NEW APPROACHES FOR THE PRODUCTION AND TRACEABILITY OF HIGH-QUALITY WINES

Wine industry is a climate dependent sector, affected by climate change, with both technological and economic consequences. The aim of this three-year work was to enhance the knowledge for the production of high-quality wines, preserving and increasing the varietal characteristics of autochthonous grape varieties. In addition, it aimed to improve wine traceability techniques, including the impact of different oenological treatments on wine DNA. In the first section the primary objective was to understand the development of oenological sector in the context of climate change. This allowed for a deep understanding of the improvement in the production of high-quality wines through the evaluation of a new winemaking technique the ‘cold liquid stabulation’ and also with a study on the combined effect of ripeness degree and withering rates on ‘Nebbiolo’ grapes. The cold liquid stabulation highlighted a major role of grape variety on the secondary metabolites, meanwhile the treatment itself affected some chemical-physical parameters. The results also showed variations in aroma characteristics depending on the variety, but the technique did not impact sensory features. Regarding the combined effect of ripeness degree and withering rates, these two variables can be managed according to the oenological outcome. However, the results suggested that an earliest harvest time and consequently a longer withering process, could be beneficial for the long-term aging of ‘Nebbiolo’ wines, highlighting the potential valorization of withered grapes. In the second section the genetic traceability of monovarietal wines was investigated. First a series of new single nucleotide polymorphism (SNPs) markers were identified for the most common Piedmont grape varieties ‘Barbera’, ‘Dolcetto’ and ‘Arneis’. These markers were then validated with two real-time PCR approaches: TaqMan® genotyping assays and high-resolution melting analysis (HRM), with Taq-Man® genotyping assay resulting more reliable and repeatable. Finally, the impact of most common additives, processing aids and filtration treatments, used in wine industry, on genetic traceability of ‘Nebbiolo’ wines was evaluated using a SNP-based method. These studies demonstrated that Bentonite and Gelatin had the strongest impact on DNA reduction. Moreover, grapevine DNA can also be reduced depending on filter materials and pore size. PVDF membranes with 0.22 μm showed the highest DNA reduction, resulting in the failure of SNP assay used.