2.2.3. Olive Leaves (OLs)

The olive leaves were collected in the crop seasons 2019/2020 from Coratina olive cultivar, stored at 4 ◦C, and processed in less than 24 h. The extraction was performed according to Difonzo et al. [10]. After washing with tap water at room temperature, the olive leaves were dried at 120 ◦C for 8 min in a ventilated oven (Argolab, Carpi, Italy) to reach a moisture content <1%, milled with a blender (Waring-Commercial, Torrington, CT, USA). The extraction from leaves was ultrasound-assisted (CEIA, Viciomaggio, Italy) and water was added in a ratio 1/20 (*w*/*v*). Three washes were done, each one for 30 min at 35 ± 5 ◦C. Finally, the extracts were filtered through Whatman (GE Healthcare, Milan, Italy) filter paper, freeze-dried, and stored at −20 ◦C. Before the analysis, the extract was filtered by nylon filters of 0.45 μm.
