SB1f- Testing foods

    Cards (13)

    • What is the test for sugars?
      Benedict's test
    • What is the test for starch?
      Iodine test
    • What is the test for proteins?
      Biuret test
    • What is the test for lipids?
      Emulsion test
    • What colour does the sample turn if sugars are present?
      Brick red
    • What colour does the sample turn if starch is present?
      Blue-Black
    • What colour does the sample turn if protein is present?
      Lilac
    • What colour does the sample turn if lipids are present?
      Milky white emulsion
    • How do you prepare the food sample?
      • Get food and break it up with a mortar and pestle
      • Put crushed food and put it in a beaker with some distilled water
      • Stir it with a glass rod until some of it dissolves
      • Filter out the solution
      • The solution we end up with is our sample
    • Benedict's test for reducing sugars
      • Transfer 5cm³ of the sample to a test tube
      • Prepare a water bath to 75 celcius
      • Add about 10 drops of Benedicts solution to the test tube
      • Place it in the water bath for 5 minutes with a test tube holder
      • If there is no reducing sugars it will stay blue, but if there is reducing sugars it will turn brick red.
    • Iodine test
      • Take 5cm³ of food sample and add a few drops of iodine solution
      • This turns the solution brown
      • Shake the sample
      • If it contains starch, the solution will turn blue-black
    • Biuret test
      • Add 2cm³ of the sample in a test tube
      • Add 2cm³ of Biuret solution (Potassium hydroxide, then copper sulphate), turning it blue
      • Shake the solution
      • If protein is present, the solution will turn lilac
    • Emulsion test
      -Take food sample and add 2cm³ of ethanol and shake
      -Then add 2cm³ of distilled water
      -If it turns milky white, lipids are present
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