XII.WEEK
12th WEEK
Reduction of carbohydrates; picric acid test, qualitative benedict test
Test observations and results report
It is the oxidation reaction of the anomeric
carbon of the monosaccharides containing
free semi acetal hydroxyls to the carboxylic
acid.
During this reaction, the sugar acts as a
reducing agent; Ag2 + removes ions such as
Hg2 +, Bi3 +, Cu2 +; such sugars are defined
as reducing sugars.
Reductive sugar is a type of sugar that forms
aldehyde or ketone in basic solution. Such
sugars, for example, act as reductants in the
Maillard reaction or the Benedict reaction.
Reducing sugars include fructose, glucose,
lactose, arabinose, and maltose.The ketose
monosaccharides, which are ketone groups,
and the aldehydic group are called
aldoses. Sucrose is not a reducing sugar.
Picric acid experiment
This test is based on the conversion of reducing sugars to colored picric acid.
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Qualitative Benedict ezperiment
It is understood by the Benedict assay whether the solution known to be a carbohydrate is reductive. With this experiment, the presence of sugar in the urine can be determined and its concentration can be determined semiquantitatively.
Carbohydrates bearing the free aldehyde or ketone group (carboxyl group) reduce the copper ions from + 2 to + 1 due to the effect of heat in the alkaline environment and discoloration is observed. Because all of the monosaccharides have a free carbonyl group, they give a positive result in this experiment.
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