Practical Biochemistry Tests

Practical Biochemistry Tests

STARCH:

• Add a solution of iodine to sample
• If starch is present, iodine changes colour from yellow-brown to blue-black

REDUCING SUGARS:

• Add Benedicts solution (alkaline copper sulphate) to sample
• Heat in a water bath of 80^oc
• If reducing sugar is present it turns brick-red – if not present no change
• Compare sample to know sugar contents in a colorimeter
• If not present – do non-reducing sugar test
• If present – compare on a graph to the know sugar contents solutions

NON-REDUCING SUGARS:

• Make sure no reducing sugars in sample
• Boil the sample with Hydrochloric acid
• Cool solution and neutralise by adding sodium hydrogen carbonate solution
• Repeat reducing sugar test again

BIURET TEST (TESTING FOR PROTEINS):

• Add biuret reagent to sample
• If colour changes to lilac proteins are present

ETHANOL EMULSION TEST (TESTING FOR LIPIDS):

• Mix sample with ethanol – dissolves any present lipid
• Then pour liquid into water contained in another clean test tube
• If lipid present – cloudy white emulsion with form near top of water