What Is Chitosan?
A comprehensive guide to one of the world’s most versatile biopolymers — from crustacean shells to biotech innovation.
The Basics
From Crustacean Shell to Industrial Polymer
Chitin is the second most abundant polysaccharide on Earth, after cellulose. It forms the structural component of crustacean shells, insect exoskeletons, and fungal cell walls. Chitosan is chitin where the majority of the acetyl-groups have been removed, deacetylated, exposing a functional amine-group. This chemical modification transforms an inert structural material into a bioactive, water-soluble, cationic polymer with a remarkable range of applications.
Production
How Chitosan Is Produced
Chitosan production begins with raw crustacean shells, which consist of three main components: chitin, minerals (primarily calcium carbonate), and biological residues such as proteins and lipids.
The shells are treated to remove the mineral content, and processed further to strip away the remaining biological residues, yielding purified chitin. This chitin is converted into chitosan through a controlled chemical reaction that determines the final properties of the product.
By adjusting process parameters — including temperature, reaction time, and chemical conditions — it is possible to precisely control key quality attributes such as molecular weight, viscosity, and degree of deacetylation (DDA). These parameters directly influence how the chitosan performs in a given application, which is why production control is central to delivering a consistent, application-ready product.
| Demineralisation | Removes minerals such as calcium carbonate. |
| Deproteinisation | Biological residues are removed, yielding pure chitin. |
| Deacetylation | The chitin is converted to chitosan. Reaction parameters determine the key quality attributes. |
Properties
Key Properties of Chitosan
Cationic Polymer
The amino groups protonate in acidic conditions, giving chitosan a positive charge — the basis for its flocculation and antimicrobial properties.
Biodegradable
Fully degraded by lysozyme and chitinase enzymes. Returns to nature without microplastic accumulation.
Antimicrobial
Active against gram-positive and gram-negative bacteria, yeasts and moulds through membrane disruption.
Film-Forming
Forms transparent, flexible films with good barrier properties to oxygen and oils — basis for biodegradable packaging.
Biocompatible
Non-toxic and non-immunogenic — used in wound dressings, drug delivery, and tissue engineering.
Tunable
Molecular weight and degree of deacetylation can be adjusted during production to target specific applications.