Food Tests Lab Report Essay

798 Words Nov 12th, 2012 4 Pages
Food Test 1: Test for Glucose – with Benedicts solution
Benedicts solution is used to test for simple sugars, such as glucose. It is a clear blue solution of sodium and copper salts. In presence of simple sugars, the blue solution changes color to either green, yellow or brick-red, depending on the amount of sugar.

Method
1) Mix smalls amount of each food sample (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes with distilled water to make a liquid test. Take another test tube with glucose solution to act as a control so as to compare the difference in color after the completion of the experiment.
2) Label each of the test tubes with a marker for the substance.
3) Add 10 drops of
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More accurately, it detects the presence of peptide bonds. Peptide bonds form a violet chelate complex with copper (II) ions present in the Biuret Reagent.

Method
1) Mix smalls amount of each food samples (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes with distilled water to make a liquid test. Take another test tube with protein solution to act as a control to compare the difference in color after the completion of the experiment.
2) Label each test tube with a marker for the substance.
3) Add 5 drops of Biuret reagent solution to each test tube. Shake gently to mix.
4) Note any color change.

Positive test for proteins: the solution will turn from blue to pink/purple.

Food Test 4: Test for Lipids – the ethanol emulsion test.
Ethanol determines the presence of lipids – i.e., fats and oils. The solubilities of lipid in ethanol and water are exploited in this test since lipids are soluble in ethanol but not in water. So, if lipids are present a milky/cloudy white suspension is formed.

Method
1) Add all different food samples (i.e., Egg lumen, cylindrical piece of potato tuber, bread crump and crisps) in different test tubes. Also, take another test tube with Vegetable oil to act as a control to compare the difference in emulsion of the lipids after the completion of the experiment.
2) Label each test tube

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