Which of the following is non-reducing disaccharide sugar?

Explanation

Mannose: Mannose is a monosaccharide, not a disaccharide. It is a single sugar unit and does not fit the criteria for a non-reducing disaccharide. Sucrose: The correct option is sucrose. Sucrose is a non-reducing disaccharide composed of one molecule of glucose and one molecule of fructose linked together by a glycosidic bond. It is commonly known as table sugar and is obtained from sugarcane or sugar beets. Sucrose is non-reducing because it lacks a free aldehyde or ketone group, which is required for a sugar to be considered reducing. Both glucose and fructose have their anomeric carbon involved in the glycosidic linkage, leaving no free aldehyde or ketone group to participate in a reducing reaction. Maltose: Maltose is a reducing disaccharide composed of two glucose molecules linked together by a glycosidic bond. It is formed during the breakdown of starch into smaller carbohydrate units. Maltose is reducing because one of its glucose units has a free aldehyde group on the anomeric carbon, which can participate in a reducing reaction. Lactose: Lactose is a reducing disaccharide composed of one molecule of glucose and one molecule of galactose linked together by a glycosidic bond. It is commonly known as milk sugar and is found in milk and dairy products. Lactose is reducing because the glucose unit in lactose has a free aldehyde group on the anomeric carbon, allowing it to participate in a reducing reaction.In summary, option b) Sucrose is the correct option. Sucrose is a non-reducing disaccharide composed of glucose and fructose, lacking a free aldehyde or ketone group necessary for a reducing reaction. The other options (a) Mannose, (c) Maltose, and (d) Lactose are all reducing disaccharides.