Maltose (also called malt sugar) consists of two molecules of glucose. It does not generally occur by itself in foods but, rather, is bound together with other molecules. As body breaks these larger molecules down, maltose results as a by-product. Maltose is also the sugar that is fermented during the production of beer and liquor products. Fermentation is a process in which yeast cause an organic substance to break down into simpler substances and results in the production of the energy molecule adenosine triphosphate (ATP). Maltose is formed during the breakdown of sugar in grains and other foods into alcohol. Contrary to popular belief, very little maltose remains in alcoholic beverages after the fermentation process is complete; thus, alcoholic beverages are not good sources of carbohydrate.

Maltose consists of two bonded glucose units, does not occur in nature to any appreciable extent. It is fairly abundant in germinating (sprouting) seeds and is produced in the manufacture of beer. The disaccharide maltose comprises of two glucose units. Maltose is produced when starch breaks down—as it happens in human beings during digestion of carbohydrate. It occurs during fermentation process yielding alcohol. Maltose is a minor constituent of a few foods notably barley. It could be formed from starch by hydrolysis in the presence of enzyme diastase. It could be crushed into two glucose molecules by hydrolysis. The enzyme maltase in living organisms could achieve this very rapidly.

Maltose is substantial in fermentation of alcohol, as starch is changed to carbohydrates and is broken down into glucose molecules having maltase enzyme present in yeast. When barley is malted, it is brought into condition in which maltose concentration is maximized. The metabolism of maltose by yeast during fermentation which results production of ethanol and carbon dioxide.

History

Maltose was discovered by Augustin Pierre Dubrunfaut, though this discovery was not widely accepted till it was confirmed in 1872 by Irish chemist and brewer Cornelius O’Sullivan. The term is derived from malt combined with suffix ‘-ose’ which is used in names of sugars. The making and use of Maltose in China goes as far back as Shang dynasty. Use of maltose in Japan since Emperor Jimmu period.

Food Sources of Maltose

Food name	Weight (g)	Maltose (g)
Sweet potato	328	10.96
Spelt	174	8.96
Honey	339	4.88
Pizza	170	4.08
Bagels	99	3.17
Pears	251	2.76
Onion rings	166	2.24
Kielbasa	370	2.22
Cherries	253	2.20
Edamame	155	1.47
Mozzarella cheese	228	1.37
Potatoes	200	1.04
Cinnamon	65	0.93
Mamey sapote	175	0.67
Hamburger	95	0.60
Lentils	192	0.58
Tamales	186	0.41
Kiwifruit	180	0.34
Sweet corn	165	0.33
Green peas	145	0.25

Warnings

People with genetic disorders in carbohydrate metabolism such as sucrose-isomaltase deficiency might have deficiency in the enzyme required to digest maltose. It may result in nutrient malabsorption, chronic diarrhea and hypercalcemia.