Question

What are reducing and non reducing sugar?

Answer 1

Non-reducing sugars do not have an OH group attached to the anomeric carbon so they cannot reduce other compounds. All monosaccharides such as glucose are reducing sugars. A disaccharide can be a reducing sugar or a non-reducing sugar. Maltose and lactose are reducing sugars, while sucrose is a non-reducing sugar.

Answer 2

Answer:

Reducing Sugars:  

 These sugars have free aldose and ketose group.

 These reduce Cu2+ (Cupric ion) to Cu+ (Cuprous ion) present in Benedict's solution or Fehling's solution.

 Benedict's solution contains blue coloured alkaline solution of copper (Cupric) sulphate.

 Reducing sugar changes it into insoluble reddish cuprous oxide on gentle heating.

 All monosaccharides, lactose and maltose are reducing sugars.

 Sucrose is non-reducing sugar because it does not have free aldose or ketose group. Aldose group of glucose and ketose group of fructose are lost due to formation of glycosidic bond between them.

Note:  The reaction is used for detecting glucose in urine.

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