Inherently acidic films based on chitosan lactate-doped starches and pullulan as carries of nisin: A comparative study of controlled-release and antimicrobial properties

Nisin (NIS) Z was incorporated (0.05 %, 0.1 %, 0.2 %) into edible films based on chitosan lactate (CHL) and 75/ 25 blends of polysaccharides (corn starch (CS), wheat starch (WS), oxidized potato starch (OPS), pullulan (PUL)) with CHL. The increase in the NIS/polymer ratio promoted the diffusion-driven release. Compared with the fully dissolvable CHL and PUL/CHL carriers, the starch/CHL films had limited solubility (approximate to 27-37 %) and, consequently, ensured slower/incomplete release of NIS. The assayable NIS half-release times, determined in water, ranged from <1 min to similar to 13 h. Probably due to the similar pH (approximate to 4.5), there were generally no large differences between the antibacterial activities of the formulations. The NIS-supplemented systems limited the growth of some pathogens (B. cereus, L. monocytogenes, S. aureus), phytopathogens (P. carotovorum), and bacterial starter cultures. The NIS improved the UV-blocking ability of the films, but the 0.2 % NIS addition weakened (by approximate to 17-32 %) the tensile strength of most of the films.

Automated summary

Nisin Z was incorporated into edible films with different formulations, and the release rate was influenced by the NIS/polymer ratio. Starch-based films showed slower release of NIS compared to CHL and PUL/CHL carriers. NIS exhibited antibacterial activity against certain pathogens and improved UV-blocking ability of the films, but high concentration of NIS weakened the tensile strength of the films.