food tests

• what test is used to test for sugars:

  • Benedict's test
• Once you add the Benedict's solution, you must heat it in a water bath for 5 minutes at 75°C
• what test is used to test for starch:

  • iodine
• if starch is present the colour will change from orange to black
• what test is used to test for proteins:

  • biurets solution
• if protein is present the colour change is:

  • Blue to lilac / purple
• what reagent is used to test for lipids:

  • Sudan III stain
• Sudan III test for lipids:

  • Place 5cm3 of your food sample in a test tube.
  • Add 3 drops of Sudan III stain solution. 
  • Gently shake.
  • If a red layer separates out on top, then lipid was present.