Starch, the main storage polysaccharide in plants, consists of two components: amylose (15-20%) and amylopectin (80-85%). Amylose is a water-soluble, unbranched chain polymer of a-D-glucose units linked by C₁– C₄ glycosidic linkage.

Polysaccharides primarily serve as food storage or structural materials. They are commonly encountered in nature due to their abundance and diverse roles.

Lactose, known as milk sugar, consists of b-D-galactose and b-D-glucose units with a linkage between C₁ of galactose and C₄ of glucose. Lactose exhibits reducing properties as a free aldehyde group may be produced at C-1 of the glucose unit.

Maltose is composed of two a-D-glucose units, linked from C₁ of one glucose to C₄ of another. It shows reducing properties due to the free aldehyde group produced at C₁ of the second glucose unit.

Sucrose is dextrorotatory, but its hydrolysis produces dextrorotatory glucose and laevorotatory fructose. The mixture, known as invert sugar, is laevorotatory due to fructose’s higher laevorotation.