Nisin diffusion in protein films: Effects of film type and temperature

Protein films [cast corn zein (CCZ), heat-pressed corn zein (HPCZ), cast wheat gluten (CWG), and heat-pressed wheat gluten (HPWG)] were studied at different exposure temperatures (5, 25, 35, and 45 degreesC) to determine nisin diffusion in aqueous model systems. Kinetics of nisin diffusion in protein films followed a Fickian diffusion model. The CCZ had the lowest nisin diffusivity and highest nisin retention. Diffusivities in HPCZ, CWG, and HPWG films were not significantly different. Temperature dependence of nisin diffusion in all films followed an Arrhenius model, which indicated no morphological changes within 5 to 45 degreesC. The activation energy for nisin diffusion in corn-zein films was higher than that in wheat-gluten films.