Chitin Nanofibers as Reinforcing and Antimicrobial Agents in Carboxymethyl Cellulose Films: Influence of Partial Deacetylation

The development of edible, environmentally friendly, mechanically strong and antimicrobial biopolymer films for active food packaging has gained considerable interest in recent years. The present work deals with the extraction and deacetylation of chitin nanofibers (ChNFs) from crab shells and their utilization as reinforcing and antimicrobial agents in carboxymethyl cellulose (CMC) films. ChNFs were successfully isolated from the speckled swimming crab shells for the first time through the multistep procedures involving deproteinization, demineralization, depigmentation and mechanical disintegration. Afterward, the partially deacetylated ChNFs (dChNFs) were obtained through alkali treatment. It was found that the partial deacetylation led to the exposure of more amino groups on the surface of dChNFs and thus remarkably improved their dispersion state in an aqueous solution. The ChNF/CMC and dChNF/CMC films comprising up to 10 wt % nanofibers were prepared through the solution casting method, and their performance was evaluated and contrasted in terms of mechanical properties and antimicrobial activities. The results showed that the dChNF/CMC films exhibited superior mechanical and antimicrobial performance over ChNF/CMC films at any loadings, demonstrating the importance of ChNF surface chemistry in the development of high-performance ChNF/CMC films for antimicrobial food packaging application.