Toward the rational design of bio-based active films: Integrating polymer matrix and pomegranate peel-derived bioactive fractions

Abstract

The development of sustainable active packaging materials requires a rational understanding of the interactions between polymer matrices and bioactive components. In this work, bio-based films based on alginate, gelatin, and poly(vinyl alcohol) (PVA) were functionalized with different pomegranate peel-derived fractions, including powder, extract, and DES-extracted lignin. The incorporation of these components markedly influenced the physicochemical and functional properties of the films. Extract-containing systems exhibited increased water dissolution and reduced glass transition temperatures (by several degrees), indicating enhanced polymer chain mobility, whereas powder-containing systems showed higher surface roughness and thickness, reflecting a more heterogeneous structure due to the presence of dispersed particles. The antioxidant activity was strongly dependent on the type of fraction, with the extract displaying the highest reducing power, while lignin contributed through its polymeric phenolic structure. The incorporation of pomegranate-derived fractions also improved the antimicrobial performance of the films, with extract-containing systems generally showing the most pronounced effects. Overall, the results highlight that both the nature of the polymer matrix and the type of pomegranate-derived fraction play a key role in determining film performance. Multivariate analysis further supports these findings, explaining approximately 65–70% of the variability depending on the property considered. These findings provide useful insights for the rational design of bio-based active films for food packaging applications.