B 3.3 The Chemistry Of Food

Question 1

How do you prepare a food sample?

Answer 1

First, get a piece of food and break it up using a pestle and mortar.

Then transfer the ground up food to a beaker and add some distilled water.

Next give the mixture a good stir with a glass rod to dissolve some of the food.

Finally, filter the solution using a funnel lined with filter paper to get rid of the solid bits of food.

Question 2

What method do you use to test for sugars. What type of sugar are you testing for and describe the steps.

Answer 2

You use the Benedict’s test, which tests for reducing sugars

Prepare a food sample and transfer 5cm3 to a test tube.

Prepare a water bath so that it’s set to 75C.

Add some Benedict’s solution to the test tube (about 10 drops) using a pipette.

Place the test tube in the water bath using a test tube holder and leave it in there for five minutes. Make sure the tube is pointing away from you.

If the food sample contains a reducing sugar, the solution in the test tube will change from the normal blue colour to green, yellow or brick-red- it depends on how much sugar is i the blood.