Question

An example of non-reducing sugar is

• A. Glucose
• B. Sucrose
• C. Lactose
• D. Maltose

Hint:

All common monosaccharides are reducing. Among disaccharides, sucrose is the most notable non-reducing example.

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Reducing sugars have a free aldehydic or ketonic group (in the form of hemiacetal or hemiketal) that can reduce Tollen's reagent or Fehling's solution.
Step 2: Detailed Explanation:
1. Glucose is a monosaccharide and exists as a cyclic hemiacetal; it is a reducing sugar.
2. Maltose and Lactose are disaccharides with a free hemiacetal group in one of the sugar rings, making them reducing sugars.
3. Sucrose is a disaccharide where the glycosidic linkage is formed between the C1 of glucose and the C2 of fructose. Both the reducing groups (aldehyde of glucose and ketone of fructose) are involved in the bond formation.
Thus, sucrose has no free reducing group and is a non-reducing sugar.
Step 3: Final Answer:
Sucrose is the non-reducing sugar.