Question

In disaccharides, if the reducing groups of monosaccharides i.e., aldehydic or ketonic groups are bonded, these are non-reducing sugars. Which of the following disaccharide is a non-reducing sugar?

• A.
• B.
• C.
• D.

Answer 1

The correct option is B

Reducing Sugar: Any carbohydrate whose structure contains an aldehydic or hemiacetal group is a reducing sugar. This free aldehydic or hemiacetal group can be easily oxidised accompanying the reduction of oxidising agent.


In option (B), the aldehyde group of glucose and keto group of fructose are involved in the glycosidic linkage.

So, this sugar lacks free aldehyde or hemiacetal group.

Therefore, this is a non-reducing sugar whereas options (A), (C) and (D) have free hemiacetal groups. So, they are reducing sugars.

So, the correct answer is option (B).