Q8 Food Tests

Question 1

Conduct a qualitative test for STARCH

Answer 1

Method: Add a few drops of iodine solution to the food sample (e.g. potato).
Result:
• Positive: turns blue-black
• Control with water: stays yellow-brown

Question 2

Conduct a qualitative test for FAT

Answer 2

Method: Drop or rub food sample onto brown paper. Allow to dry.
Result:
• Positive: a translucent spot remains after drying
• Negative: no translucent spot after drying

Question 3

Conduct a qualitative test for REDUCING SUGAR

Answer 3

Method: Add an equal volume of Benedict’s reagent to food solution (e.g. glucose). Heat at 60°C in water bath for 10 minutes.
Result:
• Positive: Blue to brick-red
• Control: Water stays blue

Question 4

Conduct a qualitative test for PROTEIN

Answer 4

Method: Add equal volume of Biuret reagent (sodium hydroxide and copper sulphate) to a food solution (e.g., milk).
Result:
• Positive: Blue turns purple
• Negative: Control with water stays blue