Q2. How can we detect adulteration in food items? Describe the methods for detection of adulterants in any five food items?
Answers
Answer:
1)Milk water The presence of water can be by putting a drop of milk on a polished slanting surface. The drop of pure milk either or flows lowly leaving a white trail behind it, whereas milk adulterated water will flow immediately without leaving a mark
2 ) Starch Add a few drops of tincture of Iodine or Iodine solution. Formation of blue colour indicates the presence of starch. Iodine solution is easily available in the medical
stores.
3 ) Urea Take a teaspoon of milk in a test tube. Add ½ teaspoon of soybean or arhar powder. Mix up the contents thoroughly by shaking the test tube. After 5 minutes, dip a red litmus paper in it. Remove the paper after ½ a minute. A change in colour from red to blue indicates the presence of urea in the milk.
4 ) Vanaspati Take 3 ml of milk in a test tube. Add 10 drops of hydrochloric acid. Mix up one teaspoonful of sugar. After 5 minutes, examine the mixture.The red colouration indicates the presence of vanaspati in the milk.
5 )Formalin Take 10 ml of milk in a tests tube and add 5 ml of conc. sulphuric acid from the sides of the wall without shaking. If a violet or blue ring appears at the intersection of two layers then it shows presence of formalin. Formalin enhances the life of milk and thus is
added for preservation
purpose.
6 ) Detergent Shake 5-10 ml. of sample with an equal amount of water lather indicates the presence of detergent.
7 )Milk Synthetic milk Synthetic milk has a bitter after taste, gives a soapy feeling on rubbing between the fingers and turns yellowish on heating.
8) Synthetic milk-test for protein The milk can easily be tested by Urease strips (available in the Medical stores) because Synthetic milk is devoid of protein.
9 ) Test for Glucose/
inverted sugar Milk does not contain glucose /invert sugar, if test for glucose with urease strip found positive.It means milk is adulterated. If it is made synthetically by adding while colour water paint. Oils, alkali,
urea and detergent
etc. Glucose, inverted
sugar syrup is added in milk to increase the
consistency and test
10( Ghee, cottage
cheese, condensed
milk, khoa, milk
powder etc, Coal Tar Dyes Add 5 ml of dil. H2SO4 or conc. HCL to one teaspoon full of melted sample in a test tube. Shake well. Pink colour (in case of H2SO4) or crimson colour (in case of HCl) indicates coal tar dyes. If HCl does not give colour dilute it with water to get the colour.
11) Sweet Curd Vanaspati Take1 teaspoon full of curd in a test tube. Add 10 drops of hydrochloric acid. Mix up the contents shaking the test tube gently. After 5 minutes, examine the mixture. The red colouration indicates the presence of vanaspati in the curd.
12 Rabri Blotting paper Take a teaspoon of rabri in a test tube. Add 3 ml of hydrochloric acid and 3 ml of distilled water. Stir the content with a glass rod. Remove the rod and examine. Presence of fine fibres to the glass rod will indicate the presence of blotting paper in rabri.
13 Khoa and
its products Starch Boil a small quantity of sample with some water, cool and add a few drops of Iodine solution. Formation of blue colour indicates the presence of starch.
14 Chhana or
Paneer Starch Boil a small quantity of sample with some water, cool and add a few drops of Iodine solution. Formation of blue colour indicates the presence of starch.