Maltose Structure Overview
Maltose is a disaccharide composed of two glucose units connected by a α-1,4-glycosidic bond. It is commonly found in grains such as barley and malted wheat and plays a significant role in various industries, including brewing and food processing. This article aims to provide a comprehensive understanding of the structure of maltose by exploring its molecular composition, bond formation, and related properties.
What is Maltose?
Maltose, also known as maltobiose or malt sugar, is a type of carbohydrate. Its chemical formula is C12H22O11. Maltose is a disaccharide composed of two units of alpha-D glucose linked by an alpha-1,4 glycosidic bond. It consists of carbon, hydrogen, and oxygen atoms. Maltose is a white crystalline powder with no odor and a sweet taste. It acts as a reducing sugar and undergoes mutarotation.
Maltose is naturally found in germinating seeds and can be produced by hydrolyzing starch in the presence of the enzyme diastase. It is an essential nutrient that supports our body's effective functioning and enables us to perform our daily activities. In humans, maltose is broken down into two glucose molecules by various maltase enzymes. These glucose molecules are further utilized for energy production or stored as glycogen for future use.
Other Name | 4-O-α-D-Glucopyranosyl-D-glucose |
Chemical Formula | C12H22O11 |
Molar Mass | 342.1162 g/mol |
Density | 1.54 g/cm3 |
Melting Point | 102-103 °C (monohydrate) |
Boiling Point | NA |
Maltose Structure
Maltose can be represented by the chemical or molecular formula C12H22O11. The structure of maltose consists of two glucose molecules linked together by an alpha-1,4-glycosidic bond. Each glucose molecule in maltose is in its pyranose form, where the six-membered ring structure is formed. The first glucose unit has its anomeric carbon (C1) involved in the glycosidic bond, while the second glucose unit's hydroxyl group at carbon 4 (C4) participates in the bonding. This alpha-1,4-glycosidic bond gives maltose its specific structure and properties. The structure of maltose can be depicted as follows:
HO-C1-O-CH2-O-C4-H
HO-C4-O-CH2-O-C1-H
This structure represents the repeating unit in maltose, where the glycosidic bond links the carbon 1 (C1) of the first glucose molecule to the carbon 4 (C4) of the second glucose molecule.
Maltose Formula with Equations
The chemical formula of maltose, C12H22O11, can be broken down to represent the number and types of atoms present in the molecule. The formula indicates that maltose consists of 12 carbon atoms (C12), 22 hydrogen atoms (H22), and 11 oxygen atoms (O11).
To further understand the structure of maltose, we can represent it using a condensed structural formula:
α-D-Glucose-(1→4)-α-D-Glucose
This condensed structural formula represents the glycosidic bond between two glucose units in maltose. The α-D-Glucose indicates that the glucose units are in the alpha configuration, and the (1→4) represents the glycosidic bond formed between carbon 1 (C1) of the first glucose unit and carbon 4 (C4) of the second glucose unit.
The equation can be written as:
C6H12O6 + C6H12O6 → C12H22O11 + H2O
This equation represents the condensation reaction that occurs between two glucose molecules to form maltose. During this reaction, a molecule of water (H2O) is eliminated, and the glycosidic bond is formed, resulting in the formation of maltose (C12H22O11).
Maltose Structure: Production
Maltose's initial discovery is attributed to Augustin-Pierre Dubrunfaut, although this is not widely accepted. However, in 1872, Cornelius O'Sullivan, an Irish chemist and brewer, confirmed the existence of maltose. The term "maltose" is derived from the word "malt," and the suffix "ose" indicates its classification as a sugar.
- Maltose naturally occurs in germinating seeds and can be produced in the presence of the enzyme diastase through the hydrolysis of starch.
- This hydrolysis process breaks down a starch molecule into two glucose molecules. In this process, starch is also subjected to heating with a strong acid for several minutes.
- In living organisms, the hydrolysis of maltose is facilitated by the enzyme maltase.
Maltose Structure: Chemical Properties
- Maltose possesses a free aldehydic group at one of its carbon atoms, making it a reducing sugar.
- Maltose is commonly found in the form of white powder or crystals.
- When maltose reacts with sulphuric acid, it produces carbon dioxide, water, and sulphur dioxide: C12H22O11 + 24H2SO4 → 12CO2 + 35H2O + 24SO2
- Hydrolysis of maltose results in the formation of ethanol and carbon dioxide: C12H22O11 + H2O → 4C2H5OH + 4CO2
- In the presence of the maltase enzyme, maltose can be hydrolyzed into glucose: C12H22O11 + H2O → 2C6H12O6
- Maltose can be detected using tests such as the Woehik test or Fearon's test.
