How do you prepare a food sample for a food test?

  1. Grind up the food using a pestle and mortar.
  2. Add water and stir to dissolve the food.
  3. Filter the mixture to remove the lumps of food.
  4. The remaining solution can be used for testing.

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What do we call the test for reducing sugars (like glucose)?

Benedict's test is the test for reducing sugars.

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What do we call the test for starch?

The Iodine test is the test for starch.

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What do we call the test for proteins?

The Biuret test is the test for proteins.

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What are the two tests for lipids?

The two tests for lipids are:


1 The Emulsion test.

2 The Sudan III stain test.

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What are the steps for carrying out the Benedict's test?

  1. Add 10 drops of Benedict's solution to your food sample.
  2. Heat in a water bath at 75°C for 5 minutes.
  3. Look for a colour change.

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What colour change are you looking for in the Benedict's test?

A colour change from blue to green, orange, or brick red indicates reducing sugars are present. 

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How do you perform the test for starch? What colour change would you look for?

Take your food sample and add a few drops of iodine.


If starch is present it will change from browny-orange to blue-black. 

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How do you perform the test for proteins? What colour change would you look for?

Take your food sample and add an equal volume of Biuret solution.


If protein is present it will change from blue to purple. 

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How do you perform the test for lipids?


What change would you look for?

Use the emulsion test.


  1. Place food sample in a test tube.
  2. Add 2cm3 of ethanol.
  3. Shake.
  4. Add 2cm3 of distilled water.
  5. If a cloudy emulsion forms then lipid was present.

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