Effects of Chemical Extraction Methods on Physicochemical Properties of Shrimp Chitosan

Abstract

Chitosan extraction methods have not been applied and optimized in Cambodia whose seafood industry produced tons of shrimp shell waste yearly. This study adopted the chemical extraction method and optimized the deacetylation step from chitin to chitosan using different concentrations of sodium hydroxide (NaOH). Shrimp waste (exoskeleton) was sequentially treated with NaOH (3.5%) for deproteination at 80oC; HCl (4%) for demineralization at 80oC; NaClO (0.315%) for decolorization at ambient temperature, and NaOH (40%, 50%, 60%) at 120oC for deacetylation. Chitosan yield, moisture content, total ash, lipid, fiber, solubility, nitrogen content, viscosity, and degree of deacetylation were determined. The commercial chitosan bought from a local market was included for comparison. NaOH at 50% was found to be the optimum concentration for deacetylation based on increased solubility (96.27%), reduced ash content (0.56%) and increased degree of deacetylation (83.23) as compared to that of 40% NaOH (93.61% solubility, 1.25% ash content, and 74.45 degree of deacetylation) though chitosan yield in the former (20.59%) was lower than that in the latter (25.23%). Increasing the NaOH level to 60% had no significant advantage. Lipid and fiber contents were not significantly affected. The characteristics of chitosan extracted with 50% NaOH at deacetylation stage were comparable to that of the commercial chitosan.