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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<strong>and</strong> elimination <strong>of</strong> the demineralization step in chitin preparation, decre<strong>as</strong>ed the viscosities <strong>of</strong><br />
<strong>chitosan</strong> samples, where <strong>as</strong> Moorjani et al. (1975) indicated that it is not desirable to bleach the<br />
material at any stage since bleaching considerably reduces the viscosity <strong>of</strong> the final <strong>chitosan</strong><br />
product.<br />
4. Atmosphere<br />
Many scientists have agreed that free access <strong>of</strong> oxygen to chitin during deacetylation h<strong>as</strong><br />
a substantial degrading effect on <strong>chitosan</strong>. Deacetylation in the presence <strong>of</strong> nitrogen yielded<br />
<strong>chitosan</strong> <strong>of</strong> higher viscosity <strong>and</strong> molecular weight distributions than did in air. However, little<br />
differences in nitrogen <strong>and</strong> <strong>as</strong>h compositions were observed (Bough et al., 1978; Lusena <strong>and</strong><br />
Rose, 1953; Rigby, 1936).<br />
5. Ratio <strong>of</strong> Chitin to Alkali Solution<br />
Moorjani et al. (1978) emph<strong>as</strong>ized that the ratio <strong>of</strong> chitin solids to alkali solution plays a<br />
significant role in determining the quality <strong>of</strong> <strong>chitosan</strong>, b<strong>as</strong>ed on viscosity determination. The<br />
reported solid to solution ratios range from 1:10 to 1:100 on a wet b<strong>as</strong>is, <strong>and</strong> 1:4 on a dry b<strong>as</strong>is or<br />
when dry heating is used.<br />
6. Particle Size<br />
Particle size in <strong>chitosan</strong> productions h<strong>as</strong> sparked controversial reports on its effect on<br />
<strong>chitosan</strong> quality. Some agree that small particle size is better than large particle size. According<br />
to Bough et al. (1978), smaller particle size (1mm) results in a <strong>chitosan</strong> product <strong>of</strong> both higher<br />
viscosity <strong>and</strong> molecular weight than that <strong>of</strong> larger particle size (above 2 to 6.4 mm). The larger<br />
particle sizes require longer swelling time resulting in a slower deacetylation rate. However,<br />
Lusena <strong>and</strong> Rose (1953) indicated that the size <strong>of</strong> chitin particle within the 20-80 mesh range<br />
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