Impact of pre-veraison cluster treatments with nordihydroguaiaretic acid on the composition of verdejo grapes and wines

Abstract

In warmer growing regions, climate change is imposing a general increment of the temperature to the vineyards, with a greater frequency of extreme phenomena such as heat waves and droughts. The global warming is advancing and accelerating the ripening process of the grapes, which produces wines with higher alcoholic degree, lower acidity and poorer sensory characteristics. The abscisic acid (ABA) accumulation in grapes plays a crucial role in the onset of ripening, so that applying ABA inhibitors as nordihydroguaiaretic acid (NDGA) could provide musts with better sugar/acidity balance as maturation process occurs later, under lower temperatures. In a field experiment, we studied the effects of pre-veraison NDGA treatments to clusters on the composition of Verdejo must and wine. Treatments consisting of three repeated applications with 100 mM NDGA each delayed the harvest date by 4 days versus untreated controls. Total acidity, tartaric acid concentration and total polyphenol index of the must increased in treated plants, at a constant level of total soluble solid content. Data from the analysis of volatile organic compounds indicated that NDGA could contribute to the coupling of technological and aromatic maturity of grapes, then improving the aromatic profile of wines by decreasing the concentrations of total acids. Our results demonstrate that NDGA applications are potentially useful to mitigate the negative effects of global warming on the quality of wines, by increasing the acidity and polyphenol content of the musts and improving the aromatic profile of the wines.