The chemical composition of disease resistant hybrid grape cultivars and its impact on wine quality: an exploratory enquiry into sustainable wines

Abstract

Disease resistant hybrid grape cultivars are now allowed in a number of EU wine PDOs, and are also accepted in a number of countries outside the EU. There is increasing interest in diseases resistant hybrid grape cultivars (RHGCs) because they allow for the production of healthy, high quality grapes with limited use of pesticides and the associated environmental and public health problems. However, the chemical composition of DRHGCs differs from Vitis vinifera, and hence winemaking protocols need to be adjusted. In particular, DRHGCs are frequently high in pH, due to their mineral content, and low in titratable acidity, due to the ability of the grapes to continue to accumulate acid post-véraison. They are also frequently low in tannins, partly due to their high protein content. This can also mean that the addition of exogenous tannins might not be sufficient to increase wine tannin levels to match Vitis vinifera wines. Depending on the species used in breeding, they can also have unusual herbaceous or ‘foxy’ aromas, which can be off-putting to consumers. In response, vignerons have trailed a number of different methods for vinifying DRHGCs, such as thermovinification, carbonic maceration, and cold soaks. The results of such trials are still inconclusive, and it is likely that different cultivars will require different approaches. This study will examine the chemistry of DRHGCs, and propose vinification techniques suitable for use in producing high quality wines. The paper is part of a broader investigation on sustainability in the wine sector and contributes to establish a scientific evidence for defining further steps in the direction of the ecological transition.