What is the Difference Between Chitin and Chitosan

The key difference between chitin and chitosan is that chitin has no free amine groups, whereas chitosan has free amine groups.

Chitin is an amide derivative of glucose. Chitosan is a linear polysaccharide compound. Chitosan is produced from treating chitin with an alkaline compound such as sodium hydroxide.

CONTENTS

1. Overview and Key Difference
2. What is Chitin 
3. What is Chitosan
4. Chitin vs Chitosan in Tabular Form
5. Summary – Chitin vs Chitosan 

What is Chitin?

Chitin is an amide derivative of glucose. We can name it as a long-chain polymer material of N-acetylglucosamine. It is a type of polysaccharide that occurs as a primary component of cell walls in fungi, in the exoskeleton of the arthropods, in the radulae of molluscs, cephalopod beaks, and in the scales of fish.

Chitin is the second most abundant polysaccharide in nature that comes after cellulose. We can compare the structure of chitin with cellulose, where there are crystalline nanofibrils of whiskers. Functionally, we can compare it with the keratin protein. Moreover, this compound has important applications in medicine, industries, and biotechnological purposes.

The chemical structure of chitin was first introduced by Albert Hoffmann in 1929. He hydrolyzed this substance through a crude preparation of the enzyme chitinase. He obtained this enzyme from a snail named Helix pomatia. Chitin can be described as a modified polysaccharide containing nitrogen. The monomers that form the polysaccharide structure are N-acetyl-D-glucosamine units. These units link with each other through beta 1-4 covalent bonds. This is why we can compare the structure of chitin with the structure of cellulose that has a similar structure, but in chitin, one hydroxyl group of cellulose structure is replaced with an acetyl amine group in each monomer unit. This structure allows the chitin molecule to have an increased number of hydrogen bonds between the neighbouring polymers. Therefore, the matrix structure of chitin is strong.

When chitin is in pure form, we can observe it as a translucent compound that is pliable, resilient, and quite tough. When it is modified, it forms an even tougher structure, e.g. combination with calcium carbonate makes a tougher and less brittle structure.

When considering the uses of chitin, it has applications in agricultural and industrial fields. In agriculture, this substance can be used as a good inducer for plant defence mechanisms during the controlling of plant diseases. Other industries using chitin include the food processing industry and the production of edible films.

What is Chitosan?

Chitosan is a linear polysaccharide compound. It contains randomly distributed beta 1-4 bonds between D-glucosamine and N-acetyl-D-glucosamine. We can make this substance by treating the chitin shells of shrimp with an alkaline substance such as sodium hydroxide.

Industrially, we can produce chitosan from the deacetylation of chitin obtained from the exoskeleton of crustaceans and the cell walls of fungi. We can determine the degree of deacetylation using an NMR method.

There are different uses of chitosan, which include agricultural uses, horticultural uses, as a part of filtration processes, use as a fining agent in winemaking, medical uses, in research, in bioprinting, etc.

What is the Difference Between Chitin and Chitosan?

Chitin and chitosan are polysaccharide compounds. Chitin is an amide derivative of glucose, while chitosan is a linear polysaccharide compound. They differ from each other according to their chemical and physical properties. The key difference between chitin and chitosan is that chitin has no free amine groups, whereas chitosan has free amine groups.

The following figure presents the difference between chitin and chitosan in tabular form.

Summary – Chitin vs Chitosan

Chitin and chitosan are polysaccharide compounds. Chitin is an amide derivative of glucose, while Chitosan is a linear polysaccharide compound. The key difference between chitin and chitosan is that chitin has no free amine groups, whereas chitosan has free amine groups.

Reference:

1.“Chitosan.” Heppe Medical Chitosan.

Image Courtesy:

1. “Chitin” By Dschanz – own work (drawn with BKchem) (Public Domain) via Commons Wikimedia
2. “Chitosan chair” By Qniemiec – Own work (CC0) via Commons Wikimedia