9420.pdf

5.4.7 Chitin and Chitosan
Chitosan is a high molecular weight carbohydrate polymer manufactured from chitin in
shrimp and crab wastes ( Bough, 1976). An estimated 120,000 tons of chitin can be
produced annually on a worldwide basis (Knorr, 1991). Shells are first ground, protein
is extracted, and the shells are demineralized. After washing and dewatering chitin is
recovered. Chitin is converted to chitosan by deacetylization. Proposed applications of
chitin - chitosan include (Gates, 1991, Johnson and Peniston, 1971, Knorr, 1991, Bough,
1976):
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water treatment flocculent for: recovery of food processing byproducts
(especially proteins), biosorption of heavy metals, removal of dyes and
pesticides;
surgical sutures;
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contact lenses;
burn dressings;
immobilization agent in cell cultures;
agricultural nematocide;
digestive aid;
coatings for paper and for glass fibres to permit dyeing;
encapsulation agent for pharmaceuticals;
viscosity control agents for drilling muds;
biodegradable packaging films;
dietary supplement in fish farming;
clarification of beverages.
A substantial investment in chemical processing equipment and technical personnel is
required for chitin - chitosan production (Green and Mattick, 1977). Japanese production
of chitin - chitosan currently exceeds 300 tons per year, with pilot scale production in the
United States (Gates, 1991 ).
5.4.8 Food Flavours
Concentrated clam and oyster cook water can be converted into, marketable food
products such as clam juice, dehydrated clam flavour used for soups, dips and snacks
and fermented oyster sauce (Hood and Zall, 1979 and Gates, 1991).
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