Identify the non reducing sugar among the given options.

CONCEPT:

Reducing and Non-Reducing Sugars

• Sugars are classified as reducing or non-reducing based on their ability to donate electrons to other molecules and become oxidized.
• Reducing sugars have a free aldehyde or ketone group that can be oxidized, while non-reducing sugars do not.

EXPLANATION:

• Glucose is a reducing sugar because it has a free aldehyde group.
• Fructose is a reducing sugar because it has a free ketone group.
• Lactose is a reducing sugar because it contains glucose and galactose units, both of which have free aldehyde groups.
• Sucrose is a non-reducing sugar because it does not have a free aldehyde or ketone group. The glycosidic bond between glucose and fructose in sucrose prevents the free aldehyde or ketone groups from being exposed.

Therefore, among the given options, sucrose is the non-reducing sugar.