Required practicle 4 - Food tests

Question 1

What is required for all food tests?

Answer 1

• Grind food sample with water to make paste
• Transfer to beaker, add more distilled water and stir so food dissolves

Question 2

What is the test for starch?

Answer 2

• Add iodine
• Turns from orange to blue/black if present

Question 3

What is the test for glucose?

Answer 3

• Add 2cm^3 sugar solution and10 drops benedicts solution
• Place test tube in beaker half-filled with boiling water and leave for around 5 minutes
• If present turns from blue to green/yellow/brick-red depending on amount present

Question 4

What is the test for protein?

Answer 4

• Add biuret solution
• If present turns from blue to purple/lilac

Question 5

What is the test for lipids?

Answer 5

• dont filter solution as lipid molecules can get stuck to filter paper
• add few drops of distilled water and ethanol then gently shake
• If present solution forms white cloudy emulsion

Question 6

What is a hazard when testing for lipids?

Answer 6

• Ethanol is highly flammable
• So ensure no naked flames are present