testing foods

• Starch test:

  • Add iodine solution to food solution.

  • Starch present — dark blue/black colour.
• Lipids:

  • Add ethanol to food solution.

  • Shake test tube and wait for a minute.

  • Pour ethanol into a test tube of water.

  • Iodine present — solution turns cloudy.
• Reducing sugars: (emulsion test)

  • Add benedict’s solution.

  • Heat in a water bath.

  • Sugars present — orange/red colour.
• Proteins:

  • Add biuret’s reagent (copper sulfate and sodium hydrocarbons solution).

  • Shake solution and wait a few minutes.

  • Protein present — blue to purple.