Sucrose: Sucrose occurs in large amounts in sugarcane, palm juice (palm sugar) and beet root (beet sugar). It occurs along with glucose and fructose in several fruits. On hydrolysis, it gives a mixture of glucose and fructose known as invert sugar.
Lactose: It occurs in human milk (7 %) and in the milk of other animals (mammals) (Cow’s milk and buffalo’s milk 4 %). It is formed by the combination of one molecule each of glucose and galactose in the mammary gland. Lactose is hydrolysed in digestive tract into glucose and galactose.
Maltose: This occurs in malt prepared from germinated cereal grains. On hydrolyses it gives two molecules of glucose.