La pigiatura dell'uva: un caso studio di mosti e vini base Franciacorta DOCG

This thesis focuses on evaluating pressing techniques and technologies and their influence on the specific characteristics of must and wine produced from two grape varieties. Pressing plays an important role for the appropriate composition of wine and extraction of desired compounds and as such is a crucial and often under researched step in wine making. This importance is even greater in the case of production of sparkling wine which are characterized by high acidity and low pH as well as to low content of phenolics Recognizing the pivotal role of pre-fermentative steps, in shaping wine attributes, this study aims to analyze pressing conditions as one step in the production of wine to advance knowledge in this domain. Grape samples, obtained from 6 wineries underwent either on-site pressing (Industrial) at the wineries or laboratory pressing, forming two distinct sample groups. Both sets were independently analyzed for various chemical parameters to assess the impact of pressing conditions on the chemical profile of finished wines. The parameters being tested for were pH, titratable acidity, color index, turbidity, antioxidant activity, total phenolic index, total flavonoids, and polyphenol oxidase enzyme. In addition to these, homogenized samples were prepared to test for the total and extractable flavonoids. The industrial must was also tested for several chemical parameters including potassium, iron, copper, alfa amino nitrogen, and ammonium. Results from the 2023 harvest analysis revealed significant correlations and trends, for example the higher extractability of Pinot Blanc compared to Chardonnay. These findings provide valuable information for pressing decisions. Several parameters, including the impact of potassium levels on acidity and the correlation between acidity and pH, aligned with existing literature. Despite lacking multiyear comparisons, this analysis establishes novel connections between pressing conditions and the chemical profile of musts, emphasizing the impact within a narrow sample. The relevant impact of pressure applied was further demonstrated on both acidity and pH. Moreover, the importance of pressing of phenolic extraction was evidenced being a parameter affected by the grape variety. The content of phenols can be with pH and acidity taken into account for must fractioning, the key step for the sparkling wine production. This report constitutes the second year of a three-year study, designed for replication to derive broader conclusions. While the analysis presents correlations, trends, and relative significance of numerous chemical parameters, it refrains from drawing definitive conclusions on the efficacy of the studied presses. Through detailed analysis of pressing technologies, the study aims to provide winemakers with insights from musts to finished wine as they pertain to the pressing procedures. This research advances winemaking practices by unraveling the intricate relationship between pressing methodologies and wine quality, enhancing precision in the Franciacorta DOCG region. In summary, this report contributes to the broader research goal of optimizing pressing cycles for enhanced winemaking in the Franciacorta DOCG. As the study progresses over subsequent years, it aims to offer a comprehensive understanding of pressing effects, enabling winemakers to make informed decisions for improved wine quality and production efficiency.