Modelling the mechanism and kinetics of ascorbic acid diffusion in genipin-crosslinked gelatin and chitosan networks at distinct pH

Crosslinked biopolymers were prepared for controlled release to investigate the diffusion of ascorbic acid from swelling high-solid networks in neutral and acidic pH conditions. Polymer swelling was measured at pH 2.8 and pH 6.8 and change in microstructural properties, including network mesh size and average molecular weight between crosslinks of genipin-crosslinked gelatin and genipin-crosslinked chitosan systems, were predicted. Variable mathematical modelling was applied to the first 60% of ascorbic acid diffusion and statistical analysis was used to determine the model that best fits the experimental data. Molecular transport from the gelatin-based networks was best described by the Peppas-Sahlin model whereas the distinct effect of pH on chitosan structure formation brought into consideration the zero-order model. Mathematical modelling of bioactive compound release from swelling biopolymer matrices at different pH conditions is essential for the design of efficient targeted delivery matrices for functional food and nutraceutical applications.