Exploring the Plasticizing Effect of Yerba Mate Extract and Malic Acid in Potato Starch-Based Films

This study aimed to evaluate the influence of yerba mate extract (YM) (1%, 10%, 20% w/w) and malic acid (MA) (0.5% w/w) on the mechanical response of potato starch-glycerol based films (PS), targeting disposable packaging applications. YM incorporation decreased the Young's modulus and tensile strength of the films proportional to its content, while increasing elongation at break. The effect of MA was found to be synergistic, further reducing rigidity and improving flexibility. DMA analysis indicated that molecular relaxations shifted to lower temperatures with increasing YM content and MA addition, suggesting a plasticizer-like behavior. SEM images revealed surface homogeneity in MA formulations, confirming better additive-matrix compatibility, as well as the presence of nanoparticles at higher YM concentrations. These findings demonstrate that the combination of YM and MA in starch-based matrices is effective in producing flexible films, with MA20YM formulation (0.5% MA and 20% YM) showing the best overall performance.