Food tests

Question 1

How to test for glucose?

Answer 1

GLucose test strips
- dip the test end of the strip into a sample.

The test end of Clinistix paper appears blue
-> The test end turns brown in the presence of glucose

Question 2

How to test for reducing sugars?

Answer 2

Benedict’s test
- Add 2cm^3 of Benedict’s solution to an equal volume of sample. Heat in a water bath for five minutes.

The benedict’s solution appears blue
-> A brick-red precipitate forms after heating with reducing sugars.

Question 3

How to test for starch?

Answer 3

Iodine test
- Add a few drops of iodine solution to the sample

The iodine solution appears brown
-> Iodine solution turns blue-black in the presence of starch

Question 4

How to test for lipids?

Answer 4

Grease spot test
- Add a drop of the sample to a piece of filter paper. Treat it with an organic solvent and observe it against light.

Oil forms a translucent spot on the filter paper, and the spot remains after drying
-> the oil spot disappears after a treatment with an organic solvents

Question 5

How to test for protiens?

Answer 5

Protein test strips
- dip the test end of the strip into a sample

The test end of Albustix paper appears yellow
-> The test end turns green

Question 6

How to test for vitamin?

Answer 6

DCPIP solution
- add the sample drop by drop to blue DCPIP solution and observe the colour changes

DCPIP solution appears blue
-> DCPIP solution is decolourized by vitamin C