What are reducing sugars ?

Explanation

Reducing sugars are those which can act as reducing agents. They contain in the them a reducing group which may be aldehydic (-CHO) or ketonic (gt C = O) group. The characterictic reactions of reducing sugars are with Tollen's reagent and Fehling solution. Non-reducing sugars donot give these reactions. For example, glucose, fructose, lactose etc. are reducing sugars. Sucrose is regarded as a non-reducing sugar because both glucose and fructose are linked through their aldehydic and and ketonic groups by glycosidic linkage. Since these groups are not free, sucrose is a non-redicing sugar.