Diffusion of Acetic and Propionic Acids from Chitosan-based Antimicrobial Packaging Films

ABSTRACT: The diffusion of acetic or propionic acids from thin (44 to 54 m m) chitosan-based antimicrobial packagingfilms in which they were incorporated was measured after immersion of the films in water, and the effects of pH (5.7,6.4, or 7.0) and temperature (4 °C, 10 °C, or 24 °C) on diffusion were investigated. The kinetics of acetic- and propi-onic-acid release deviated from the Fickian model of diffusion. Diffusion was found to be unaffected by pH in therange of values tested, but a decrease in temperature from 24 °C to 4 °C resulted in a reduction of diffusion coefficientsfrom 2.59 × 10 -12 m 2 .s -1 to 1.19 × 10 -12 m .s for acetic acid and from 1.87 × 10 m 2 .s -1 to 0.91 × 10 -12 m 2 .s -1 for propionicacid. The effect of temperature on diffusion was well (r 2 . 0.9785) described by an Arrhenius-type model with activa-tion energies of 27.19 J.mole -1 (acetic) and 24.27 J.mole (propionic). Incorporation of lauric acid or essential oils(cinnamaldehyde or eugenol) into the chitosan film at the time of preparation produced a subsequent reduction in thediffusion of acetic or propionic acid, and maximum effects were obtained with lauric acid and cinnamaldehydeincorporated to final concentrations of 1.0% and 0.5% (w/w), respectively.Key Words: diffusion, acetic, propionic, chitosan, packaging