159 | Innovative and sustainable strategies to recover bioactive molecules from pruning waste

Giovanna Cafeo¹, Marina Russo¹, Alessia Arena², Mariosimone Zoccali³, Paola Dugo^1|2, Luigi Mondello^1|2 | ¹Messina Institute of Technology, c/o Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy; ²Chromaleont srl, c/o Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Italy; ³Department of Mathematical and Computer Science, Physical Sciences and Earth Sciences, University of Messina, Italy.

Agricultural and food by-products constitute a significant fraction of biomass and represent a renewable source of both energy and high-value bioactive compounds. Among Mediterranean crops, Olea europaea and Citrus species are particularly widespread. Previous studies on their leaves and branches have reported the presence of numerous nutraceutical compounds with strong antioxidant activity. Since these phytochemicals do not play a role in biomass-to-energy conversion processes, they can be selectively recovered from pruning residues and exploited in the development of functional foods, cosmetic formulations, and pharmaceutical products. Therefore, the objective of the present research was to extract and characterize the main bioactive compounds from Olea europaea and Citrus pruning wastes, with a view to valorizing biomasses prior to their conversion into bio-energy. In order to achieve this goal, a range of nutraceutical classes was under investigation. Ultrasound–assisted procedures have been developed for the extraction of polyphenols, carotenoids and vitamin E, by using ethanol/water (8:2 v/v), acetone/methanol (1:1 v/v) and hexane, respectively. Subsequently, the extracts were subjected to analysis by means of hyphenated liquid chromatographic techniques (HPLC-PDA-MS, HPLC-FLD). In line with the principles of green analytical chemistry, these results served as a basis for the optimization of a single-step supercritical fluid extraction (SFE) method aimed at the simultaneous recovery of multiple nutraceutical classes. Key extraction parameters—including modifier type and concentration, flow rate, back pressure, extraction time, and temperature—were systematically evaluated. Using CO₂ with bio-ethanol as a modifier, the optimized SFE method achieved recovery rates ranging from 76% to 99% for the target compounds. Although SFE resulted in lower extraction yields compared to ultrasound-assisted extraction, it offered notable advantages in terms of automation, analytical throughput, operator safety, and material sustainability. Overall, the findings for olive and citrus pruning residues demonstrate that the proposed SFE approach represents a scalable and environmentally sustainable strategy for the recovery of diverse bioactive compounds from biomass, supporting circular economy principles.

Acknowledgements: The researches were performed with the framework of the Research Project PRIN 2022- MISSIONE 4, COMPONENTE 2, INVESTIMENTO 1.1 - BANDO PRIN 2022 - D.D. MUR n. 1858 of 08/10/2024: “Circadian - a circular economy approach for the characterization and valorization of bioactive compounds from biomass of the agri-food chain using innovative technologies”, supported by the Italian Ministry of University and Scientific Research, no. Prot. 20225NH5Z3, CUP: J53C24002500006. The authors also thank Shimadzu Corporation and Merck Life Science (Merck KGaA, Darmstadt, Germany) for their ongoing support.