Optimization studies of extraction of chitin and chitosan from pink shrimp (Penaeus notialis) shell waste and of the degree of deacetylation (DDA) of extracted chitosan were investigated via the Box-Behnken design of experiments using response surface methodology. Robust quadratic models for predicting the extraction yields of chitin and chitosan and DDA of chitosan were obtained. These models were verified by determining their eigenvalues and determinants, thereby revealing the nature of the optimum points and Hessian matrices. The respective modelled optimization conditions for the maximum yields of chitin and chitosan and for the highest DDA of chitosan were obtained thus: (3.25 M HCl solution, 19.03 h demineralization time, 2.43 M NaOH solution, and 2.03 h deproteinization time), (50% w/w NaOH solution, 87.9°C deacetylation temperature, and 145.26 min deacetylation time) and (50% w/w NaOH solution, 97.2°C deacetylation temperature, and 90 min deacetylation time). Excellent agreements were achieved between the experimental responses (extraction yields of chitin and chitosan, and DDA of extracted chitosan) and their predicted values with % error <5 in all cases.
Key words: Chitin, deproteinization, deacetylation, chitosan, optimization, response surface methodology.
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