Chitosan is a polysaccharide composed of glucosamine and acetylated glucosamine polymers, which can be obtained by partial deacetylation of chitin in the shell. It also naturally exists in certain microorganisms and yeast. The term chitosan refers to a series of chitosan polymers with different molecular weights (50 kDa to 2000 kDa), viscosities, and degrees of deacetylation (40% to 98%). Chitosan is insoluble in neutral and alkaline solutions, but can form salts with inorganic and organic acids such as glutamic acid, hydrochloric acid, lactic acid, and acetic acid. The amino groups of polymers are protonated, resulting in soluble polysaccharides with positive charges. The most commonly used chitosan salts are glutamate and hydrochloride.