cream line. The fatty acids in milk are mostly of the saturated and mono-saturated types, although there are also small amount of poly unsaturated fatty acids in milk. The minimum content acceptable worldwide is 3.25%
(C) Protein: the protein in milk is of high quality. They are rich in all the essential amino acids. They are casein, lacto albumen and lacto globulin.
(D) Vitamins: milk contains both water-soluble vitamins e.g. thiamine, B1, riboflavin, B2, B12 and fat soluble vitamins such as A,D,E, and K. Milk also contains carotene which is responsible for the yellowish colour of milk at times.
(E) Minerals: milk contains all the trace elements known to be important to the body. E.g. zinc, iodine, selenium and chromium but relatively poor source of iron, copper and manganese. Milk is rich in some essential mineral elements such as calcium and phosphorus.
FAT CARBOHYDRATE WATER PROTEIN ASH
3.7% 4.9% 87.2% 3.5% 0.7%
Sub-Topic 2:
TYPES OF MILK
1. Fresh whole milk: This is the milk that is obtained directly from the cow in which none of the nutrients have been removed.
2. Skimmed milk: The fat content has been removed, and it is therefore made predominantly of protein, carbohydrate, minerals and vitamins.
3. Evaporated milk: This is whole from which about 60% of the water content has been removed.
4. Dried or powdered milk: Over 90% of the water content has been removed and it is then milled to powdered form.
5. Condensed milk: This is evaporated milk to which a safe and suitable nutritive sweetener usually sugar has been added. So it is sweeter and thicker than evaporated milk.
Methods of processing milk.
(A) PASTEURIZATION
Milk is heated for a short time (about 30 minutes) at a temperature below 1000C (nearly 700C) to kill at the harmful bacteria present in it. High temperature, short time (HTST) method is being used nowadays, i.e. milk is heated quickly to 710C, held at the temperature for 15seconds and cooled rapidly.
(B) HOMOGENIZATION
Milk is first pasteurized and then forced through a fine aperture under pressure. This breaks the fat globules, completely that a cream line is formed. The fat remains evenly distributed throughout the milk to obtain a homogenous fluid. This is usually achieved by passing the whole fresh milk though a very tiny nozzle in a special piece of equipment known as homogenizer.
(C) STERILIZATION
Milk is pre-heated and homogenized before filling into bottles which are closed in an air-tight seal (hermetically sealed). The bottles are then heated to 1040C – 110C and kept at this temperature for 20 to 30minutes. Sterilized milk contains no bacteria and the bottles are vacuum sealed and can thus be kept for several weeks without opening. The high temperature used in sterilization cause slight caramelization of the lactose producing a noticeable change in flavour and appearance. There is also reduction in the nutritive value with loss of one third of the thiamine (vitamin B1) and half of the ascorbic acid (vitamin C), folic acid and vitamin B12. Sterilized milk is a good stand by; with its creamy taste, it is ideal for puddings.
(D) EVAPORATED MILK: This is homogenized and concentrated (by removal of about 60% of its water content) to about half the volume of the original milk without adding sugar. It is sterilized in the can and some of the thiamine (B1) and vitamin C are destroyed.
(E) CONDENSED MILK: It is also a concentrated form of milk. It is made from whole skimmed or semi-skimmed milk with sugar added.
(F) DRIED MILK: Over 90% of the water content has been removed and it is then milled to powder. The ranges of dried milk available include skimmed milk, skimmed milk to which vegetable fat has been added known as filled milk.
(G) CULTURED OR FERMENTED MILK: Milk may be fermented with/of products specific microorganism to form a variety with characteristic level of acidity and flavour development. The best known milk produce is yoghurt. Others are cultured butter milk, ‘nono’, etc.
PLANT MILK SOURCE
Soya milk: the flour derived from soya bean milk is used to make a kind of milk which has about the same protein content as cow’s milk and can be used in a similar way.
Sub-Topic:3
TYPES OF MILK PRODUCT
Milk products include fermented and non-fermented varieties. Examples of fermented milk products are yoghurt, sour milk curds, cheese and local chesses called (wara). Milk products that are not fermented are butter, caesinates and milk ice-cream.
