Autoclave-assisted multi-objective optimization of the deacetylation process in chitosan production from shrimp shell waste via response surface methodology

• An autoclave-assisted deacetylation method was successfully integrated with multi-objective optimization for high-quality chitosan production from shrimp shell waste. • Response Surface Methodology enabled the fine-tuning of process variables, achieving simultaneous enhancement of deacetylation efficiency and material yield. • The optimized chitosan exhibited superior structural and functional properties, including higher crystallinity, thermal stability, and antimicrobial activity. • This study demonstrates a rapid, scalable, and eco-efficient approach that supports industrial chitosan production aligned with circular bioeconomy principles. Chitosan is a versatile biopolymer with growing demand in biomedicine, food packaging, and environmental applications due to its biocompatibility and antimicrobial properties. However, producing high-quality chitosan with both a high degree of deacetylation (DD) and high yield efficiently remains challenging. This study introduces an autoclave-assisted deacetylation approach integrated with multi-objective optimization to shorten the chitosan production process from shrimp shell waste. Using response surface methodology (RSM), we optimized four key deacetylation parameters – NaOH concentration, temperature, reaction time, and solid-to-NaOH ratio – to maximize both DD and product yield. Optimized conditions (80% NaOH, 91.2 °C, 45 min autoclave time at 15 psi, 1:20 w/v ratio) produced chitosan with DD of 83.3% and yield of 85.0%, achieving a favorable balance superior to most literature reports. Notably, the autoclave-assisted process drastically reduced reaction time (to ∼2 hours) compared to conventional methods, without sacrificing deacetylation efficiency. Comprehensive characterization of the optimized chitosan showed enhanced material properties: higher crystallinity (79.9% crystallinity index) than a commercial sample (75.9%), greater thermal stability, improved mechanical strength (tensile strength 48.7 MPa vs 44.4 MPa for commercial), and stronger antibacterial activity against Staphylococcus aureus and Escherichia coli . These improvements are attributed to the optimized deacetylation, which yields a more orderly and hydrogen-bonded polymer structure. This work offers a sustainable, time-efficient route for chitosan production from waste biomass, contributing a scalable method that meets industrial needs for high-performance chitosan while minimizing processing severity. The findings support broader adoption of autoclave-assisted chitosan synthesis for advanced applications in biomedicine, food packaging, and environmental management.