Food test review

Food Tests

Testing for Starch

• Add food sample to spotting tile.
• Add a couple of drops of iodine.
• If it turns blue or black, starch is present.

Testing for Sugar

• Add approximately 10 drops (2ml) of Benedict’s reagent to test tube.
• Heat solution in a water bath for 3-5 minutes.
• Observe for color change.

Testing for Protein

• Add a few drops of biuret A.
• Then add a few drops of biuret B.
• If it turns purple, protein is present.

Testing for Fat (Ethanol Method)

• Add the food and ethanol to a test tube; put a bung on the tube and mix.
• Pour the ethanol solution into a test tube of water; if fat is present, a layer forms at the surface. Crush solid foods before testing.

Testing for Fat (Paper Method)

• Take a piece of the food and rub it on the paper.
• If light passes through the paper, fat is present.

Reagents for Nutrient Tests

• Starch: Iodine
• Sugar: Benedict's solution
• Protein: Biuret reagent
• Fat: Ethanol or Greaseproof paper

Importance of Food Labels

• The FSA (Food Standards Agency) tests food to ensure food labels are correct.
• Nutritional labels on food are important for informing consumers about the nutrients in food.