What Is Maltose?
Maltose which is also known as malt is a disaccharide made up of two alpha D glucose unit. The two-unit of glucose are linked with an alpha 1,4 glycosidic bond. In the small intestinal lining in humans, the enzyme maltase and isomaltase break down the molecules of maltose into two glucose molecule, which is then absorbed by the body. Starch is the most abundant polysaccharide in plant cells after cellulose.
Meanwhile, a carbohydrate formed by joining of two units of glucose is called a disaccharide. The three common types of disaccharide are sucrose, maltose and lactose. The other disaccharides which are less commonly known are lactulose, trehalose, and cellobiose. When one water molecule is removed by joining of two monosaccharides than a molecule of a disaccharide is formed and the reaction which takes place during this process is known as dehydration reactions.
|Molar Mass||342.1162 g/mol|
|Melting Point||102-103 °C (monohydrate)|
Maltose is a disaccharide made up of two alpha D glucose in which C1 of first glucose unit is bonded to C4 of second glucose unit as shown figure below. The bond that joined two alpha glucose unit is called alpha 1,4 glycosidic linkage.
At C1 of the second glucose unit, aldehyde group can be formed in solution which makes maltose a reducing sugar.
Also Read: Glucose Structure
Properties Of Maltose
- Maltose is a reducing sugar. It tastes sweet but is only 30-60% as sweet as sugar.
- The hydrolysis reaction of maltose in the presence of an acid catalyst gives two molecules – alpha D-glucose.
- There is a free anomeric carbon present in the structure of maltose which can undergo mutarotation in solution. The resultant solution will be a mixture of alpha and beta maltose.
- Since the aldehydic group is formed in the solution, therefore, maltose gives a positive test with Benedicts and Tollens reagent.
The first discovery of maltose was made by Augustin-Pierre Dubrunfaut. However, this was not widely accepted. It was only in the year 1872 that its existence was confirmed by Irish chemist named Cornelius O’Sullivan. The term maltose has been taken from the word malt where a suffix ‘ose’ was added describing that it belonged to the category of sugar.
Maltose belongs to an important biochemical series of glucose chains. Meanwhile, maltose can be prepared by the hydrolysis of starch in the presence of the enzyme diastase. During hydrolysis, starch is broken down into two glucose molecules. Starch is also heated with a strong acid for several minutes in the process. In living organisms, the enzyme maltase helps the reaction to take place.
Also Read: Hydrolysis, Salts and Types
Uses Of Maltose
- Disaccharide such as sucrose is very sweet and is used as a sweetener in the food product, but maltose lacks sweetness and is not used as a sweetener. Instead, it is used in the malting of barley for the manufacturing of beer.
- Used extensively in alcohol production.
- Free maltose as well as maltose formed by the digestion of starch in the mouth, can cause dental caries.
- Enzyme maltase and isomaltase present in the small intestine break down maltose into two glucose units which are then absorbed. Our body has the capacity to absorb maltose directly which later on can be broken down into glucose unit for producing energy
- Due to a high glycemic index, maltose increases blood sugar level.
Structural Difference Between Sucrose, Lactose And Maltose
Maltose, sucrose and lactose they all are disaccharides made up of glucose units. Disaccharides are sugar and so are monosaccharides. These three sugars mentioned above have different components.
Maltose is composed of two molecules of glucose while sucrose is made up of one molecule of glucose and another one is fructose which is also a monosaccharide. Lactose is made up of one molecule of glucose just like maltose but the second component of this lactose is different from sucrose, instead of fructose it is made up of galactose which is also a monosaccharide.
Difference Between Maltose And Cellobiose
Both the maltose and cellobiose are disaccharides sugars which are made up of two molecules of glucose and both are linked together between C1 of one sugar and C4 of the other sugar. But the first glucose unit in maltose is the alpha anomer while first glucose unit in cellobiose is the beta anomer of glucose.
Fig: (1) structure of maltose. (2) structure of cellobiose
Both the maltose and cellobiose are the disaccharides but the main differences are given below.
- Maltose is an intermediate sugar form by the action of amylase catalyzed hydrolysis of starch. Maltose is composed of two units of D- glucose linked together through alpha 1,4 glycosidic bond.
- Cellobiose is an intermediate sugar formed by the hydrolysis of cellulose by enzyme cellulase. Cellobiose is composed of two units of D- glucose linked together through a beta-1,4 glycosidic bond.