physicochemical and functional properties of crawfish chitosan as ...

CHAPTER 1
INTRODUCTION
Chitosan is a natural carbohydrate biopolymer derived by deacetylation (DA) of chitin, a
major component of the shells of crustacea such as crab, shrimp, and crawfish. After cellulose,
chitin is the second most abundant natural biopolymer found in nature (No and Meyers, 1989).
Like cellulose, chitosan is a fiber. However, unlike plant fiber, chitosan possesses unique
properties including the ability to form films, optical structural characteristics and much more.
Chitosan also possesses a positive ionic charge, which gives it the ability to chemically bind with
negatively charged fats, lipids and bile acids (Sandford, 1992).
Chitosan is a non-toxic, biodegradable and biocompatible polymer. Over the last several
years, chitinous polymers, especially chitosan, have received increased attention as one of the
promising renewable polymeric materials for their extensive applications in the pharmaceutical
and biomedical industries for enzyme immobilization and purification, in chemical plants for
wastewater treatment, and in food industries for food formulations as binding, gelling, thickening
and stabilizing agent (Knorr, 1984).
Chitosan is easily obtained from crab especially Dungeness crab (Cancer magister),
shrimp particularly the Pacific shrimp (Pandalus borealis), lobster, or crawfish shells. These are
the richest source of chitin and the major U.S. sources of crustaceans that are processed into
chitin and chitosan (Knorr, 1991). Louisiana has the largest and oldest successful crustacean
farming industry in the U.S, namely the red swamp crawfish (or crayfish) Procambarus clarkii.
This aquaculture industry currently has an annual production capacity in excess of 100 million
pounds, of which approximately 80% is consumed locally and 15% is marketed throughout the
U.S. In addition, the processing plants annually generate as much as 80 million pounds of
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