The key difference between sucrose and fructose is that sucrose is a disaccharide while fructose is a monosaccharide.
Sucrose and fructose are categorized as carbohydrates. They are the most abundant type of organic molecules on the earth. They are the source of chemical energy for living organisms. They also serve as important constituents of tissues. Carbohydrates can be 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 and whether they contain an aldehyde or keto group.
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 of disaccharides. Both disaccharides and monosaccharides are sweet in taste. They are soluble in water. Both are reducing sugars (except sucrose).
CONTENTS
1. Overview and Key Difference
2. What is Sucrose
3. What is Fructose
4. Side by Side Comparison – Sucrose vs Fructose in Tabular Form
5. Summary
What is 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. 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 are used to produce table sugar. Sucrose is a white crystalline solid. It has a sweet taste, and it is readily soluble in water.
What is Fructose?
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, the 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?
The key difference between sucrose and fructose is that sucrose is a disaccharide while fructose is a monosaccharide. Fructose takes part in making sucrose by combining with glucose. Also, the molecular weight of sucrose is higher than that of fructose. And, the chemical formula of fructose is C6H12O6 while the chemical formula of sucrose is C12H22O11. Moreover, fructose is a reducing sugar, whereas sucrose is a non-reducing sugar.
Below info-graphic summarizes the difference between sucrose and fructose.
Summary – Sucrose vs Fructose
Fructose is a monosaccharide that contains six carbon atoms. Sucrose is made up of combining glucose (aldose sugar) and fructose (ketose sugar) molecules via a glycosidic bond. The key difference between sucrose and fructose is that sucrose is a disaccharide while fructose is a monosaccharide.
Image Courtesy:
1. “Sucrose structure formula” By Bas – Self-made with Sucrose-inkscape.svg from the Commons This PNG graphic was created with Inkscape. (CC BY-SA 3.0) via Commons Wikimedia
2. “D-L-Fructose V1” By Poyraz 72 – Own work (CC BY-SA 4.0) via Commons Wikimedia