Unit II

Unit 2: Common Foods and Adulteration Methods for Detection of Common Adulterants

Detection of Adulterants in Milk

  • Milk Adulterant: Starch

    • Method of Detection:

      • Add a few drops of iodine solution.

      • Observation: Blue color indicates presence of starch.

  • Milk Adulterant: Urea

    • Method of Detection:

      • Take 1 tsp of milk in a test tube.

      • Add ½ tsp soybean or pigeon pea powder.

      • Mix by shaking and dip red litmus paper after 5 minutes.

      • Observation: Color change from red to blue indicates urea presence.

  • Milk Adulterant: Vanaspati

    • Method of Detection:

      • Take 3 ml milk in a test tube, add 10 drops hydrochloric acid, and 1 tsp sugar.

      • Observation: Red coloration indicates the presence of vanaspati.

  • Milk Adulterant: Formalin

    • Method of Detection:

      • Add 5 ml concentrated sulfuric acid to 10 ml milk from the side of the test tube without shaking.

      • Observation: Violet or blue ring indicates presence of formalin.

  • Milk Adulterant: Detergent

    • Method of Detection:

      • Shake 5-10 ml milk sample with equal water.

      • Observation: Formation of foam indicates presence of detergent.

  • Milk Adulterant: Synthetic Milk

    • Method of Detection:

      • Bitter aftertaste and soapy feel on rubbing; turns yellow when heated.

Detection of Common Adulterants in Milk-based Products

  • Sweet Curd Adulterant: Vanaspati

    • Method: Like milk with hydrochloric acid.

  • Khoa and Products Adulterant: Starch

    • Method: Boil sample, cool, add iodine; blue color indicates starch.

  • Paneer Adulterant: Starch

    • Method: Similar to Khoa.

Detection of Common Adulterants in Oils and Fats

  • Ghee Adulterant: Vanaspati or Margarine

    • Method: Mix ghee with hydrochloric acid and sugar; crimson color indicates presence.

  • Edible Oil Adulterant: Restricted Color

    • Method: Shake oil with hydrochloric acid; color separates in the upper layer.

  • Coconut Oil Adulterant: Any Other Oil

    • Method: Refrigerate oil; adulterant remains liquid.

Detection of Common Adulterants in Sweetening Agents

  • Sugar Adulterant: Chalk Powder

    • Method: Dissolve in water; chalk settles.

  • Honey Adulterant: Sugar Solution or Water

    • Method: Cotton wick in honey should burn; if not, water is present.

  • Jaggery Adulterant: Washing Soda

    • Method: Add HCl; effervescence indicates washing soda.

  • Ice Cream and Beverages Adulterant: Metanil Yellow

    • Method: Extract color with warm water, add HCl; magenta indicates adulteration.

Detection of Common Adulterants in Food Grains

  • Wheat, Rice, Maize, etc. Adulterants:

    • Dust, pebbles, and insects are examined visually.

  • Maida/Rice Adulterant: Boric Acid

    • Method: Shake with water, add HCl; turmeric paper turning red signifies boric acid.

Specific Tests for Various Food Articles

  • Black Pepper Adulterant: Papaya Seeds

    • Separation by visual characteristics; papaya seeds are lighter.

  • Turmeric Powder Adulterant: Colored Saw Dust

    • What to do: Add HCl, observe color changes.

Miscellaneous Tests

  • Saffron Adulterant: Dried Tendrils of Maize Cobs

    • Method: Genuine saffron will not break easily. Color dissolves in water indicates artificial.

  • Common Salt Adulterant: White Powdered Substances

    • Method: Stir and watch for insoluble impurities.

  • Iodized Salt Adulterant: Common Salt

    • Method: Potato test with lemon juice; blue indicates iodized salt.

Processed Food and Adulterants

  • Processed foods include those altered from their raw state (like canning, preservatives, etc.).

    • Various cheap substitutes and metallic substances can be added, detectable through chemical tests.