(a) Yogurt.
This is obtained from heat-treated, homogenized milk which is inoculated with a culture containing equal amount of Streptococcus thermophilus and Lactobacillus bulgaricus bacteria. The essential change produced by these bacteria is that the lactose in milk is
converted to lactic acid.
(b)
Cheese
There are more than 800 different types of cheese; the basic principles of manufacturing are the same. Milk is coagulated and the solid formed is cut into small pieces to allow the whey (the liquid part of the milk) to drain off. The curd (solid part of the milk) is dried, salt is added and the cheese and texture of the cheese is lightly pressed, a soft crumby cheese is produced but it’s more firmly pressed, a harder cheese is produced.
Types of cheese
The basic types of cheese evolved as a product of different types of milk regional environmental conditions, accidents and gradual improvements by trial and error. They are classified into:
– Soft unripened, e.g. cottage chesses, ripened, e.g. camembert
– Semisoft e.g. Munster, limburger, Roquefort, gorgonzola stallion, wenslaydale etc
– Hard e.g. cheddar, granular, Swiss, emmentaler, gruyere, caciocavallo
– Very hard, e.g. parmesan, Romano, sapsago, spleen, etc
– Whey cheese, e.g. my sost, primo’s, ricotta etc
Other types of English Cheese are Caerphilly, Cheshire, Derby, Dorset blue, Double Gloucester, Lancaschire, and Leicester
(c) Wara
This is a local cheese that is common in the northern part of Nigeria. It is produced by eh fermentation of milk protein. Whole milk is used for its production.
USES OF MILK
Uses
1. It can be drunk raw
2. It can be cooked, used as a basis of a large variety of dishes or as an accompaniment.
3. Milk products e.g. yoghurt is important in several ways:
(a) It can be taken in picnics, camping as dessert.
(b) It can be served on breakfast cereals;
(c) It can be served as refreshing meal course on a hot day
(d) It can be added to dishes to improve their flavour
(e) It adds variety and flavour to stews and ripe dishes
(f) It may be used with fruits and vegetable salad or added to salad dressing.
(g) It can be served with flans and pastries instead of cream
4. Cheese as a milk product is equally important in several ways;
(a) It has high food value
(b) It can be eaten raw and useful for sandwiches and quick meals.
(c) It can be used to supplement carbohydrate foods e.g. macaroni, cheese etc.
(d) It can be used in cooking as in sauces, scones, cheese pastries, pies, flans and cheese cake.
(e) It can be consumed as snack with bread or biscuits
(f) It can be used for small savoury dishes e.g. cheese straw.
5. Milk is an essential ingredient in the production of dishes and snacks such as rice or semolina pudding, milk shake, milk drink, pan cake etc.
EVALUATION
(1) List and explain the types of milk.
(2) List the types of milk products
(3) Discuss the nutritive value of milk and milk products
(4) Discuss the various types of milk
(5) Describe the nutritive value of milk
(6) State the uses of milk
(7) List the type of cheese
EVALUATION
Describe the pasteurisation and homogenisation of milk
ASSIGNMENT
Make a research to find out how local cheese [Wara] is prepared
OBJECTIVE TEST
1. What is the fat content of milk called? (a) fatty acids (b) glycerol (c) butter fat (d) fat globules
2. Which of these is milk from plant sources? (a) filled milk (b) homogenized milk (c) soya milk (d) condensed milk
3. Which of the type of milk has 90% of its water content removed? (a) cultured milk (b) dried milk (c) evaporated milk (d) butter milk
4. _________ is a soft unripened cheese. (a) cottage cheese (b) cheddar cheese (c) Swiss cheese (d) granola cheese
5. Which of these is a fermented milk product? (a) ice cream (b) cachinnates (c) “wara” (d) butter
6. Milk can be drunken ________. (a) raw (b) dried (c) boiled (d) cooked
7. Milk is often called perfect because it (a) is in liquid form (b) is easily digested (c) it contains second protein and fat (d) it contains all essential food values
8. The process whereby milk is heated and then cooled rapidly in order to destroy harmful germs is known as (a) sterilization (b) pasteurization (c) evaporation (d) condensation