Testing Foods

Question 1

Name two reducing sugars and one non-reducing sugar

Answer 1

Glucose and fructose

Sucrose

Question 2

How do you test for reducing sugars?

Answer 2

Add an equal volume of Benedict’s solution to a food solution and mix. Then heat the mixture in a hot water bath for a few minutes. If reducing sugars are present the solution will turn green/orange/red

Question 3

What do reducing sugars cause?

Answer 3

A reduction reaction with the reagent

Question 4

How do you test for fats?

Answer 4

Ethanol emulsion test:
Add an equal volume of ethanol to the solution and shake. Add water to mixture. If fats are present, the mixture will turn cloudy

Question 5

How do you test for proteins?

Answer 5

Biuret test:
Mix food solution with potassium hydroxide. Then add copper sulfate solution and mix. If proteins are present, solution will turn a pale purple

Question 6

How do you test for starch?

Answer 6

Add a few drops of iodine solution to the food. If starch is present, it will turn a blue/black