Valorization of a subutilized by-product of the yerba mate industry to design active packaging material based on...

This study focused on composite film development using gelatin and raw yerba mate powder (YMP) at different concentrations (0-10 % (w/w)) by thermo-compression. The goal was to characterize the resulting materials and evaluate key properties for potential applications, including controlled release profile, antioxidant capacity, and sensitivity to pH changes. The composite films exhibited a greenish tonality, transparency (0.7-1.8 A₆₀₀/mm), and strong UV-blocking capacity for all YMP concentrations. Mechanical profiles showed a decrease in tensile strength with YMP incorporation and an increase in elongation at break of the materials. Matrix swelling decreased up to 30 % with YMP concentration, while solubility increased with YMP incorporation. Water vapor permeability of the films increased with YMP content up to 5 %, higher concentrations induced a decrease in this property. SEM micrographs showed that YMP was homogeneously distributed in gelatin-based matrices. ATR-FTIR analysis confirmed changes in the structure of gelatin due to interactions with YMP compounds promoted by heat and pressure. Regarding food packaging applications, the films' antioxidant release and their ability to sense alkaline pH conditions make them suitable for active food packaging and could be used to extend shelf life or indicate spoilage. The industrial by-product incorporation improved the techno-functional properties of the gelatin-based materials, converting lignocellulosic yerba mate waste directly into functionalized composite films, in alignment with circular economy principles.