2.9: Practical: Investigate Food Samples for the Presence of Glucose, Starch, Protein and Fat

TEST FOR GLUCOSE:

TEST FOR GLUCOSE

Diagram Showing the Test for Glucose using Benedict’s Solution

METHOD: Add a few drops of Benedict's solution into test tube of test solution Heat test tube placed in a water bath set at 60 - 70 °C for 5 minutes Remove test tube from water bath and observe colour change

RESULT: If Glucose is present, solution will turn brick red If Glucose is not present, solution will stay blue

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TEST FOR STARCH:

TEST FOR STARCH

Diagram Showing the Test for Starch using Iodine Solution

METHOD: Use pipette to transfer sample solution into wells on tile Add a few drops of Iodine solution and observe colour change

RESULT: If Starch is present, solution will turn blue-black If Starch is not present, solution will stay brown

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TEST FOR PROTEIN:

TEST FOR PROTEIN

Diagram showing the Test for Protein

METHOD: Add a few drops of Biuret solution into test tube of sample solution Observe colour change

RESULT: If Protein is present, solution will turn violet If Protein is not present, solution will stay blue

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TEST FOR FAT:

TEST FOR FAT

Diagram showing the Test for Fats

METHOD: Test tube of sample solution is mixed with 2cm3 of Ethanol and 2cm3 of distilled water Observe colour change

RESULT: If Fat is present, a milky - white emulsion will form If Fat is not present, solution will remain colourless