1. Lactose is a disaccharide found in milk of mammals and hence it is referred to as milk sugar.
2. On hydrolysis, it yeilds galactose and glucose. The β – D galactose and β – D glucose are linked by β – 1, 4 – glycosidic bond. the aldehyde carbon is not involved in the glycosidic linkage. Hence it retains its reducing property and is called a reducing sugar.