physicochemical and functional properties of crawfish chitosan as ...
physicochemical and functional properties of crawfish chitosan as ...
physicochemical and functional properties of crawfish chitosan as ...
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under severe conditions caused depolymerization <strong>and</strong> deacetylation. Shahidi <strong>and</strong> Synowiecki<br />
(1991) reported a 2 hr extraction period for removal <strong>of</strong> all proteins present in the shells. These<br />
workers also observed that relatively high ratios <strong>of</strong> solid to alkali solution, 1:10 or above is<br />
usually used to obtain uniformity in reaction with proper agitation.<br />
Cho <strong>and</strong> No (1999) performed deproteinization by autoclaving under conditions <strong>of</strong> 15<br />
psi/121 o C with 3% NaOH for 15min <strong>and</strong> a solid: solvent ratio <strong>of</strong> 1:10. Their results showed that<br />
deproteinization can effectively be achieved by autoclaving conditions because no significant<br />
differences in nitrogen content <strong>and</strong> bulk density <strong>as</strong> well <strong>as</strong> water <strong>and</strong> fat binding capacity were<br />
observed. Rout (2001) investigated the effects <strong>of</strong> process modification <strong>of</strong> <strong>crawfish</strong> chitin <strong>and</strong><br />
<strong>chitosan</strong> production by reversing the first two steps (deproteinization or demineralization) or<br />
reducing the number <strong>of</strong> steps (deproteinization or decoloration or both) on fat <strong>and</strong> water binding<br />
capacities <strong>of</strong> chitin <strong>and</strong> <strong>chitosan</strong>s; he reported that simplifying the process affected both water<br />
<strong>and</strong> fat binding capacities. Among crab <strong>and</strong> <strong>crawfish</strong> <strong>chitosan</strong>s, the DMPA <strong>crawfish</strong> <strong>chitosan</strong> had<br />
the highest fat binding capacity.<br />
No et al. (2002) investigated the effects <strong>of</strong> elimination <strong>of</strong> deproteinization step or<br />
reduction <strong>of</strong> alkali treatment time on <strong>physicochemical</strong> <strong>and</strong> <strong>functional</strong> <strong>properties</strong> <strong>of</strong> <strong>chitosan</strong><br />
products. Chitosan prepared without deproteinization had comparable nitrogen content, lower<br />
degree <strong>of</strong> deacetylation, solubility, water <strong>and</strong> fat binding capacity, <strong>and</strong> lower dye binding<br />
capacity, but higher molecular weight <strong>and</strong> viscosity than <strong>chitosan</strong>s prepared with<br />
deproteinization treatment.<br />
2.5.2 Demineralization<br />
Demineralization is conventionally accomplished by extraction with dilute hydrochloric<br />
acid at room temperature to dissolve calcium carbonate to calcium chloride. Among such<br />
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