Principles of Biochemistry

A disaccharide is a carbohydrate that contains two molecules of monosaccharide units covalently  bonded to each other. Examples: Maltose, lactose and sucrose.

On hydrolysis, maltose yields two molecules of glucose, lactose yields one molecule of galactose and one molecule of glucose,  and sucrose yields one molecule of glucose and one molecule of fructose. Maltose is formed when starchy material is hydrolysed. Sucrose is present in fruit juices, sugarcane and sugar beet. Lactose is the principal sugar present in milk.