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(môl`tōs) or

malt sugar,

crystalline disaccharide (see carbohydratecarbohydrate,
any member of a large class of chemical compounds that includes sugars, starches, cellulose, and related compounds. These compounds are produced naturally by green plants from carbon dioxide and water (see photosynthesis).
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). It has the same empirical formula (C12H22O11) as sucrose and lactose but differs from both in structure (see isomerisomer
, in chemistry, one of two or more compounds having the same molecular formula but different structures (arrangements of atoms in the molecule). Isomerism is the occurrence of such compounds. Isomerism was first recognized by J. J. Berzelius in 1827.
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). Maltose is produced from starch by hydrolysis in the presence of diastase, an enzymeenzyme,
biological catalyst. The term enzyme comes from zymosis, the Greek word for fermentation, a process accomplished by yeast cells and long known to the brewing industry, which occupied the attention of many 19th-century chemists.
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 present in malt. Maltose is hydrolyzed to glucoseglucose,
or grape sugar,
monosaccharide sugar with the empirical formula C6H12O6 . This carbohydrate occurs in the sap of most plants and in the juice of grapes and other fruits.
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 by maltase, an enzyme present in yeast; the glucose thus formed may be fermented by another enzyme in yeast to produce ethanolethanol
or ethyl alcohol,
CH3CH2OH, a colorless liquid with characteristic odor and taste; commonly called grain alcohol or simply alcohol. Properties

Ethanol is a monohydric primary alcohol. It melts at −117.
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. Maltose is important in the brewing of beer. It is an easily digested food.


An oligosaccharide, known as malt sugar, a reducing disaccharide (see illustration). It is fermentable by yeast in the presence of d -glucose.

Formula for maltose (α form; * indicates reducing group)enlarge picture
Formula for maltose (α form; * indicates reducing group)

The action of animal (salivary and pancreatic) as well as plant (germinating cereals, sweet potato) amylases on starch, dextrin, and glycogen produces maltose as the main end product. Maltose is hydrolyzed by acids and the enzyme maltase to two molecules of d -glucose. See Glucose, Maltase, Oligosaccharide



a natural disaccharide, consisting of two glucose radicals. Large quantities of maltose are present in germinated grains of barley (malt), rye, and other cereals; it is also found in tomato plants, as well as in the pollen and nectar of several plant species.

Maltose is readily soluble in water and has a sweet taste; it is a reducing sugar, since it contains an unsubstituted hemiacetal hydroxyl group. The biosynthesis of maltose from β-Dglucopyranosyl phosphate and D-glucose is known to occur only in certain species of bacteria. In animal and plant organisms, maltose is formed upon enzymatic splitting of starch and glycogen. Maltose is decomposed into two glucose radicals by the action of the enzyme a-glucosidase (maltase), which is present in the digestive juices of animals and humans, germinated grains, saprophytic fungi, and yeast.

Genetically determined absence of maltase in the intestinal mucosa of humans leads to congenital maltose intolerance, a serious disorder that requires the exclusion of maltose, starch, and glycogen from the daily diet or the addition of maltase to food.


Khimiia uglevodov. Moscow, 1967.
Harris, H. Osnovy biokhimicheskoi genetiki cheloveka. Moscow, 1973. (Translated from English.)



C12H22O11 A crystalline disaccharide that is a product of the enzymatic hydrolysis of starch, dextrin, and glycogen; does not appear to exist free in nature. Also known as maltobiose; malt sugar.


a disaccharide of glucose formed by the enzymic hydrolysis of starch: used in bacteriological culture media and as a nutrient in infant feeding. Formula: C12H22O11
References in periodicals archive ?
2004), administrando solucoes com diferentes concentracoes de maltose, sacarose e dextrina em ovo, encontraram que pintos oriundos de ovos suplementados com os carboidratos apresentaram maiores pesos na eclosao em relacao aos nao-suplementados.
0001) by MRD after the administration of the high maltose diet and changed from 87 to 91 mg/dl within 30 min.
Lactose and maltose are lower in sweetening power and are often used either to prevent the Maillard reaction or to reduce sweetness.
Immune globulin intravenous (IGIV) is a sterile, highly purified immunoglobulin G (lgG) preparation made from pooled human plasma stabilized with glucose, maltose, glycine, sucrose, sorbitol, or albumin and is used as prophylaxis or therapy for various medical disorders.
Production of these enzymes was repressed or completely inhibited in the control cultures containing maltose or glucose as carbon sources and enzyme inducers.
coli strains when grown on the sugars glucose and maltose (a glucose dimer).
Cluster analysis of sugar suggests highest similarity of fructose, maltose and galactose and least similarity of sucrose under cluster III and cluster I.
5 ul/litre) blood agar and fermentation of sugars (L-arabinose, glucose, lactose, maltose, mannose, raffinose, salicin, D-sorbitol, starch, mannitol, rhamnose and sucrose) were performed according to standards procedures (Holt, 1986).
There are 50 different names for sugar and here are just some of the more obscure; Barley malt, cane juice crystals, crystalline fructose, dextran, dextrose, diastase, ethyl maltol, evaporated cane juice, maltodextrin, maltose, mannitol and panocha.
In addition to white, brown, cane, date, beet, turbinado, and demerara sugar, terms for sugar include corn syrup, brown rice syrup, malt syrup, maple syrup, fruit juice concentrate, molasses, barley malt, cane juice and evaporated cane juice, honey, agave nectar, dextrose, fructose, sucrose, lactose, and maltose.
High yield of enzyme produced from carbon sources such as maltose [8] and sucrose have been reported by other researchers.