The Main Source of Chitosan: A Deep Dive into Marine and Alternative Origins

November 7, 2025 •

3 min read

The worldwide seafood industry generates millions of tons of waste annually, and the most abundant commercial source of chitosan comes from processing this crustacean waste. This versatile biopolymer is a derivative of chitin and is highly valued for its many biomedical, agricultural, and industrial applications.

Quick Summary

The chief commercial source for chitosan is the shells of crustaceans like shrimp and crabs, derived from waste in the seafood processing industry. Other sources, such as fungi and insects, are also gaining traction as viable alternatives.

Key Points

Dominant Source: The primary commercial and industrial source of chitosan is the shells of crustaceans like crabs, shrimp, and lobsters, which are a major waste product of the seafood industry.
Chitin Precursor: Chitosan is derived from chitin, the second most abundant natural polysaccharide after cellulose, through a chemical process called deacetylation.
Extraction Process: Traditional extraction involves demineralization with acid, deproteinization with alkali, and deacetylation with concentrated alkali at high temperatures.
Alternative Fungal Sources: Fungi, such as Aspergillus niger, are gaining attention as an alternative, non-animal source for chitosan. This method is advantageous for producing allergen-free material with high purity and controlled properties.
Other Emerging Sources: Insect cuticles are another promising source, particularly with the growth of insect farming, as they contain chitin that can be extracted more simply than from crustacean shells.
Source-Dependent Properties: The source of chitosan and its extraction method influence its final properties, such as molecular weight and deacetylation degree, which in turn affect its suitability for specific applications.

What is the main source of chitosan?

Commercially, the main source of chitosan is the shells of crustaceans, primarily shrimp and crabs, which are processed as waste products from the vast seafood industry. Chitin, the precursor to chitosan, constitutes a significant portion of these exoskeletons, with shell waste containing 20-30% chitin by weight. This readily available and low-cost raw material makes crustacean shells the dominant feedstock for industrial chitosan production. The process involves converting the chitin into chitosan through a chemical process called deacetylation.

The two-step chemical process from crustacean chitin

For centuries, chitosan production has relied on a straightforward, if harsh, chemical process involving strong acids and bases.

Demineralization: The initial step involves treating the crushed and dried crustacean shells with a strong acid, typically hydrochloric acid (HCl), to dissolve and remove the calcium carbonate ($CaCO_3$). This leaves behind a fibrous material, rich in protein and chitin.
Deproteinization: The demineralized material is then subjected to a heated, strong alkaline solution, such as sodium hydroxide (NaOH), to remove proteins and other organic matter. Following this, a decolorization step might be necessary to remove pigments like astaxanthin, yielding purified chitin.
Deacetylation: The final and most critical step converts purified chitin into chitosan by treating it again with a concentrated alkali solution at high temperatures. This process removes a significant number of the acetyl groups from the chitin chain, creating the polycationic chitosan.

The growing importance of alternative chitosan sources

While crustaceans dominate the commercial market, there is a push towards exploring and scaling alternative sources of chitosan. The reliance on crustacean waste presents several challenges, including seasonal availability, potential contamination with heavy metals, and allergenicity to seafood. This has driven research into non-animal sources, particularly from fungi and insects.

Fungal-derived chitosan

Certain fungi, especially from the Zygomycetes class like Aspergillus niger and Mucor rouxii, naturally contain chitin and chitosan in their cell walls. The production of fungal chitosan is often considered a “green” and more sustainable alternative, sidestepping the chemical harshness and waste of the traditional process. Fungal chitosan offers several advantages:

It is free from animal-source allergens, making it suitable for biomedical and food applications for allergic individuals.
Production is not seasonal, as fungal biomass can be cultivated year-round through fermentation.
Fungal chitosan is typically produced with more consistent and controllable properties, such as molecular weight and degree of deacetylation.

Insect-derived chitosan

As insect farming for sustainable food and animal feed increases, so does the availability of chitin-rich waste from insect cuticles and exuviae. Similar to fungal sources, insect-derived chitosan can bypass the demineralization step often required for heavily mineralized crustacean shells. Research is ongoing to optimize extraction methods from various insect species to make this an economically viable option for large-scale production.

Comparison of chitosan sources


Feature	Crustacean Chitosan	Fungal Chitosan	Insect Chitosan
Raw Material Availability	Abundant, but dependent on seasonal seafood harvests.	Year-round, consistent supply through controlled fermentation.	Growing as insect farming becomes more widespread.
Allergenicity	Can contain allergenic proteins from crustaceans.	Generally free of allergens from animal sources.	Can contain allergenic proteins, though less common.
Extraction Process	Involves harsh chemical treatments (demineralization, deproteinization).	Simpler extraction; often omits demineralization step.	Simpler than crustacean extraction due to lower mineral content.
Process Control	Properties can vary depending on crustacean species and source.	Provides greater control over molecular weight and deacetylation.	Properties are highly dependent on the insect species and optimization.
Application Suitability	Wide range of industrial uses; needs purification for biomedical applications.	Ideal for biomedical and food applications where allergens are a concern.	Gaining importance in food and pharmaceutical industries.

The future of chitosan sourcing

The future of chitosan production is likely to involve a diversification of source materials to meet growing demand and overcome the limitations of crustacean-based production. While the large-scale, cost-effective industrial production from shrimp and crab shells will likely continue, the rise of fungal and insect-based chitosan offers compelling alternatives. The choice of source will increasingly depend on the intended application, with fungal chitosan favored for high-value biomedical and pharmaceutical products due to its purity and consistent properties. Meanwhile, insect chitosan offers a sustainable way to valorize another abundant waste stream. The ongoing innovation in greener extraction techniques, including enzymatic methods, is also making all sources more environmentally friendly. This multi-faceted approach to sourcing will ensure a steady and diverse supply of chitosan for its many beneficial applications. For further reading on the environmental considerations and innovations in chitosan extraction, a scholarly review can be found here: https://www.aimspress.com/article/doi/10.3934/ctr.2023002?viewType=HTML.

Frequently Asked Questions

No, chitosan is not derived directly from shrimp shells. The shells contain chitin, which is a precursor polysaccharide. The chitin must first be extracted from the shells and then chemically or enzymatically treated through a deacetylation process to produce chitosan.

Crustacean waste is the most common source because it is a byproduct of the large-scale seafood processing industry, providing an abundant and relatively low-cost raw material. This industrial source accounts for the majority of the world's chitosan supply.

The traditional chemical extraction of chitin and chitosan from crustacean shells uses harsh chemicals like strong acids and alkalis, producing significant wastewater and environmental waste. The process can also be prone to variations due to the seasonal availability of seafood waste.

Fungal chitosan is preferred for some high-value applications, such as biomedical and pharmaceutical products, because it is non-allergenic and can be produced under more controlled fermentation conditions. This allows for a more consistent and predictable product, and avoids the risk of shellfish-related allergens.

Yes, chitosan can be extracted from insect cuticles. As the insect farming industry grows, insect biomass is becoming an increasingly important sustainable source of chitosan. The extraction process is simpler than for crustaceans because insect cuticles have lower mineral content.

The key difference is their degree of deacetylation (DD). Chitin has a high degree of acetylation, while chitosan is the deacetylated form, meaning it has a higher number of free amino groups. This difference makes chitosan water-soluble in acidic solutions and gives it a positive charge, leading to its unique biological properties.

Raw chitosan must be processed and purified based on its intended use. For medical or food applications, extensive purification is necessary to remove contaminants. It can be further modified into different forms, such as powders, gels, or films, to optimize its performance for specific applications.