Oligosaccharides are carbohydrates that yield two to ten monosaccharide units on hydrolysis. An example is maltotriose. They also serve as parts of blood group antigens.
As sucrose is a reducing sugar, it shows negative results to reducing tests. Sucrose is dextrorotatory (+66.5°) and its hydrolytic products are glucose and fructose. The rotation of fructose is laevorotatory (−92°), whereas that of glucose is dextrorotatory (+52.7°). The resulting product of hydrolysis shows laevorotation. This change from dextrorotation to laevorotation is known as…
It is composed of two molecules of monosaccharides, namely glucose and fructose. As both the functional groups (aldehyde and ketone groups) are involved in the formation of glycosidic linkage, there is no free reducing group. Hence, sucrose is known as a non-reducing sugar. The type of linkage in sucrose is α, β(1 → 2) glycosidic…
Sucrose is distributed in plants, particularly in sugarcane and sugar
Sucrose is distributed in plants, particularly in sugarcane and sugar beet.
It forms characteristic ball-shaped crystals with osazone reaction. The anomeric carbon of glucose is free and hence lactose is considered to be positive for all the reducing tests. Galactose is one of the components of lactose, which hence produces mucic acid on treating with concentrated HNO3.
It is composed of two monosaccharides, namely galactose and glucose molecules, linked by β(1 → 4) glycosidic linkage. The glycosidic linkage is between C-1 of β-galactose and C-4 of α-glucose (Figure 2.10). The anomeric carbon of glucose is free and hence lactose is considered to be a reducing disaccharide.
Occurrence Lactose is also known as milk sugar and is usually found in milk, occurring as β-lactose. This is produced in mammary glands.
It forms characteristic sunflower-shaped crystals with osazone reaction. The anomeric carbon of one glucose is free in maltose, and hence it possesses all the reducing properties of a reducing sugar. Isomaltose is also a reducing disaccharide. It consists of two molecules of glucose units. The type of linkage is α(1 → 4) glycosidic linkage. It…
It is composed of two molecules of glucose linked by α(1 → 4) linkage as shown in Figure 2.9. In the structure of maltose, the hydroxyl group on C-1 of the second sugar remains free, so it acts as a reducing disaccharide.