maltose

[French, from EnglishMALT .]

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).

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 also Glucose; Maltase; Oligosaccharide.

Malt sugar, or maltobiose, a disaccharide consisting of two glucose units linked α1-4. Hydrolysed by maltase. Does not occur in foods (unless specifically added as malt) but formed during the digestion of starch. It is one-third as sweet as sucrose. First used to sweeten foods by the Chinese in the seventh century.

A double sugar (disaccharide) consisting of two glucose molecules. Maltose forms when starch is broken down in the gut. It is digested readily into its component glucose molecules in the presence of the enzyme maltase.

[MAHL-tohs] Also called malt sugar, this disaccharide plays an important role in the fermentation of alcohol by converting starch to sugar. It also occurs when enzymes react with starches (such as wheat flour) to produce carbon dioxide gas (which is what makes most bread doughs rise).

Malt sugar, a disaccharide formed in the hydrolysis of starch and consisting of two glucose residues bound by an α(1, 4)-glycoside link.

A disaccharide made from two glucose molecules. It occurs in malt extract, an energy-rich food used by some athletes.

A sugar (disaccharide) formed when starch is hydrolyzed by amylase.

This article relies largely or entirely upon a single source. Please help improve this article by introducing appropriate citations of additional sources. (June 2009)

Maltose
IUPAC name	α-D-Glucopyranosyl-(1→4)-D-glucose
Other names	4-O-α-D-Glucopyranosyl-D-glucose
Identifiers
CAS number	69-79-4 Y,(α- or β-isomer)
PubChem	6255
EC-number	200-716-5
ChemSpider ID	388329
Properties[1]
Molecular formula	C12H22O11
Molar mass	342.30 g/mol
Appearance	white powder or crystals
Density	1.54 g/cm3
Melting point	160–165 °C (anhydrous) 102-103 °C (monohydrate)
Solubility in water	1.080 g/L (20 °C)
Chiral rotation [α]D	+140.7º (H2O, c = 10)
Hazards
MSDS	External MSDS
EU Index	not listed
Related compounds
Related	Sucrose Lactose Trehalose Cellobiose
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Maltose, or malt sugar, is a disaccharide formed from two units of glucose joined with an α(1→4) linkage. It is the second member of an important biochemical series of glucose chains. The addition of another glucose unit yields maltotriose; further additions will produce dextrins (also called maltodextrins) and eventually starch (glucose polymer).

Maltose can be broken down into two glucose molecules by hydrolysis. In living organisms, the enzyme maltase can achieve this very rapidly. In the laboratory, heating with a strong acid for several minutes will produce the same result.

The production of maltose from germinating cereals, such as barley, is an important part of the brewing process. When barley is malted, it is brought into a condition in which the concentration of maltose-producing amylases has been maximized. Mashing is the process by which these amylases convert the cereal's starches into maltose. Metabolism of maltose by yeast during fermentation then leads to the production of ethanol and carbon dioxide.

The structure of β-maltose.

Maltose as food

Plain maltose has a sweet taste, about half as sweet as glucose and about one-sixth as sweet as fructose.

Maltose syrup

In Southern China, Taiwan, Hong Kong and Macau, maltose is a common ingredient in confectionery. The most common way to consume it is to put a layer of maltose between two pieces of biscuits (usually crackers).

Maltose with biscuits

^{[citation needed]}

References

1. ^ Weast, Robert C., ed. (1981), CRC Handbook of Chemistry and Physics (62nd ed.), Boca Raton, FL: CRC Press, p. C-367, ISBN 0-8493-0462-8 .

External links

• Detailed Views of Maltose Binding Protein
• Elmhurst College Virtual Chembook

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