Food Samples and Food Tests

Question 1

How should you prepare a liquid food sample?

Answer 1

1. Take a piece of food and break it up, using a pestle and mortar.
2. Transfer the ground food to a beaker, and add distilled water.
3. Stir the mixture with a glass rod in order to dissolve the food.
4. Finally, filter the solution using a funnel lined with filter paper.

Question 2

How should you test for glucose in a food sample

Answer 2

1. Transfer a liquid food sample into a test tube.
2. Place this tube into a hot water bath set to 70 degrees Celsius.
3. Use a pipette to add Benedicts solution to the test tube.
4. Leave for five minutes. If the sample contains a low concentration of glucose, it will become green-yellow; if it contains a high concentration, it will become red.

Question 3

How should you test for starch in a food sample?

Answer 3

1. Transfer a liquid food sample into a test tube.
2. Use a pipette to add iodine solution to the tube.
3. Gently shake the test tube. If the sample contains starch, it will become blue-black.

Question 4

How should you test for protein in a food sample?

Answer 4

1. Transfer a liquid food sample into a test tube.
2. Use a pipette to add Biuret solution to the tube.
3. Gently shake the test tube. If the sample contains protein, it will become pink-purple.

Question 5

How should you test for lipids in a food sample?

Answer 5

1. Transfer a liquid food sample into a test tube.
2. Use a pipette to add ethanol to the tube.
3. Add water, then gently shake the test tube. If the sample contains lipids, it will become milky white.