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.