Maltose

Maltose is a disaccharide made up of two glucoses joined by an alpha(1→4) glycosidic bond. It is also known as maltobiose and as malt sugar, since it appears in germinated barley grains. It is found in products such as beer and others, and can be obtained by hydrolysis of starch and glycogen. Provides a very high glycemic load.

Structure

Its formula is C₁₂H₂₂O₁₁. The bond between the two glucose molecules is established between the oxygen of the anomeric carbon (from -OH) of one glucose and the oxygen attached to the fourth carbon of the other. Its full name is therefore α-D-glucopyranosyl-(1→4)-D-glucopyranose. When this union occurs, a water molecule is released and both glucose molecules are linked by an oxygen that acts as a bridge (glycosidic bond).

Maltose presents the free hemiacetal OH (in the second glucose) so it is a reducing sugar that gives the Maillard reaction and the Benedict reaction.

History

Maltose sap.

The maltose was discovered by the Irishman Cornelius O'Sullivan in 1872 and its name comes from malt, from the Old English mealt and the suffix - osa, a suffix that forms names of sugars and other carbohydrates.