ABSTRACT This study investigates the synergistic potential of yerba mate extract (YM: 0–20 wt%) and malic acid (MA: 0.5 wt%) as functional modifiers in solvent‐cast potato starch (PS) films. Films were characterized through CIELab colorimetry, SEM, contact angle measurements, moisture absorption analysis (75% and 98% RH), and FTIR‐ATR. YM incorporation produced concentration‐dependent color shifts characterized by reduced lightness and enhanced green‐yellow pigmentation. MA significantly improved surface gloss while promoting homogeneous morphologies observed via SEM, contrasting with YM‐induced roughness from particulate aggregation. Wettability analysis revealed YM reduced hydrophilic character, whereas MA enhanced hydrophilicity through accelerated droplet spreading kinetics. Crucially, both additives reduced moisture uptake: YM via phenolic‐starch interactions limiting hydroxyl availability, and MA through crosslinking that restricted chain mobility, as supported by FTIR‐ATR analysis. The combined MA–YM formulation at highest YM concentration (MA20YM) exhibited optimal moisture barrier performance. These findings suggest that synergistic modification with YM and MA offers a promising approach for developing sustainable starch‐based packaging.
Casagranda et al. (2026) studied this question.