Detection of commonly used adulterants in milk

 

Practical Notebook Biology Standard XII

Biology 

Answeres

Practical Notebook
Standard XII

Class-12th

science

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13. Detection of commonly used adulterants in milk 

 The most common adulterants found in milk are urea, insecticides, NallCO,, vegetable oil, sucrose, starch, etc. 

 Aim: 

To detect the presence of excess water added to the milk by using a lactometer.  Requirements: Lactometer, measuring cylinders (500 ml capacity), thermometer, and milk samples (minimum 3, preferably raw milk, of the same animal source cow/buffalo) 

Theory: 

Animal husbandry plays a major supporting role in the rural economy.  Milk collection centers and cooperative societies play an integral role in delivering the milk from the cowsheds to the customers.  The addition of water to milk can be a big problem.  Hence water content of the milk is checked at any level before it reaches the customer.  Pure milk has a specific gravity of 1-032; the addition of water to it reduces this value.  FAO (Food and Agriculture Organization of the United Nations suggested that the standard specific gravity of milk ranges between 1-026 to 1-032 g / ml. Principle: The use of lactometer is the most widely used method for detection of specific gravity of milk.  Lactometer is a hydrometer with a limited scale (close to the range of the specific gravity of milk) Lactometer works on the principle of fluid displacement. Lactometer is an instrument sensitive to temperature, hence, the temperature of the milk sample must always be noted along with the reading of the lactometer. Temperature calibration must be either added or subtracted from the reading on the lactometer, to get the final specific gravity of the milk sample. Figure: Fig. Experimental setup Procedure: • Prepare three measuring cylinders (500 ml capacity).  and label them 1,2, and 3. • Pour milk samples gently, in each measuring cylinder. • Let the lactometer sink gently in the milk sample. Read and record the last lactam enter degree reading ("L) just above the surface of the milk.  Note down the temperature of each milk sample by using a thermometer.  .  If the temperature of the milk is different from that of calibration temperature of the lactometer 20 ° C), then calculate temperature correction. For every 10 C above the calibration temperature, add 0.2 ° L to the actual lactometer reading.  For every 10 ° C below the calibration temperature, subtract 0.2 ° L from the actual lactometer reading