1.Find THE AMOUNT OF REDUCING SUGARS AND STARCH IN YELLOE AND GREEN BANANAS by Using the Benedict's test nad Iodine test. Why the Benedict's solution should be used in excess.

1077 WordsFeb 3, 20095 Pages
Tiltle: What was happened to the bananas? Objective: To compare the amount of reducing sugars and starch in yellow and green bananas. Introduction: Bananas are green in colour and taste flat but after they are harvested and stored for some days, they will turn yellow from green and become sweet. Hypothesis: The green banana tasted plain because it contained large amount of starch, while the yellow banana tasted sweet since it contained large amount of reducing sugars. Biological principles: Benedict's test for reducing sugar: Reducing sugars include all monosaccharides (glucose) and some disaccharides (maltose). Benedict's solution contains copper sulphates. Reducing sugars reduce copper(2) ions present in the blue copper sulphate…show more content…
In the Benedict's test, the volume of ppt in ripe banana sample is the largest, ppt in the raw banana is is the smallest, ppt in the half ripe banana is greater than the raw banana's but smaller than that of ripe banana. In the iodine test, the colour of the sample shows that the raw banana has the largest amount of starch. The raw banana has the smallest amount of starch. The amount of starch in half-ripe banana is greater than that of ripe banana but smaller than that of the raw banana. In the Benedict's test, we can use another means to show the result. After having a hot water bath,we can remove the liquid solution form the sample. Then we put it onto the water bath with evaporate dish in order to remove the water in the ppt. After that we weight the ppt. In the iodine test, the result is not accurate enough because the result is determined by our bear eye. We can use another method to show the result more accurately. First, we can use the colorimeter to determine the colour intensity of the blue colour of the sample. Second, we can use the same amount of sample and drop the iodine solution until their colour intensity are the same. At the same time, we can measure the drops of the iodine we have added. The larger amount of drops used that means more starch is present. The

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