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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.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.


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

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



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.)


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


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.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


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
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
Ajwa flesh has highest percentage of glucose (54.5%) followed by fructose (52.03%), maltose (22.5%), and galactose (12.2%) except sucrose which was highest in zaidy flesh (14.1%).
enzyme activity (U) was defined as the amount of the enzyme that liberated 1.0mole of maltose from starch in 1.0L reaction mixture under the assay conditions.
euphorbiae obtida nos tratamentos contendo amido, sacarose, glicose, maltose e lactose (Tabela 2), mas o amido e, provavelmente, a fonte mais favoravel, pois estimulou acentuadamente a esporulacao.
The EML 105 system showed a positive interference from maltose but no interference from maltotriose or maltotetraose.
Maltose provides an especially interesting contrast with glucose, insofar as maltose is a disaccharide of glucose.
New Study On "2019-2025 High Maltose Syrup Market Global Key Player, Demand, Growth, Opportunities and Analysis Forecast" Added to Wise Guy Reports Database
Colobine monkeys' low sensitivity to maltose or malt sugar further suggested that the leaves they eat do not have to be starch-rich.
She had been treated by diazoxide for 10 months in a dose of 10 mg/kg/d with a 5% maltose dextrin diet, under correct glycaemic monitoring.
The pills consist of sugars lactose and maltose, which are easy to mold into a tablet, able to disintegrate, and nontoxic.
Having visited Taiwan many times both for work and for pleasure, she revealed that her favorite dessert is shaved ice, and the souvenirs she prefers are maltose candy with preserved dry plum, as well as oolong tea.
Patients who consumed the most total carbohydrates and sugars -- in the form of sucrose, fructose, lactose and maltose -- in the year preceding the cancer treatment were at greater risk of mortality from any cause during the follow-up period.