Influence of Extraction Conditions on Yield, Physicochemical Characteristics, and Degree of Deacetylation of Chitosan Derived from Black Soldier Fly Cocoons

Abstract

Black soldier fly (BSF) cocoons are a chitin-rich byproduct and a sustainable chitosan source. This study evaluated eight extraction protocols varying alkali type (sodium hydroxide (NaOH) or potassium hydroxide (KOH)), concentration, temperature, and duration, followed by HCl demineralization. Commercial chitosan was included as a reference material for chemical composition, physicochemical characteristics, DD, and FTIR comparison. Extraction conditions significantly affected ash, nitrogen, recovery of chitin-rich and chitosan-rich fractions, bulk density, and degree of deacetylation (DD) (P < 0.01). Recovery of chitin-rich and chitosan-rich fractions ranged from 28.14–64.32% and 23.01–49.68%, respectively. The best-performing protocol among those tested (NaOH 1.25 M, 90 °C, 2 h; HCl 0.5 M, 1 h; NaOH 40%, 100 °C, 4 h) produced chitosan with the highest DD (82.05%), greatest solubility (27.27%), low bulk density (0.066 g/mL), and low ash (0.635%). Commercial chitosan showed higher DD (89.95%) and solubility (97.43%) than the BSF cocoon-derived samples. FTIR supported the presence of characteristic chitosan functional groups, and SEM showed morphologies from compact lamellae to porous, honeycomb-like structures. Further side-by-side structural and application-specific testing is needed to confirm its suitability for food, biomedical, environmental, and animal nutrition applications.