Solvent-selective extraction of Syzygium polyanthum bioactives for tailored polyvinyl alcohol composites: A lignocellulose-derived approach toward biorefinery-based functional materials

Abstract

This study explores the valorization of Syzygium polyanthum leaves as a renewable biomass resource for the fabrication of bioactive polyvinyl alcohol (PVA) composite films. A solvent-selective extraction approach was employed using distilled water, ethanol, and methanol to isolate phytochemicals with different polarities, thereby demonstrating a separation strategy relevant to biorefinery processes. The extracted bioactives, rich in phenolics, flavonoids, and chlorophyll, were incorporated into PVA films and systematically evaluated for their optical, mechanical, thermal, moisture barrier, antioxidant, and antimicrobial properties. The results reveal that solvent choice critically determines extract composition and, consequently, film performance. Methanol-extracted bioactives produced films with superior UV-blocking and antimicrobial activity, while ethanol extracts enhanced red-light absorption due to higher chlorophyll content. Water-based extracts yielded films with the greatest mechanical reinforcement, highlighting solvent–polymer compatibility. This work demonstrates how solvent-mediated separation of biomass-derived compounds can be leveraged to tailor the performance of lignocellulose-derived composites. The findings underscore the potential of integrating extraction–separation strategies within biorefinery concepts to generate functional bio-based materials for sustainable packaging applications.