Biochemical Food Tests

Question 1

Describe the test for reducing-sugar’s.

Answer 1

1. Add Benedict’s reagent
2. Heat for 5 mins

+ve result turns from blue to red

Question 2

Describe the test for nonreducing-sugar’s.

Answer 2

1. Add Benedict’s reagent and heat to confirm -ve result
2. Add acid then heat
3. Add an alkali to neutralise the acid
4. Add Benedict’s reagent and heat

+ve result turns from blue to red

Question 3

Describe the test for starch.

Answer 3

1. Add a few drops of iodine

+ve result turns from orange/yellow to blue/black

Question 4

Describe the test for proteins.

Answer 4

1. Add a few drops of copper sulfate
2. Add a few drops of sodium hydroxide

+ve result turns from blue to purple

Question 5

Describe the test for lipids.

Answer 5

1. Add ethanol then add water
2. And shake

+ve result turns from clear to milky white emulsion