- The melting point range of maltose is typically between 160-165 °C.
- Maltose exhibits a solubility of approximately 1.080 g/mL at 20 °C.
- The density of maltose is 1.54 g/cm³, and its molar mass is 342.297 g/mol.
Maltose Structure: Properties of Maltose
Chemical Formula | C12H22O11 |
IUPAC Name | (2R,3S,4S,5R,6R)-2-(hydroxymethyl)-6-[(2R,3S,4R,5R,6S)-4,5,6-trihydroxy-2-(hydroxymethyl)oxan-3-yl]oxyoxane-3,4,5-triol |
Molar mass | 342.297 g/mol |
Appearance | White powder or crystals |
Odour | Odourless |
Taste | Sweet taste (30 – 60% as sweet as sugar) |
Density | 1.54 g/cm³ |
Melting Point | 102 °C to 103 °C (monohydrate) 160 °C to 165 °C (Anhydrous) |
Solubility in Water | Soluble |
Detection Test | Woehik test or Fearon’s test |
Maltose Structure: Uses
- Sucrose, a disaccharide, is known for its intense sweetness and is commonly used as a sweetener in food products. In contrast, maltose lacks sweetness and is not utilized as a sweetener. Instead, it plays a crucial role in the malting process of barley to produce beer.
- Maltose finds extensive use in alcohol production, serving as an important component in the manufacturing process.
- It is important to note that both free maltose and maltose produced during the digestion of starch in the mouth can contribute to dental caries.
- In the small intestine, the enzymes maltase and isomaltase work together to break down maltose into two glucose units, which are then absorbed by the body. Our bodies have the capability to directly absorb maltose, which can later be further broken down into glucose units to generate energy.
- It is worth mentioning that maltose has a high glycemic index, meaning it can raise blood sugar levels when consumed.
Structural Difference between Sucrose, Lactose and Maltose
Sucrose, lactose, and maltose are disaccharides composed of glucose units. They vary in structure as follows:
- Maltose is formed by two glucose molecules.
- Sucrose is formed by combining a molecule of fructose and a molecule of glucose.
- Lactose is formed by combining a molecule of galactose with a molecule of glucose
Sucrose | Lactose | Maltose | |
Type | Disaccharide | Disaccharide | Disaccharide |
Units | Glucose + Fructose | Glucose + Galactose | Glucose + Glucose |
Bond | Alpha-1,2 glycosidic bond | Beta-1,4 glycosidic bond | Alpha-1,4 glycosidic bond |
Sweetness | Very sweet | Moderately sweet | Not as sweet |
Use | Common sweetener in food | Present in dairy products | Barley malting for beer |
Digestion | Broken down by sucrase enzyme | Broken down by lactase enzyme | Broken down by maltase enzyme |
Dental Effects | Can contribute to dental caries | Can contribute to dental caries | Can contribute to dental caries |
Difference between Maltose and Cellobiose
Maltose and cellobiose are both disaccharide sugars consisting of two glucose molecules linked together. The difference lies in the configuration of the glycosidic bonds and their origins:
Maltose:
- Formation: Maltose is produced by the hydrolysis of starch through the action of the enzyme amylase.
- Structure: It consists of two D-glucose units connected by an alpha 1,4 glycosidic bond.
- Anomeric Configuration: The first glucose unit in maltose is in the alpha anomer form.
Cellobiose:
- Formation: Cellobiose is formed through the hydrolysis of cellulose using the enzyme cellulase.
- Structure: It consists of two D-glucose units linked by a beta-1,4 glycosidic bond.
- Anomeric Configuration: The first glucose unit in cellobiose is in the beta anomer form.
While both maltose and cellobiose are disaccharides composed of glucose, their differences lie in their specific glycosidic bonds, their origins (starch hydrolysis for maltose and cellulose hydrolysis for cellobiose), and the anomeric configuration of the glucose units.
Maltose Structure: Things to Remember
- Maltose is a disaccharide composed of two α-D-glucose units.
- The glucose units in maltose are linked together through a glycosidic bond.
- The molecular formula of maltose is C12H22O11.
- Maltose is classified as a reducing sugar due to the presence of a free aldehydic group.
- The presence of maltose can be detected using tests such as Fehling's solution or Tollen's reagent.
- Maltose finds application in the brewing industry for beer production and is also used in sugar-free products due to its low sugar content.
- Maltose plays a significant role in the processes of germination and digestion.