Food tests

When testing for protein, what reagent did you use?

Biuret reagent

What colour indicates the presence of protein in a food sample?

Purple

What was our control and test for the protein experiment

Into our control we place a volume of distilled water.

Into our test tube we place the same volume of milk.

What colour indicates no protein is present?

The test tube will remain that transparent blueish colour.

What do we use to test for reducing sugars?

Benedict’s solution

Give examples of reducing sugars

Glucose, fructose, galactose etc.

Give example of a non-reducing sugar

Sucrose (disaccharide)

What was our control and test in the reducing sugar practical

In our control test tube place a volume of distilled water and in our actual test tube place an equal volume of glucose solution.

What do we do then with our 2 test tube (for reducing sugar experiment)

We heat them for 5 minutes in a hot water bath.

What colour change can noted with the glucose solution?

The glucose turns from blue to brick red, indicating it is a reducing sugar.

What chemical do we use when testing for starch?

Iodine solution

What was our test and control for starch experiment?

Our control was distilled water.

Our test was 1% starch solution.

We add a few drops of iodine to both solutions.

What will the colour changes in our starch experiment be?

• Our starch solution turns blue/ black in colour.

• The distilled water remains orange.

What is the other name for the test for lipids, apart from the brown paper test

The Sudan III test

What is the control and test for lipids?

Our control is distilled water.

Our test is lipids.

What do we add to the 2 sheets of brown paper?

To one sheet, we add 2 drops of water.

To the other we add 2 drops of oil.

We then allow both to dry.

What can you note on the piece of paper with the oil on it (after drying)?

A permanent transluscent stain