Biochemical Food Tests Food tests for: Starch Reducing Sugar Non-reducing Sugar Protein Lipid 4.5 / 5 based on 4 ratings ? BiologyBiological molecules, organic chemistry and biochemistryASOCR Created by: Jonathan AdamsCreated on: 29-05-10 15:32 Starch Test Add a solution of Iodine (in potassium iodide solution) to the sample. If starch is present colour will change from yellow-brown to blue-black 1 of 5 Reducing Sugar Test Add Benedict's solution (alkaline copper sulphate) to the sample. Heat to 80C in a water bath. The solution will change from blue to an organge-red precipitate. 2 of 5 Non-reducing Sugar Test First if the test for a reducing sugar has came back negative (no colour change) Make sure there are no reducing sugars in the solution by boiling with hydrocholoric acid. Cool the solution and neutralise it by adding sodium hydrogencarbonate. Carry out the reducing sugar test again. If non-redcing sugars present the solution will change from blue to an organge-red precipitate 3 of 5 Protein Test Add Biuret reagent to sample. If proteins are present, the biuret will react with the peptide bonds found in the protein. The solution will change from blue to lilac. 4 of 5 Lipid Test Mix the sample with ethanol to dissolve the lipid present. Then pour the liquid (alcohol with dissolved fat) into water contained in another clean test tube. If lipid is present, a cloudy white emulsion will form near the top of the water. 5 of 5
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