Circular Economy of Olive-Derived Polyphenols: Integrating Green Extraction, Biopolymer Encapsulation, and Advanced Analytical Strategies

The olive oil industry generates large amounts of by-products, particularly olive pomace and olive mill wastewater, which represent valuable sources of polyphenolic compounds with well-recognized antioxidant, anti-inflammatory, antimicrobial, and health-promoting properties. Within the framework of the circular economy, the valorization of these olive-derived residues has emerged as a promising strategy for converting low-value waste into high-added-value ingredients for food, pharmaceutical, and cosmetic applications. This review provides a comprehensive overview of recent advances in sustainable extraction and sample preparation approaches for the recovery of olive polyphenols, including ultrasound-, microwave-, enzyme-, and membrane-assisted technologies, as well as the use of green solvents and environmentally friendly extraction systems. Furthermore, the review discusses advanced analytical strategies for the identification and quantification of olive-derived polyphenols, covering chromatographic, spectrometric, electrophoretic, and miniaturized analytical platforms. Special attention is given to biopolymer-based encapsulation systems developed to enhance stability, controlled release, bioaccessibility, and bioavailability of these bioactive compounds. Finally, current challenges and future perspectives regarding the integration of green extraction technologies, analytical methodologies, and advanced delivery systems are highlighted to promote the sustainable exploitation of olive by-products within a circular economy framework.