FOOD TESTS EDEXCEL IGCSE BIOLOGY

What is the test for glucose?

Benedict's

Give the method for the test for glucose and why?

Prepare a food sample and transfer 5cm3 to a test tube, prepare a water bath at 75*c, add Benedict's solution, place the test tube in the water bath for 5 minutes

Activation energy

What colour does the solution turn if it contains glucose?

Blue to green/yellow/brick-red

What is the test for starch?

Iodine

Give the method to test for starch

Make a food sample and transfer 5cm3 to a test tube, add a few drops of iodine and gently shake

What is the colour change for the presence of starch?

Brown-orange to black/blue-black

What is the test for proteins?

Biuret

Give the method to test for proteins

Prepare a food sample and transfer 2cm3 to test tube, add 2cm3 of Biuret's to the sample and gently shake,

What is the colour change for the presence of protein?

Blue to pink/purple

What is the test for lipids?

Sudan III

Give the method to test for lipids

Prepare a food sample and transfer 5cm3 to test tube, add 3 drops of Sudan III and gently shake

State the observation for the presence of lipids

The mixture seperates out into two layers, the top layer bright red