Dairy Products

Milk and Cheese

Milk

• Products of milk (dairy products)

1. Butter

2. Cream

3. Cheese

Milk• Types of milk1. Untreated2. Pasteurised3. Homogenized4. Sterilized5. Ultra-high temperature (UHT)6. Evaporated7. Condensed8. Powdered9. Skimmed

Milk

• Types of milk1. Untreated milk: - has not gone through any kind of heat

treatment- bottled on the farm

2. Pasteurized milk:- given mild heat treatment (72’C for 15

seconds) to destroy most disease-carrying germs

Milk

• Types of milk

3. Homogenised milk: pasteurised milk processed to disperse the fat globules and distribute them evenly throughout the milk

4. Sterilised milk: homogenised milk heated to a high temperature (113’C) for 15 – 40 minutes

Milk• Types of milk5. Ultra-high temperature

(UHT) milk: homogenised milk heated to a high temperature of 132’C for not more than one second

- can be kept for months without refrigeration

Milk• Types of milk6. Evaporated milk: some water has been

removed from the milk through evaporation

- contains 25% less water than fresh milk - sterilised at 115.5’C for 20 minutes7. Condensed milk: some water has been

removed from milk through evaporation - sweetened with sugar

Milk

• Types of milk

8. Powdered milk: all water has been removed (powder form)

9. Skimmed milk: fats have been skimmed off the milk

Nutritive Value of Milk

1. Proteins- High biological value- Caseinogen (80%), lactalbumin, lactoglobulin

2. Fats- In the form of very tiny droplets dispersed

throughout the milk (emulsion)- Milk fats are used in the production of cream

and butter

Nutritive Value of Milk3. Carbohydrate- In the form of lactose (milk sugar)

4. Vitamins- A, D, B1, B2

5. Minerals- Calcium- Phosphorus- Sodium- Chlorine- Potassium

6. Water: 87%

Effect of Heat on Milk• When milk is boiled, proteins coagulate

and form a layer on the surface.

• As boiling continues, hot air and steam get trapped under this layer.

• This results in milk overflowing from its container.

Cheese

• A concentrated form of milk

• It is a means of preserving nutritive value of milk

Types of Cheese

1.1. Very hard cheese: water content is 30 – 32% Very hard cheese: water content is 30 – 32% (Parmesan cheese: grated for sprinkling on (Parmesan cheese: grated for sprinkling on cooked food)cooked food)

2.2. Hard cheese: water content is 37 – 40% Hard cheese: water content is 37 – 40% (Cheddar cheese: grated for use in cooking)(Cheddar cheese: grated for use in cooking)

3.3. Soft cheese: water content is 50% (Cream Soft cheese: water content is 50% (Cream cheese, processed cheese and cottage cheese, processed cheese and cottage cheese: used as spreads on biscuits and for cheese: used as spreads on biscuits and for cheesecakes)cheesecakes)

Nutritive Value of Cheese• Contains practically all the nutrients found

in milk EXCEPT carbohydrates

• Lactose in milk is converted into lactic acid during the manufacturing of cheese

Effect of Heat on Cheese

• When cheese is heated, the fat melts and separates.

• Cheese becomes soft.

• On further heating, proteins over-coagulate and become stringy and tough.