Study of cellulose-lysozyme interactions aimed to a controlled release system for bioactives

The potential use of cellulose based materials for active food packaging applications was explored. For this purpose, the sorption of lysozyme in a cellulose based paper pulp was optimized using the experimental design methodology. A Face-Centered Composite design was applied to investigate the effect of short/long fibers ratio and carboxymethyl cellulose concentration on linking lysozyme to the fibers surface and to optimize the cellulosic matrix composition. The related polynomial model showed good fitting ability (R² > 0.9) as well as good prediction ability (Q² > 0.8). The best combination of factors was 50 % short fibers, 50 % long fibers and at least 4 % carboxymethyl cellulose. Afterwards the lysozyme release was investigated using a mathematical model based on Fick’s second law. It was able to describe the release kinetics of lysozyme from the paper sheets made with the optimized cellulosic matrix into water at different temperatures (between 4 and 23 °C), pH (from 4 to 7) and NaCl concentrations (from 0.2 to 2 M). The apparent diffusion coefficients for the lysozyme were in the range of 3.1 × 10⁻¹⁶–6.6 × 10⁻¹⁴ and the E_a value was 22.1 kJ/mol at pH 5 and NaCl concentration of 0.5 M.