**2. Materials and Methods**

#### *2.1. Plant Materials*

The research material (berries) used in this study was collected from the vineyard at the Zhengzhou fruit research institute (China) during 2020. The varieties used in the present research were 'Italia', 'Benitaka', 'Muscat of Alexandria', 'Flame Muscat', 'Rosario Bianco', and 'Rosario Rosso'. The vines were 10 years old with 'Y'-shaped tree forms. The berries of each cultivar were in the véraison stage, from 10 wpf (weeks post flowering) to 11 wpf. The red varieties showed notable change in berry color at 11 wpf (Figure 2). Three berries from the upper, middle, and lower parts of each cluster were selected from six uniform clusters. The berry skins were peeled off quickly and frozen in liquid nitrogen immediately. All frozen samples were stored at −80 ◦C for further analysis.

All the samples were allotted numbers as follows: It10 ('Italia' 10 wpf berries), It11 ('Italia' 11 wpf berries), Be10 ('Benitaka' 10 wpf berries), Be11 ('Benitaka' 11 wpf berries), Ma10 ('Muscat of Alexandria' 10 wpf berries), Ma11 ('Muscat of Alexandria' 11 wpf berries), Fm10 ('Flame Muscat' 10 wpf berries), Fm11 ('Flame Muscat' 11 wpf berries), Rb10 ('Rosario Bianco' 10 wpf berries), Rb11 ('Rosario Bianco' 11 wpf berries), Rb11 ('Rosario Rosso' 10 wpf berries), and Rr11 ('Rosario Rosso' 11 wpf berries) (as shown in Figure 2, respectively).
