Chitin the precursor of chitosan, is a linear polymer of mainly -(1 → 4)-2-acetamido-2-deoxy-d-glucopyranose unitsand low amounts of -(1 → 4)-2-amino-2-deoxy-d-glucopyranoseresidues. The polymer is highly acetylated and is insoluble in water. It is one of the most abundant biological materials in the world an dis after cellulose and next to lignin the most biosynthesized poly-mer. When the degree of N-acetylation (DA) is lower than 50% it isentitled chitosan