Food tests

• What is the aim for these practicals?

  To identify carbohydrates, proteins, and fats in food samples.
• The steps:

  • Starch (Iodine Test) → Add iodine → Blue-black = starch present.
  • Glucose (Benedict’s Test) → Heat with Benedict’s solution → Red/orange = sugar present.
  • Proteins (Biuret Test) → Add Biuret solution → Purple = protein present.
  • Lipids (Sudan III Test) → Add Sudan III → Red oil layer forms.
• What is the independent variable?

  Type of food sample.
• What is the dependent variable?

  Colour change.
• What is the control variable?

  Volume of reagents.