tests for food

• test for sugars

  • Add a few drops of Benedict’s solution to a test tube containing 5 cm cubed of the prepared food sample.
  • Put the test tube in a water bath at 80°C for 5 minutes
  • The blue Benedict’s solution will turn green, yellow or brick red if the solution contains a reducing sugar.
• test for starch

  • Add a few drops of iodine solution to a test tube containing some of the prepared food sample.
  • Gently shake the test tube to mix.
  • The brown-orange solution will turn blue-black in the presence of starch
• tests for proteins

  • Add 2cm cubed of biuret solution to 2cm cubed of your food sample
  • Shake the test tube gently to mix
  • If a protein is present, the solution will change from blue to pink/purple.
• test for lipids

  • Add three drops of Sudan III stain to a test tube containing the unfiltered prepared food sample.
  • Shake the test tube gently.
  • If a lipid is present, the solution will separate into 2 layers. The top layer will be the lipid and will be stained red by the Sudan III stain