Chitosan is a natural nontoxic biopolymer produced by
the deacetylation of chitin, a major component of the shells of
crustaceans such as crab, shrimp, and crawfish; chitooligosaccharides
(COS) are the degraded products of chitosan or chitin
prepared by enzymatic or chemical hydrolysis of chitosan.
Chitosan and its derivatives have shown various functional
properties that have made them possible to be used
in many fields including food [3], cosmetics [4], biomedicine
[5], agriculture [6], environmental protection [7], and wastewater
management [8]. Furthermore, biodegradable, nontoxic,
and nonallergenic nature of chitosan especially encourages
its potential use as a bioactive material [9]. Even though
chitosan is known to have important functional activities,