2.9 Food tests

Question 1

How do you test for glucose?

Answer 1

• Add Benedict solution to the food sample in a test tube
• Heat the test tube in a hot water bath for 5 mins
  -Take the test tube out of the water bath
• If glucose is present, the solution should go from blue to orange

Question 2

How do you test for starch using iodine solution?

Answer 2

-Add drops of iodine into the food sample
-If starch is present, the solution should go from orange to black

Question 3

How do you test for protein?

Answer 3

-Add biuret solution into the food sample
- If protein is present, the solution should go from blue to purple

Question 4

How do you test for lipids?

Answer 4

-Mix the food sample with 4cm^3 of ethanol and shake
-Give time for the food sample to dissolve in the ethanol
-Strain the ethanol solution into another test tube
-Add the strained ethanol to an equal volume of cold distilled water (4cm^3)
-If lipids are present, a cloudy emulsion should be formed