maltose,organic compound composed of twoglucose molecules linked together. Thecompound (C₁₂H₂₂O₁₁) is adisaccharide formed during the breakdown ofstarch. It occurs naturally in sprouted grains, such asbarley,corn (maize), andwheat, and is found in malted foods and beverages, particularlybeer, in which it isfermented byyeast to producealcohol.

The glucose units of maltose are linked by a glycosidic bond, the nature of which leaves one of the glucose molecules in maltose with a freealdehyde that readily gives upelectrons to other molecules. As a result, maltose is easily broken down, rendering it highly water soluble and only mildlysweet. These chemical features influence the physical properties of maltose-containing food products.

In particular, the free aldehyde group in maltose participates in the Maillard reaction, which takes place between glucose andamino acids. In maltose-containing foods, this reaction is responsible for producing theircharacteristic complex flavors and browning, such as the golden-brown color on the crust of breads and cakes. In products such as baked goods, candies, and syrups, maltose also helps create a smooth chewy texture. Particularly in baked goods, it can help with moisture retention and softness, and, in some food products, maltose acts as apreservative, because of its ability to attract and hold moisture.

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carbohydrate: Lactose and maltose

In beer brewing, maltose derived from malted barley is the mainsugar present in wort, the solute-richliquid produced in mashing. In some cases, maltose syrups derived from other sources of starch, including corn and wheat, may be used instead in wort. Regardless of the source, maltose generally accounts for about 50 percent of thecarbohydrate content in wort. Maltose in the wort is taken up by yeast cells duringfermentation, when it is metabolized into itsconstituent glucose units prior to the production of alcohol.

Maltose is broken down into glucose in thesmall intestine by theenzymemaltase,facilitating its absorption into the bloodstream. Similar to other sugars, it serves as a source of energy for the body, providing about fourcalories per gram. Because of efficient breakdown by maltase, maltose, in the form of maltodextrin, is sometimes incorporated into infant formula to aid inmilk digestion.