Question
Which one of the following is a non-reducing carbohydrate?
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Maltose
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Sucrose
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Lactose
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Ribose 5 - phosphate
Solution
B.
Sucrose
Sucrose is a disaccharide of glucose 8 fructose. It is a non- reducing sugar as it do not contain any free anomeric c arbon atom. Maltose is a disaccharide of 2 glucose units. Its first glucose residue cannot undergo oxidation, whereas, second residue can undergo oxidation because it has a reactive free anomeric carbon atom. Hence, it is a reducing sugar.
Lactose and ribose - 5- phosphate are also reducing in nature due to the presence of a free ketonic or aldehyde group.
