Food tests

What color change indicates the presence of starch when using the iodine test?

• Orange to green

• Orange to blue-black

• Blue to purple

• Colorless to pink

Which color change indicates a positive result for the presence of proteins using the Biuret test?

• Blue to green

• Blue to purple/lilac

• Orange to blue-black

• Colorless to yellow

What is the correct procedure for performing Benedict's test for reducing sugars?

• Add Benedict's reagent, then shake vigorously.

• Add Benedict's reagent, then heat in a water bath.

• Add Benedict's reagent, then add distilled water.

• Add Benedict's reagent, then add ethanol.

What is the positive result for the ethanol emulsion test for fats?

• A blue-black color

• A purple/lilac color

• A white emulsion

• A brick red precipitate

What colour does the DCPIP turn if vitamin C is present?

• Blue

• Black

• Colourless

• Purple