food tests

Question 1

what’s the test for glucose

Answer 1

Benedict’s test

Question 2

Benedict’s test method:

Answer 2

1. put a small sample of food into a test tube
2. add 3cm^3 Benedict’s solution to the test tube
3. heat the contents of the test tube in a water bath at 85 degrees Celsius for 5 mins
4. brick red, orange, green - glucose is present

Question 3

what’s the test for starch

Answer 3

Iodine test

Question 4

Iodine test method:

Answer 4

1. put a small sample of food into separate depressions of a dropping tile
2. add 2-3 drops of iodine into each sample
3. blue/black colour - starch is present

Question 5

what’s the test for protein

Answer 5

Biuret’s test

Question 6

Biuret’s test method:

Answer 6

1. put a small sample of food into a test tube
2. add 2cm^3 of Biuret’s reagent into a test tube
3. purple - protein is present

Question 7

what’s the test for lipids

Answer 7

emulsion test

Question 8

emulsion test method:

Answer 8

1. add 2cm^3 ethanol to a small sample of ground up food in a test tube
2. shake well
3. all mixture to settle
4. gently add 4cm^3 of water by drops
5. white emulsion - lipids are present