Fructose - A Monosaccharide




 Fructose Monosaccharide


What is Fructose?

Fructose is a simple ketonic monosaccharide. Monosaccharides are the fundamental units of carbohydrates which cannot be further reduced to simpler compounds. They are classified based on the functional group attached to the carbohydrate. Aldose is a carbohydrate which contains an aldehyde group and ketose contains a ketonic group. It is also called fruit sugar. Fructose along with glucose and galactose are three monosaccharides which are an important part of our diet.

French chemist Augustin-Pierre Debrunfaut first discovered fruit sugar. It is found in trees, berries, honey, flowers, vine and tree fruits and most root vegetables. It is often bonded with sucrose to form a disaccharide. Commercially this sugar has been derived from corn, sugar cane, and sugar beets. But if taken in excess, it can cause obesity, insulin resistance just to name a few.

Chemical formula: C6H12O6

Physical and Chemical Properties of Fructose:

  • The carbohydrate can be fermented anaerobically with the help of yeast or bacteria in which they are converted into carbon dioxide and ethanol.
  • Fruit sugar is used in Maillard Reaction with amino acids over glucose as the reaction occurs rapidly as they are present in an open chain form.
  • These compounds dehydrate rapidly to give hydroxymethylfurfural(‘HMF’).
  • It is a white crystalline solid.
  • These carbohydrates are highly soluble when compared to other sugars.
  • They absorb moisture quickly and release it slowly into the environment with respect to other sugars.

The structure of Fructose:

  • Fructose has a cyclic structure.
  • Due to the presence of the keto group, it results in the formation of intramolecular hemiacetal.
  • In this arrangement, C5-OH combines with the ketonic group present in the second position.
  • This results in the formation of chiral carbon and two arrangements of CH2OH and OH group.
  • Hence D-fructose exhibits stereoisomerism in which α-D-fructopyranose and β-D-fructopyranose are the isomers.

Fructose- A Monosaccharide

Uses of fructose:

  • Crystalline fructose is used in enhancing the taste in food industries.
  • It is used in flavored water, energy drinks, low-calorie products, etc.
  • Fruit sugar is used in the manufacturing of soft moist cookies, nutrition bars, reduced calorie products etc.

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Practise This Question

Statement I: Glucose gives a reddish-brown precipitate with Fehling's solution. 
Statement I: Reaction of glucose with Fehling's solution gives CuO and gluconic acid. 
(IIT-JEE, 2007)