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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).
..... Click the link for more information. ). 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.
..... Click the link for more information. ). 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.
..... Click the link for more information. 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.
..... Click the link for more information. 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.
..... Click the link for more information. . 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.
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.
REFERENCESKhimiia uglevodov. Moscow, 1967.
Harris, H. Osnovy biokhimicheskoi genetiki cheloveka. Moscow, 1973. (Translated from English.)
N. D. GABRIELIAN