physicochemical and functional properties of crawfish chitosan as ...

(0.841-0.177 mm) had no effect on the extent of deacetylation and viscosity of the chitosan
solutions.
2.5 Some Examples of Alternative Techniques for Production of Chitosan
The characteristics of the final chitosan products differ depending on the crustacean
species from which chitin is isolated, and the production method or sequence (Cho et al., 1998;
No et al., 2000). Various procedures have been developed and proposed by many researchers
over the years for chitosan processing (No et al., 1989). There are numerous reviews on various
and diverse preparation methods for recovery and evaluation of physicochemical properties of
chitosan.
2.5.1 Deproteinization
Deproteinization is conventionally accomplished by extraction with dilute sodium
hydroxide solution (1-10%) at elevated temperature (65-100 o C) for 1-6 hr (No et al., 1995).
Bough et al. (1978) extracted protein from shrimp shells with 3% NaOH at 100 o C for 1 hr and
No et al. (1989) similarly treated crawfish shell waste with 3.5% NaOH at 65 o C for 2hr.
Optimal deproteinization can be accomplished by treatment with dilute potassium
hydroxide solution (Shahidi and Synowiecki, 1991). Cosio et al. (1982) and Chen et al. (1994) in
their various studies accomplished deproteinization for shrimp shell at pH 11.5 at 30 o C, and for
prawn in 5N NaOH for 1 hr at 100 o C, respectively. Removal of protein by enzymatic digestion
for production of chitin and chitosan was attempted by Shimahara et al. (1982), Takeda and Abe
(1962), and Takeda and Katsuura (1964) in an effort to minimize deacetylation. Bough et
al.(1978) also extracted protein from shrimp shells with Rhyzome-62 concentrate at 60 o C for 6
hr at pH 7 but complete removal of protein was not attained. Hackman (1954) and Whistler and
BeMiller (1962) attempted to extract protein for several days but prolonged alkaline treatment
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