Adulteration of Food-Meaning,Adulteration in Milk and Pulses

  1. Glucose

Usually poor quality glucose is added to milk to increase the lactometer reading. There are    two tests available to detect the adulteration of milk with glucose.

         Method of Detection

  • Phosphomolybdic or Barford Test

Take 3 ml of milk in a test tube and add 3 ml Barford’s reagent and mix it thoroughly. Then keep it in a boiling water bath for 3 min and then cool it for 2 min by immersing in tap water with out disturbance. Then add 1 ml of phosphomolybdic acid and shake. If blue colour is visible, then glucose is present in the milk sample.

  • Diacetic test

Take a strip of diacetic strip and dip it in the milk for 30 sec to 1 min. If the strip changes colour, then it shows that the sample of milk contains glucose. If there is no change in the colour of the strip, then glucose is absent. In this method the presence of glucose in milk can be quantified by comparing the colour developed with the chart strip.

  1. Skim milk powder in milk

            Method of Detection

  • If the addition of nitric acid drop by drop in to the test milk sample results in the development of orange colour, it indicates the milk is adulterated with skim milk powder. Samples with out skim milk powder shows yellow colour.
  1. Buffalo milk in cow milk

          Method of Detection

  • The presence of buffalo milk in cow milk is tested by Hansa test. It is based on immunological assay. One ml of milk is diluted with 4 ml of water and then it is treated with 1 ml of antiserum. The characteristic precipitation reaction indicates the presence of buffalo milk in the sample taken. (The antiserum is developed by injecting buffalo milk proteins into rabbits).
  1. Ammonium Sulphate

  Method of Detection

  • Take 5 mli of hot milk in a test tube. Add a suitable acid, e.g. Citric acid. The whey obtained is separated and filtered. Take the whey in another test tube and add 0.5 ml of 5% Barium Chloride. Appearance of precipitate indicates the presence of Ammonium Sulphate.
  • Take 5 ml of milk in a test tube. Add 2.5 ml of 2% Sodium Hypochlorite and 2.5 ml of 5% Phenol Solution. Heat for 20 seconds in boiling water bath. If blish colour turns to deep blue, it indicated the presence of Ammonium Sulphate. However in case it turns pink, it shows that the sample is free from Ammonium Sulphate.
Adulteration of Food-Meaning,Adulteration in Milk and Pulses

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