Determination of Redusing Sugar Using Dns Method Essay

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Pages: 12

1.0 ABSTRACT The production of reducing sugars by acid of carbohydrate cereals powder, jams (total sugar content) and jams (reducing sugar content) were performed in order to study reducing sugar production. The study involved hydrolysis carbohydrate cereals powder and jams by immersing in boiling water at environmental temperature. Acid hydrolysis was carried out through reflux boiling for 20 minutes with 10ml 0f 1.5M concentrations of diluted sulphuric acid. Reducing sugars concentrations were determined by spectrophotometry using the 3, 5 dinitrosalicylic acid (DNS) method. The first sample was operated as blank for zero. The stock solution was prepared in order to find the unknown concentration of carbohydrate cereals …show more content…
following exactly the same procedures for the actual samples. When the effects of extraneous compounds are not known, one can effectively include a so-called internal standard by first fully developing the color for the unknown sample; then, a known amount of sugar is added to this sample. The increase in the absorbance upon the second color development is equivalent to the incremental amount of sugar added.
The concentration of the colored complex can be determined with the spectrophotometer set at 540nm.The sugar concentration of unknown sample can then be read off a calibration curve (standard curve) created using known sugar concentrations. The dilutions of a solution of known concentration are used to determine the concentration of unknown.

The figure illustrating how glucose react with DNS (Dinitrosalicylic acid) to give 3-amino-5-nitrosalicylic acid (red-brown) which is detected in spectrophotometer. The background information about the nature of sugar is very essential. This method detects glucose, fructose and other monosaccharide only. Sucrose cannot be detected by this method directly. Therefore, the sample containing sucrose must be digested so that glucose and fructose products can be detected; (Lanthong et