Food tests

• What is the purpose of food tests?

  To identify what type of food molecule a sample contains
• What are the steps to prepare a food sample for testing?

  1. Break up the food using a pestle and mortar
  2. Transfer to a beaker and add distilled water
  3. Stir the mixture with a glass rod
  4. Filter the solution using a funnel lined with filter paper
• What is the first step in the Benedict's test for sugars?


  Prepare a food sample and transfer 5 cm³ to a test tube
• At what temperature should the water bath be set for the Benedict's test?

  At 250°C
• What color change indicates the presence of reducing sugars in the Benedict's test?

  The solution changes from blue to green, yellow, or brick-red
• What is the purpose of the iodine solution in food testing?

  To test for the presence of starch
• What color change occurs if starch is present when using iodine solution?


  The solution changes from browny-orange to black or blue-black
• What is the Biuret test used for?

  To test for the presence of proteins
• What color indicates the presence of protein in the Biuret test?

  The solution changes from blue to pink or purple
• What is the Sudan III test used for?

  To test for the presence of lipids
• What happens to the mixture in the Sudan III test if lipids are present?

  The mixture will separate into two layers, with a bright red top layer
• What does it mean if no separate red layer forms in the Sudan III test?

  It indicates that no lipids are present
• What are the types of food molecules tested in food tests?

  • Sugars (reducing and non-reducing)
  • Starch
  • Proteins
  • Lipids
• What types of foods commonly contain starch?

  Pasta, rice, and potatoes
• What types of foods are rich in proteins?

  Meat and cheese
• What types of foods commonly contain lipids?

  Cooking oil, margarine, and milk
• What safety precautions should be taken during food testing?

  • Conduct a risk assessment
  • Use appropriate protective equipment
  • Handle hot equipment carefully