Preparation and Characterization of Crayfish (Astacus leptodactylus) Chitosan with Different Deacetylation Degrees.

Background: In this study, chitosan with various deacetylation degrees was extracted from crayfish (Astacus leptodactylus) shells with the purpose of examining the effect of deacetylation on the characterization of chitosan.

Objectives: Recycling of wastes has become an important issue with the advancement of shellfish processing technology. Therefore, this study examined the most important and conventional characterization parameters of chitosan extracted from crayfish shells and investigated whether crayfish chitosan can be an alternative to commercial products.

Material and methods: In order to determine the characterization of the chitosan; degree of deacetylation, yield, molecular weight, apparent viscosity, water binding capacity, fat binding capacity, moisture content, ash content, color properties, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction analyses (XRD) were applied.

Results: The low (LDD) and high (HDD) deacetylated crayfish chitosan characterization results in terms of yield, molecular weight, apparent viscosity, water binding capacity, fat binding capacity, moisture content, ash content were 17.50%, 424.03-334.66 kDa, 16.82-9.63 cP, 481.29-428.04%, 419.30-355.75%, 3.32-1.03%, 0.98-1.01%, respectively. As detected by two different methods, potentiometric titration and elemental analysis, the deacetylation degrees of low and high crayfish chitosan were found close to each other, which were 76.98-94.98% and 73.79-92.06%, respectively. As the deacetylation period extended, acetyl groups were removed, and the degree of the deacetylation of crayfish chitosan increased while the apparent viscosity, molecular weight, water and fat binding capacity decreased.

Conclusions: The findings of the present study are important to obtain the chitosan having various physicochemical characteristics from unevaluated crayfish wastes and to use it in many different sectors, especially biotechnology, medicine, pharmaceutical, food, and agriculture.