# Influence of Microbial Treatments on Vine Growth and Must Quality: Preliminary Results
## 2 Results and Discussion
### Chemical Composition of the Grape Juice  
The chemical composition of the grape juice obtained by pressing the grape berries is reported in Table 3. The results reveal significant differences between the samples treated with the mycorrhizal fungi product \"Ampelos\" (Bioma) and the untreated one. Notably, the Bioma-treated juice exhibited a higher concentration of organic acids, confirming the findings of [PERSON] at al., who investigated the effect of microbial treatment on \"Tempranillo\" berries. Organic acids are widespread in plants, as they are involved in important metabolic pathways leading to energy production and amino acids biosynthesis and are also fundamental in the protection against osmotic stress and fruit predation. In wine, these molecules cover two relevant functions. Firstly, they are responsible for wine pH, an important parameter affecting the appearance, microbial stability, and chemical stability of the product. Secondly, they directly impact the wine taste and, in particular, the sourness [27]. Organic acids such as tartaric, malic, and citric acids derive from wine grapes, and their content seems to be affected by different factors [28]. In detail, the investigated treated juice showed a significantly elevated malic acid content (1.88 \(\pm\) 0.5 g/L) compared to the control (1.19 \(\pm\) 0.15 g/L) and a higher concentration of tartaric acid (3.07 \(\pm\) 2.02 g/L vs. 1.92 \(\pm\) 0.21 g/L). These findings suggest that mycorrhizal treatment may contribute to a more pronounced acidity profile, potentially enhancing the freshness and the structure of the wine that is produced. Conversely, no significant differences were observed in total phenol content, although the Bioma samples showed a slight reduction (2.56 \(\pm\) 0.12 g/L) compared to the control (2.61 g/L) (Table 3). Regarding anthocyanins, Bioma-treated grape juice displayed lower levels of both total (167.51 \(\pm\) 4.13 vs. 203.39 \(\pm\) 2.86) and bleachable anthocyanins (122.54 \(\pm\) 0.30 vs. 167.51 \(\pm\) 7.42 in the control), indicating that the treatment may slightly affect the wine color intensity. However, the ratio of total to bleachable anthocyanins was higher for Bioma, highlighting that the biosynthesis of the non-oxidizable content of these secondary metabolites appears to be influenced by treatment with microorganisms (Table 3). Notably, the Bioma sample exhibited higher sugar levels (183.46 \(\pm\) 2.11 for Bioma and 157.15 \(\pm\) 7.1 for control) suggesting a potential for wines with higher alcohol content (Table 3). Finally, treatment with Ampelos appears to have a positive effect on volatile acidity since the treated samples had no detectable acetic acid, whereas the control had a concentration of 30 \(\pm\) 2.82 g/L. Indeed, the presence of acetic acid in the grapes could be associated with the grape cracking and the consequence of fermentation by indigenous microorganisms of the berry juice coming out. A high density of berries per grape could be related to a greater tendency to crushing and thus to a higher production of acetic acid, considered an undesirable compound. Figure 3: Graphical representation of Bioma and control berries in the CIELAB space in the left, graphical representation of Bioma and control seeds in the CIELAB space in the center, and graphical representation in the CIELAB space of Bioma and control marcs in the right.