The document describes procedures for testing foods for the presence of starch, glucose, proteins, and oils/fats. For each test, it provides the steps to perform the test along with the expected color change results for a positive or negative indication of the substance being tested. The tests involve adding reagents like iodine, Benedict's solution, Biuret reagent, or water and observing any color changes that confirm or rule out the presence of starch, glucose, proteins, or oils/fats.

1. Food Tests

2. Test for StarchPlace a little starch powder in a depression on a spotting tile.Add a few drops of iodine.Positive Result : Blue/Black colourNegative results: Browncolour

3. Test for GlucoseTake 10ml of glucose solution in a test tube.Add 5 drops of Benedict’s solution to the test tube.Lower the test tube into a water bath kept at 70oC.

4. Test for GlucoseStrong Positive Result : Brick Red precipitateMedium Positive ResultYellow orange precipitateWeak ResultGreen colourNegative results: Blue colour

5. Test for proteinsDissolve a little milk powder in a test tube.Add a few drops of Biuret reagentPositive Result : Purple ColourNegative results: Blue colour

6. Test for oil and fatPlace about 1cm3 of ethanol in a test tube.Add a few drops of oil and mix by shaking.Add an equal amount of water and shake again.Positive Result : A cloudy emulsion formsNegative results: Liquid remains clearNoteFood with solid fats can be tested by crushing them in ethanol.