Disaccharide

Sucrose, a common disaccharide

A disaccharide is a sugar (a carbohydrate) composed of two monosaccharides, such as glucose and fructose that make up the disaccharide sucrose. It is formed when two sugars are joined together and a molecule of water is removed. Due to this, disaccharides cannot hydrolyse, meaning their molecules are unable to be broken down through a reaction with water. For example, milk sugar (lactose) is made from glucose and galactose whereas cane sugar (sucrose) is made from glucose and fructose.

Common disaccharides

Disaccharide Unit 1 Unit 2 Bond Notes
Sucrose (table sugar, cane sugar, saccharose, or beet sugar) glucose fructose α(1→2) Sucrose is found naturally in many food plants.
Lactose (milk sugar) galactose glucose β(1→4) Lactose is found in milk products.
Maltose glucose glucose α(1→4) Produced during the malting of barley
Trehalose glucose glucose α(1→1)α Present in fungi and insects. Successfully produced at an industrial scale by enzymatic treatment of starch for use as a food ingredient.
Cellobiose glucose glucose β(1→4) -

Maltose and cellobiose are hydrolysis products of the polysaccharides, starch and cellulose, respectively. Some common Disaccharides are: Maltose, Lactose and Sucrose.