Unseparated Olive Pruning Waste as a Sustainable Feedstock: DoE-Optimized Extracts with Antioxidant Activity Equivalent to Isolated Leaves

Olive cultivation generates substantial pruning waste, yet current valorization strategies focus solely on leaves despite the logistical challenges of separating them. This study optimized the extraction of bioactive compounds from unseparated pruning waste (branches and leaves) using a D-optimal design of experiments to evaluate solvent composition, temperature, and time effects in thirteen experiments. Optimized conditions were scaled up, and extracts were tested via DPPH, ORAC assays, and ROS inhibition in HaCaT cells. Extracts from unseparated pruning waste demonstrated antioxidant capacity equivalent to isolated leaf extracts, and effectiveness in reducing the oxidative stress by approximately 60% compared to the H₂O₂ condition. This approach eliminates costly leaf separation while maintaining bioactivity, offering a scalable circular economy solution for olive waste management. The practical implications are substantial: whole pruning waste valorization reduces processing costs and time, decreases agricultural waste by utilizing currently discarded branches, and simplifies supply chains for industries requiring olive-derived antioxidants. Our findings challenge the current paradigm in olive waste biorefining, providing a more economically viable and environmentally sustainable pathway for producing antioxidant-rich extracts suitable for cosmetics, nutraceutical, and pharmaceutical applications.