Antifungal and physicochemical properties of starch-lignin based-films

Biopolymeric films offer an ecological alternative to obtain containers or coatings for food. These offer a barrier against moisture and are biocompatible. Mixtures of different polymers make it possible to obtain materials with unique physicochemical properties. The objective of this study was to assess the effect of different soluble fraction of organosolv lignin on the antifungal and physicochemical properties of starch films. The lignin was extracted using a mixture of organic solvents, fractionated in alcohol, and the alcohol-soluble lignin fraction was incorporated into starch films at concentrations of 1, 3, 5, and 10 %. The resulting films underwent analysis through Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electronic Microscopy (SEM). Additionally, thickness, color, the mechanical properties, and the inhibition capacity against P. italicum fungus of the films were also evaluated. The FTIR and SEM results revealed significant chemical interactions between starch and alcohol-soluble lignin fraction confirming a correct integration of both polymers. Moreover, the incorporation of alcohol-soluble lignin fraction had a plasticizing effect on the films, substantially enhancing their flexibility. Regarding antifungal activity, the films with 5 % alcohol-soluble lignin fraction exhibited the highest percentage of inhibition of the P. italicum fungus (91.7 ± 0.56 %), while the lowest inhibition was obtained in the films containing 10 % (64.0 ± 0.32 %). The starch/ alcohol-soluble lignin fraction films demonstrated effective antifungal in vitro properties, providing a viable alternative to control the development microorganism that affect the shelf life of foods.