Regulating the Physicochemical Properties of Chitosan Films through Concentration and Neutralization

Chitosan offers real potential for use in food preservation, biomedicine, and environmental applications due to its excellent functional properties, such as ease in the fabrication of large films, biocompatibility, and antibacterial properties. However, the production and application of chitosan films were limited by their strong residual acetic acid taste, weak mechanical properties, and poor water vapor barrier properties. In this study, the effects of the chitosan concentration in the film-forming solutions and the neutralization treatment on the physicochemical properties of chitosan films were examined. The results demonstrated that the chitosan concentration affected the mechanical and barrier properties of chitosan films without the neutralization treatment. This was mainly due to the low acetic acid contents in chitosan films after drying. Acetic acid acted as a plasticizer within chitosan films resulting in a looser network structure. After neutralization, the chitosan films showed improvements in properties, with little effect on the chitosan concentration in the film-forming solutions. Moreover, chitosan films after neutralization showed no residual acetic acid. Therefore, neutralization could effectively improve the performance of chitosan films.