Sucrose vs Fructose
Sucrose and fructose are categorized as carbohydrates. Carbohydrates are a group of compounds which are defined as “polyhydroxy aldehydes and ketones or substances that hydrolyze to yield polyhydroxy aldehydes and ketones.” Carbohydrates are the most abundant type of organic molecules on the earth. They are the source of chemical energy for living organisms. Not only this, they serve as important constituents of tissues. Carbohydrate can be again categorized into three as monosaccharide, disaccharides and polysaccharides. Monosaccharides are the simplest carbohydrate type. Glucose, galactose, and fructose are monosaccharides. Monosaccharides are classified according to,
- The number of carbon atoms present in the molecule
- Whether they contain an aldehyde or keto group
Therefore, a monosaccharide with six carbon atoms is called a hexose. If there are five carbon atoms, then it is a pentose. Further, if the monosaccharide has an aldehyde group, it is called as aldose. A monosaccharide with a keto group is called a ketose.
Disaccharides are formed by combining two monosaccharide molecules. This is a condensation reaction where a water molecule is eliminated. Sucrose, lactose, and maltose are few examples for disaccharides. Both disaccharides and monosaccharides are sweet in taste. They are soluble in water. Both are reducing sugars (except sucrose).
Sucrose is a disaccharide. It is made up of combining glucose (aldose sugar) and fructose (ketose sugar) molecules via a glycosidic bond. During this reaction, a water molecule is eliminated from the two molecules. Sucrose can be hydrolyzed back into the starting molecules when needed. Sucrose has the following structure.
This is a disaccharide that we find commonly in plants. Glucose, which is produced from the photosynthesis in leaves, should be distributed to other growing and storing parts of the plant. And sucrose is the form of transporting. Therefore in plants glucose is converted to sucrose in order to distribute them. We are familiar with sucrose in our day to day lives, because we are using this as table sugar. Industrially sugar cane and beet is used to produce table sugar. Sucrose is a white crystalline solid. It has a sweet taste, and it is readily soluble in water.
Fructose is a monosaccharide that contains six carbon atoms. Therefore, it is a hexose sugar. Further, it has a keto group, thus known as a ketose. Fructose has the following structure. Fructose is mainly present in fruits, sugar cane, sugar beet, corn, etc.
As glucose, fructose also has a simple monosaccharide structure with the chemical formula C6H12O6. Though it is shown as a linear structure, fructose can be present as a cyclic structure too. In fact, in a solution, majority of the molecules are in the cyclic structure. When a cyclic structure is forming, the -OH on carbon 5 is converted into the ether linkage, to close the ring with carbon 2. This forms a five member ring structure. The ring is also called a hemiketal ring, due to the presence of carbon that has both an ether oxygen and an alcohol group.
What is the difference between Sucrose and Fructose?
• Fructose is a monosaccharide and sucrose is a disaccharide.
• Fructose is participating in making sucrose by combining with glucose.
• Molecular weight of sucrose is higher than that of fructose.
• Chemical formula of fructose is C6H12O6. Chemical formula of sucrose is C12H22O11.
• Fructose is a reducing sugar, whereas sucrose is a non-reducing sugar.