Sucrose is non-reducing sugar due to the linkage between both the anomeric carbon atoms.
Non-reducing sugars do not have a free ketone or aldehyde group. These sugars have acetal in place of hemiacetal. An acetal consists of two O-R group, one -R and -H group respectively. All these groups are attached to the same carbon.
Sucrose is a non-reducing sugar because
- The two monosaccharide units are held together by a glycosidic linkage between C1 of α-glucose and C2 of β-fructose. Since the reducing groups of glucose and fructose are involved in glycosidic bond formation, sucrose is a non-reducing sugar.
- Anomeric carbon of both the monosaccharides are involved in glycoside or acetal formation. So it does not have a free -CHO group