4th

Name: Geofrey Jinuin

Class: 3 Melati

Aim

: To test for starch, glucose, protein and fat.

Material

:1% starch solution, 10% glucose solution, 1% albumen solution, cooking oil, benedicts solution, iodine solution, millon’s reagent, ethanol, distilled water

Apparatus

:Dropper, test tube, beaker, tripod stand, wire gauze, Bunsen burner.

Method: a)

Iodine test for starch i. Pour 2cm of starch solution into a test tube. ii. Add 2 drops of iodine solution. Observe the colour change. b) Millon’s test for protein. i. Pour 2cm of starch solution into a test tube. ii. Add 2 drops of millon’s reagent to the albumen solution. iii. Heat the mixture in a water bath. Observe any changes in the mixture. c) Emulsion test for fat. i. Add 5 drops of ethanol into a test tube. ii. Add 2 drops of cooking oil into the same test tube. Shake the mixture in the test tube. iii. Add distilled water into the same test tube until it is half full and shake the mixture thoroughly. iv. The mixture is left to stand for 2 minutes, Result: Test Iodine test for starch Benedicts test for glucose. Millon’s test for proteins Emulsion test for fat.

The mixture turns blue- black The mixture turns brick red The mixture turns red on heating Emulsion formed at the upper layer

Starch is present Glucose is present Protein is present Fat is present

Question: 1. 2.

Why do you use a water bath to heat the mixture in the test tube in activity B? -Because the mixture in the test tube will spill out it heared on the Bunsen burner without water bath. Is cooking oil soluble in ethanol? -Yes, because ethanol soluble for oil.

Conclusion. -The food test for carbohydrates, proteins and fat are carries out using specific reagents or materials.