Question

Maltose is a reducing sugar, whereas sucrose is a non-reducing sugar.
A) True
B) False

Answer 1

Hint: Reducing sugar is capable of acting as a reducing agent as it has a free aldehyde group or a free ketone group. All monosaccharides, some disaccharides, some oligosaccharides, some polysaccharides are reducing sugars. Non-reducing sugar doesn't contain an OH group attached to anomeric carbon and can’t reduce other compounds.

Complete Answer:
Maltose (malt sugar) is a reducing disaccharide while sucrose is a non-reducing one because of the absence of free aldehyde or ketone group in sucrose.
In maltose, there are two glucose present. The glycosidic oxygen atom of one glucose is alpha and bonded to C-4 atom of another glucose unit which is aglycone.
Reducing sugar have only one of their two anomeric carbons are involved in making bond and the other is free which can convert to open chain form with an aldehydic group. So, this aldehydic group allows the sugar to act as reducing sugar.
Sucrose is commonly found in the form of white sugar and consists of monosaccharide glucose and fructose.
In sucrose the two monosaccharide units are held together by a glycosidic linkage between C-1 of alpha glucose and C-2 of beta fructose.

The given statement is True.

Additional information:

Sl.No	SUCROSE	MALTOSE
1.	It is found in plants like cane and beet sugar.	It is found in potatoes, sweet potatoes, soybeans.

Note: Maltose and sucrose are the forms of sugars called Disaccharides. Maltose is an important intermediate in digestion of starch.