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The Benedict's Test

The function of this experiment was to use Iodine, Benedict and Biuret to check the reaction of the following 12 samples: 1% glucose, 0. 3% glucose-1-phosphate, 1% maltose, honey, 1% sucrose, 1%lactose, 1% glycogen, 1% starch, protein, beer, pure water and an unknown solution (test tube: 300). The iodine test for starch was to test how would starch responded if we put iodine in it. The color of starch before the test was clear. The color of the iodine was brown. When you added iodine into starch, the outcome was the starch service turned dark blue.

Starch had a positive result is due to the fact that of the complex of iodine stuck inside the amylase coil which produced a characteristic purple – black color (Elservier Science Publishers, 1988). Likewise, starch was composed of polymers of glucose and long direct chains were amylase (Alberts Bray, Hopkin Johnson, Lewis Raff, Roberts Walter, 2009). The Benedict’s test for minimizing sugars was used to determine the presence of lowering sugars. The color of the samples before was clear.

The color of the Benedict was blue.

When you included Benedict into the samples and heated it up in the warm water bath for around 5 minutes. The aldehyde practical group was the lowering representative in minimizing sugars and they all had a favorable result was since of their capability to serve as a minimizing agent throughout the Benedict’s test. A lowering representative donated electrons during a redox reaction and was itself oxidized. Lowering sugars had either an aldehyde practical group or have ketone group– in an open chain kind– which can be converted into aldehyde (Sur, B.

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K., R. K. Shukla, and V. S Agashe, 1972). The Biuret test for protein was used to identify the presence of peptide bonds in proteins. The color of samples before was clear. Both salt hydroxide and copper sulfate were clear color as well. When you included sodium hydroxide and copper sulfate into the samples, protein would become purple. The structure of proteins was type by the peptide bond, which was discovered between the carboxyl and amino group of 2 adjacent amino acid residues (Alberts Bray, Hopkin Johnson, Lewis Raff, Roberts Walter, 2009).

When peptide bonds were presented in an alkaline solution, the copper (II) ions would form a coordinated with four nitrogen atoms involved in peptide bonds. Copper sulfate solution was a blue color, but when the copper (II) ions were coordinated with the nitrogen atoms of these peptide binds, the color of the solution changes from blue to violet. The color changed was dependent on the number of peptide binds in the solution, so the more protein, the more intense the changed would be (American Chemical Society, 2000).

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The Benedict's Test. (2016, Jul 16). Retrieved from

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