Characterization of active chitosan films as a vehicle of potassium sorbate or nisin antimicrobial agents

Antimicrobial and biodegradable active films were obtained by incorporating potassium sorbate (PS) and nisin (NIS) into chitosan matrix films. The diffusion mechanism of antimicrobial compounds through chitosan matrix was studied, applying Fick's Second Law and the Power Law. Films were produced by casting and the antimicrobial agents were added at different concentrations. They were also characterized by moisture content, water solubility, mechanical properties, contact angle, and microstructure. It was observed that the tensile strength decreased by 49.7% for PS films, and elongation increased by 206% for NIS films, when comparing 10.0 with 2.5 mg/g films. The presence of antimicrobial agents provided a significant increase in contact angle. The modeling fitted to the PS-chitosan films and the diffusivity coefficients did not show significant differences for different compound concentrations. The diffusion coefficients of PS (1.909–2.292×10⁻¹³ m²/s) were approximately two times higher than the diffusion coefficient of NIS active films.