Chitosan has a Natural Origin Index (NOI) of 1.00 (scale 0–1) per ISO 16128. Deacetylation of natural chitin removes acetyl groups as acetate; the polysaccharide backbone remains entirely shell- or fungal-derived. An NOI of 1.00 means 100% of its molecular mass is traceable to a natural, renewable source.

Is Chitosan natural? NOI 1.00

How we scored it

Chitin (natural biopolymer from crustacean shells or fungal fermentation) deacetylated with NaOH; base reagent leaves no mass. 1.0.

What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

How it’s made

Alkaline deacetylation of chitin: hydroxide attacks the acetamide C=O, the amide N leaves. Each curved arrow moves one electron pair, and the film ends on the score above.

Where it comes from

Made by alkaline deacetylation of chitin extracted from crustacean shells (shrimp, crab) or, increasingly, fungal fermentation biomass. No petrochemical route exists.

In plain English

A film-forming, hair-fixing polysaccharide derived from chitin, the natural material in crustacean shells. Treating chitin with a mild base converts it to chitosan without adding synthetic mass.

CosIng definition: Chitin, deacylated

References

1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
2CHITOSAN. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
3CHITOSAN. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=CHITOSAN