Chemical characteristics of wine made by disease tolerant varieties

Vitis vinifera L. is the most widely cultivated Vitis species around the world which includes a great number of cultivars. Owing to the superior quality of their grapes, these cultivars were long considered the only suitable for the production of high quality wines. However, the lack of resistance genes to fungal diseases like powdery and downy mildew (Uncinula necator and Plasmopara viticola) makes it necessary the application of huge amounts of chemical products in vineyard. Thus, the search for alternative and more sustainable methods to control the major grapevine pathogens have increased the interest in new disease tolerant varieties. Chemical characterisation of these varieties is an important prerequisite to evaluate and promote their use on the global wine market. The aim of this project was to produce a comprehensive study of some promising new disease tolerant varieties recently introduced to the cultivation by identifying the peculiar aspects of their composition and measuring their positive and negative quality traits. A multitargeted approach using different analytical techniques (GC-MS, UPLC-MS, NMR and FTIR analysis) was adopted to investigate the main classes of volatile and non-volatile compounds which play a key role in the organoleptic and sensory properties of wine. The findings of this study provide a clear picture of the chemical profile of wine made from a selection of mildew tolerant varieties. Knowledge gained would serve to evaluate their use for quality wine production as well as to suggest the most appropriate winemaking style, allowing the improvement of the wine quality and valorisation of the characteristics of each grapevine variety. Considering that grape quality is crucial for wine quality, the chemical composition of the grapes from mildew tolerant varieties was also investigated. Additionally, bearing in mind the role of wild Vitis genotypes as a source of genetic resistance to biotic and abiotic stresses, the metabolomic profile of red grapes from non-V. vinifera genotypes was explored. By evaluating these wild genotypes, it was possible to assess the value of this grape germplasm and the information acquired could provide wider choices to the breeders. To the best of our knowledge this survey is the most extended metabolomic profiling study on non-V. vinifera genotypes.