*2.1. Plant Materials*

Vine shoots of 23 varieties of *Vitis vinifera* L. were selected: Aglianico (AG), Bianco d'Alessano (BA), Bombino Bianco (BB), Bombino Nero (BN), Ciliegiolo (CI), Fiano Bianco d'Avellino (FB), Italia (IT), Malvasia Bianca (MB), Malvasia Nera di Brindisi (MN), Maresco Bianco (MA), Minutolo Bianco (MI), Montepulciano (MO), Negroamaro (NE), Nero di Troia (NT), Notardomenico (ND), Ottavianello (OT), Palieri (PA), Primitivo (PR), Sangiovese (SA), Susumaniello (SU), Trebbiano (TR), Verdeca (VE), and Vittoria (VI). All vine shoots were sampled during winter (February 2021) from a varietal collection located in Locorotondo (Puglia, Italy; coordinates: longitude 17◦133.741 E, latitude 40◦4542.763 N) grown under the same conditions. The vineyard was planted in 1985 on a sub-alkaline mediumtextured soil. About 10 kg of vine shoots from each variety, sampled from large batches and representative of these, were collected and stored intact under controlled conditions (darkness, at 15 ± 3 ◦C) for 6 weeks [34]. Then, two different representative subsamples of about 1 kg for each variety were considered for the subsequent analyses. Table 1 shows additional information about the varieties chosen in this work.


**Table 1.** The grapevine variety name, grape colour, usual use, and acronym used in the text.

### 2.1.1. Evaluation of Treatments Impact

Vine shoots from the Primitivo and Negroamaro varieties were manually cut (particle size about 5 cm long), cut crosswise, heat-treated (as described below), ground (particle size ranging from 0.2–4 mm) using a hammer mill (Dietz-Motoren KG, Elektromotorenfabrik, 7319 Dettingen-teck, Germany), and immediately submitted to extraction and analyses. Four different treatments of the vine shoots were tested before stilbene extraction (untreated, dried at 50 ◦C for 24 h, dried at 70 ◦C for 15 min, dried at 80 ◦C for 10 min). A thermostatic oven (TFC 120 forced air oven, ArgoLab) was used for the drying process. The moisture content of the vine shoots was measured using a thermobalance (Ladwag MAC 110/NP, Radwag, Poland).

### 2.1.2. Evaluation of Variety Impact

The stilbene contents of the untreated vine shoots from 23 Italian varieties were assessed. The vine shoots were manually cut (particle size around 5 cm long), cut crosswise, ground (particle size ranging from 0.2–4 mm) using a hammer mill (Dietz-Motoren KG, Elektromotorenfabrik, 7319 Dettingen-teck, Germany), and immediately submitted to extraction and analyses. The moisture content of the vine shoots was measured using a thermobalance (Ladwag Mac 110/NP, Radwag, Poland).
