food tests - required practicals

• how to test for starch;

  1. place 2cm3 food solution in a test tube.
  2. add iodine (orange colour) if starch present it turns blue-black
• how to test for suagrs/gluclose;

  1. place 2cm3 of food solution in a test tube.
  2. add 10 drops of benedicts solution (blue colour)
  3. place test tube in beaker and half full the beaker with water from kettle
  4. leave for five minutes, if a little sugar is present it'll change to a green colour, if more sugar is present it turns into a yellow colour, if alot is present it turns red.
• how to test for protein;

  1. 2cm3 of food solution
  2. add 2cm3 of biuret solution (blue colour) if protein present it'll turn purple colour.
• how to test for lipids/fats;

  1. do not filter this solution as can stick to filter paper.
  2. add a few drops of distilled water + ethanol to 2cm3 of food substance.
  3. gently shake , if present it becomes cloudy