Tests

Benedict’s Test for Reducing Sugars §

• Test for presence of reducing sugars with Benedict’s test
• Procedure:
  • If solid, grind food sample with distilled water with mortar and pestle before filtering the mixture to obtain filtrate
  • Add equal volume of Benedict’s reagent to 2cm of the filtrate or liquid
  • Shake the mixture
  • Heat a beaker of water until it boils.
  • Boil it in the boiling water bath for 2 minutes
  • Orange/Brick-red precipitate formed if reducing sugars found

Iodine Test for Starch §

• Test for the presence of starch
• Procedure:
  • add 2-3 drops of iodine solution to the food sample
  • Blue-black if starch present, orange-brown if starch not present

Ethanol Emulsion Test §

• Tests for the presence of lipids (fats)
• Procedure:
  • Add 2cm of ethanol to liquid food sample in a test tube
  • Shake thoroughly
  • Add 2cm of distilled water and shake
  • Cloudy white emulsion if fat is present

Biuret Test for Proteins §

• Test for the presence of peptide bonds (cannot test for amino acids!!!!)
• Procedure:
  • Add 2cm of sodium hydroxide solution () to food sample and shake thoroughly.
  • Add 1% copper(II) sulfate solution () drop by drop, shaking after every drop
  • If remain blue, no protein, if turn violet, got protein