Adulteration of milk

FOOD SCIENCE AND PROCESSING 3 (2+1)
Lesson 26 : Processing and preparation of Milk and Milk products

Adulteration of milk

  1. Milk is commonly adulterated with water, starch or removal of fat, addition of sweetener or colour or preservative or addition of milk powder.
  2. Fat shows the greatest variation of milk. Consequently solids – non fat is determined and the value for a sample of milk is close to 7.5 – 10.6%. The bottom of the range should be surely a case of adulteration.
  3. Milk serum or whey that portion of the milk from which both fat and casein have been removed is constant in composition and analysis of it is often used in attempting to detect watering. If milk has been watered the solids are present in lower concentration and the specific gravity will be closer to water than for pure milk. Lactometer is used to find out the specific gravity. The normal specific gravity of milk is 1.03.
  4. One of the most reliable physical constants of milk is its freezing point. The presence of dissolved substances, the salts, the lactose and other molecules depress the freezing point of milk below 0°C. Normal freezing point of milk is – 0.55°C. Milk which has been watered will have freezing point closer to zero.
  5. Skimming of milk or the addition of skimmed milk to ordinary milk does not change the amount of the any components except fat. It can be detected by calculating the ratio of the fat to protein lactose, solids or solids-non-fat.
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Last modified: Tuesday, 13 December 2011, 7:52 AM