Processing stability and antioxidant performance of poly(lactic acid) composites with phenolic extracts for sustainable active packaging applications

In this study, winemaking by-products were valorized for the development of an eco-friendly active food packaging material based on poly(lactic acid) (PLA). Bioactive phenolic compounds with antioxidant activity were successfully recovered from the seeds of the Greek Vitis Vinifera cultivar-Roditis (Roditis Grape Seeds Extract, RGSΕ), using solid-liquid extraction with acetone-water mixture (7:3 v/v) and a particle size ≤600 μm. A PLA composite containing 0.5 % w/w grape seed extract (PLA-RGSE0.5) was prepared via twin-screw extrusion, and thin films were produced by solvent casting. The incorporation of the extract effectively stabilized PLA against thermo-mechanical and oxidative degradation during simulated mechanical recycling (successive extrusion cycles). Furthermore, PLA-RGSE0.5 films exhibited increased water vapor permeability compared to neat PLA films but enabled the controlled release of bioactive phenols into both a lipophilic food simulant (50 % v/v ethanol-water) and a real oxidation-prone food matrix (salmon powder), extending its shelf life by 20 %. Overall, the integration of grape seed extract into PLA demonstrated promising potential for sustainable active packaging applications.