Required Practical - Food Tests

Question 1

Test for starch

Answer 1

1 Place a small amount of food on the spotting tile.
2 Add a few drops of iodine solution to the food on the
spotting tile.
3 Yellow–red iodine solution turns blue–black if starch is
present.
4 Record your result in the results table.
5 Repeat steps 1–4 for other types of food.

Question 2

Test for lipids

Answer 2

1 Place a small amount of food into a test tube.
2 Add a few drops of ethanol to the test tube.
3 Shake the test tube and leave for 1 minute.
4 Pour the solution into a test tube of water.
5 Ethanol added to a solution gives a cloudy white layer if
a lipid is present.
6 Record your result in the results table.
7 Repeat steps 1–6 for other types of food.

Question 3

Test for protein

Answer 3

1 Place a small amount of food in a test tube.
2 Add 1 cm of Biuret reagent. Alternatively add 1 cm
sodium hydroxide solution and then add a few drops of
copper sulfate solution.
3 Blue Biuret reagent turns purple if a protein is present.
4 Record your result in the results table.
5 Repeat steps 1–4 for other types of food.

Question 4

Test for sugar

Answer 4

1 Place a small amount of food in a test tube.
2 Add enough Benedict’s solution to cover the food.
3 Place the test tube in a warm water bath for 10 minutes.
4 Blue Benedict’s solution turns brick red on heating if a
sugar such as glucose is present.
5 Record your result in the results table.
6 Repeat steps 1–5 for other types of food.