Sequential Valorization of Olive Leaf Biomass into Bioactive CMC Films: Linking Polyphenol–Polymer Interactions to Antioxidant and UV-Blocking Performance

Unlocking the potential of agricultural byproducts is key to advancing sustainable food systems. In the olive sector, pruning leaves represent an abundant yet underexploited biomass rich in phenolic compounds and structural polysaccharides. In this work, leaves from Olea europaea L. cv. “Caiazzana” were sequentially valorized: polyphenols were extracted by pressurized liquid extraction, and the residual biomass was processed into cellulose and subsequently converted into carboxymethyl cellulose (Ol_CMC). Edible biodegradable films were developed using Ol_CMC, plasticized with glycerol and sorbitol, and enriched with olive leaf polyphenols. The films were characterized for physicochemical, mechanical, thermal, and functional properties. Polyphenol incorporation reduced transparency, enhanced thermal stability and tensile strength, and significantly improved antioxidant and UV-shielding performance. Application as edible interleaves for minced chicken patties demonstrated controlled polyphenol release and preservation of bioactivity during refrigerated storage. A preliminary Life Cycle Assessment (LCA) was also conducted to identify environmental hotspots and support process optimization. These findings demonstrate a sustainable and scalable approach for the integrated valorization of olive leaves, enabling the development of bioactive, eco-friendly materials for active food packaging within a circular bioeconomy framework.