**2. Materials and Methods**

#### *2.1. Raw Materials*

Commercial rice flour, corn starch, guar gum and *Psyllium* fiber were from Chimab Campodarsego (Padova, PD, Italy). Fresh compressed yeast, salt and sugar were purchased from a local supermarket. Sunflower oil was from Carapelli Firenze (Florence, Italy).

#### *2.2. Preparation of By-Product Extracts*

#### 2.2.1. Olive Leaf Extract

The OL were collected in the crop season 2020/2021 from Coratina olive cultivar, stored at 4 ◦C, and processed in less than 24 h. 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%, and then milled with a blender (Waring-Commercial, Torrington, CT, USA). The extraction process was ultrasound-assisted (CEIA, Viciomaggio, Italy) and water was added in a ratio 1/20 (*w*/*v*). After three washings, each performed for 30 min at a temperature of 35 ± 5 ◦C, the extracts were filtered through Whatman filter paper (GE Healthcare, Milan, Italy), freeze-dried, and stored at −20 ◦C. Before the analysis, the extract was further filtered by using nylon filters (0.45 μm pore-size).
