Polyphenol extraction from Lacrima di Morro d’Alba grape pomace and Ascolana Tenera olive leaves as an effective recovery of agricultural side-streams

This study investigates green extraction methods for recovering bioactive compounds from grape pomace and olive leaves, aiming to enhance the valorization of agricultural side-streams within a sustainable framework. Conventional and innovative extraction techniques including liquid-solid extraction (SLE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and supercritical fluid extraction (SFE) were evaluated to determine their efficacy in yielding polyphenols and antioxidants, with particular attention to flavonoids, anthocyanins, and phenolic acids. Findings demonstrate that UAE optimally recovers flavan-3-ols, phenolic acids, and as anthocyanins the malvidin-3-galactoside from Lacrima di Morro d’Alba grape pomace. Otherwise for Ascolana Tenera olive leaves there is not a clear selectivity of both pre-treatment and extraction procedures applied for the recovery of oleuropein, hydroxytyrosol and tyrosol. This work underscores the potential of agrifood wastes to serve as renewable resources, fostering circular bioeconomy principles and contributing to environmental sustainability.