Lab Report Procedure 6. 1: Perform Benedict’s test for reducing sugars. Introduction: Benedict’s tests allows for the detection of the presence of reducing sugars. All monosaccharides are reducing sugars since all of them have active carbonyl group. Some disaccharides that are exposed to a carbonyl group are also reducing sugars but less reactive than monosaccharides. By mixing the sugar solution with Benedict’s solution and heating them, a redox reaction will occur.
The copper (II) sulphate present in Benedict’s solution reacts with electrons from aldehyde or ketose group of reducing sugars to form cuprous oxide, a red brown precipitate. Materials: The materials used in order to detect starches was: test tubes, distilled water, Benedict’s solution, starch were used. Negative Control: H20 Positive Control: Starch Obtain nine test tubes and number them 1-9 Add to each tube the materials to be tested. Add 2ml of Benedict’s solution to each tube.
Place all the tubes in boiling water- bath for 3 minutes and observe color changes during this time. After 3 minutes , remove the tubes from the water- bath and give the tubes ample time to cool to room temperature. Record the color of their contents. Procedure 6. 2: Perform the iodine test for starch Tube Solution Benedict’s Color Reaction Iodine Color Reaction 1 10 drops onion juice No change Blue->Black w/white No change 2 10 drops potato juice Precipitation Yellow-> blue 3 10 drops sucrose solution
No change No change 5 10 drops distilled water No change No change 6 10 drops reducing sugar solution Blue No change 7 10 drops starch solution No change Yellow-> Blue 8 Unknown Blue-> Red Brown 9 Unknown 2 Blue Brown 4 10 drops glucose solution Blue-> Brown No change Tube Solution Color 1 2 ml egg albumen Green/yellow 2 2 ml honey No change 3 2ml amino acid solution Purple 4 2ml distilled water No change 5 2ml protein solution Purple 6 Unknown Colorless 7 Unknown 2 Colorless