B2- Food tests

• What is the first step in preparing a food sample for testing?

  Break it up using a pestle and mortar
• Why do you add distilled water to the ground food sample?

  To dissolve some of the food
• What is the purpose of filtering the solution after mixing the food sample with water?

  To remove solid bits of food
• What are the steps involved in the Benedict's test for reducing sugars?

  1. Prepare a food sample and transfer 5 cm³ to a test tube.
  2. Set a water bath to 75 °C.
  3. Add about 10 drops of Benedict’s solution.
  4. Place the test tube in the water bath for 5 minutes.
  5. Observe the color change: blue to green, yellow, or brick-red indicates reducing sugars.
• What color does the Benedict's solution turn if reducing sugars are present?

  Green, yellow, or brick-red
• How do you test for starch using iodine solution?

  1. Prepare a food sample and transfer 5 cm³ to a test tube.
  2. Add a few drops of iodine solution.
  3. Gently shake the tube to mix.
  4. A color change from browny-orange to black or blue-black indicates starch presence.
• What color change indicates the presence of starch in a food sample?

  From browny-orange to black or blue-black
• What is the procedure for the Biuret test for proteins?

  1. Prepare a food sample and transfer 2 cm³ to a test tube.
  2. Add 2 cm³ of biuret solution.
  3. Gently shake to mix.
  4. A color change from blue to purple indicates protein presence.
• What color indicates the presence of protein in a food sample using the Biuret test?

  Purple
• How do you test for lipids using Sudan III stain solution?

  1. Prepare a food sample and transfer about 5 cm³ to a test tube.
  2. Add 3 drops of Sudan III stain solution.
  3. Gently shake the tube.
  4. A bright red top layer indicates the presence of lipids.
• What happens to the mixture if lipids are present when using Sudan III stain solution?

  It separates into two layers with a bright red top layer
• Why is it important to conduct a risk assessment before performing food tests?

  Because there are a lot of chemicals to use
• What is the first chemical used to test for starch?

  Iodine solution
• What is the purpose of the pestle and mortar in food testing?

  To break up the food sample
• What is the significance of the temperature in the Benedict's test?

  It helps to facilitate the reaction for detecting reducing sugars
• How do the tests for sugars, starch, proteins, and lipids differ in terms of the indicators used?

  Each test uses a different chemical indicator to detect specific food molecules