Viticultural and Biotechnological Strategies to Reduce Alcohol Content in Red Wines

Abstract

Viticultural and biotechnological strategies are two approaches to deal with higher must sugar levels at harvest time. A wide range of factors could signiicantly afect sugar accumulation in the grape such as choice of vineyard site, soil composition, irrigation strategy, rootstock, and grape cultivar selection as well as grape yield. In this sense, approaches to canopy management are continually evolving in response to changes in other vineyard management practices; some of these could contribute to reduce soluble sugars on grape berries at harvest time. On the other hand, among possible biotechnological strategies, one of the most relevant is the control of the fermentative process by using selected yeast strains. In this chapter, we will show how some viticultural practices have inluenced the accumulation of soluble sugars and other enological parameters in grape berries at harvest time. We will also report how a careful yeast selection and the implementation of diferent fermentation strategies can also contribute to reduce ethanol content in wines.

The aptitude of commercial yeast strains for lowering the ethanol content of wine

“…These mainly fit into four basic groups as viticultural, prefermentation, fermentation, and postfermentation strategies (Varela et al, 2015). Viticulture strategies, as promising but long-term techniques, are based on the selection of new grape varieties with low sugar accumulation, viticultural practices adapted to unripe grapes, and different agronomical methods (Olego et al, 2016). On the other hand, postfermentation strategies such as reverse osmosis, nanofiltration, and distillation represent a short-term perspective dependent on the current EU and OIV regulations.…”

Auxins seem promising as a tuning method for balancing sugars with acidity in grape musts from cv. Tempranillo, but not defoliation or application of magnesium to leaves

“…Additionally, higher alcohol concentrations can decrease the impact of aroma, partly because they can suppress the perception of a wine's overall fruity character (Escudero et al, 2007), and partly because they affect yeast metabolism during fermentation (Bindon et al, 2013). Specifically, an increase in ethanol concentration during fermentation in conjunction with high sugar and acid concentration and low pH, as well as the addition of sulphur dioxide to the juice, exert selective pressure on the development of yeasts and bacteria during alcoholic fermentation (Du Toit and Pretorius, 2000); as a consequence, the effect of alcohol on the sensory properties of wine is such that relatively small changes in alcohol concentration can greatly influence how wines are perceived (Olego et al, 2016).…”

“…In addition to acidification technologies in winemaking, viticultural strategies can be applied to obtain lower alcoholto-acidity ratios in wine. These take advantage of the wide range of factors that can significantly affect the accumulation of both sugar and organic acids in grapes at harvest time, such as i) cultural practices; i.e., fertilisation and irrigation rates and schedules, canopy management and ripening control, ii) soil and environmental conditions, and iii) grapevine genotype -both rootstock and cultivar (Gutiérrez-Gamboa et al, 2021;Olego et al, 2016). Regarding cultural practices, a good deal of studies have explored how, in the context of global warming, these can improve unbalanced wines via i) the management of grape ripening time (Olego et al, 2016), ii) leaf removal procedures (Gutiérrez-Gamboa et al, 2021;Olego et al, 2016), iii) fertilisation strategies (Marcuzzo et al, 2021), which, for example, can exploit the antagonistic interactions between nutrients (Olego et al, 2016), iv) transpiration regulation approaches using sprays (Di Vaio et al, 2020;Gutiérrez-Gamboa et al, 2021) or shading nets (Gutiérrez-Gamboa et al, 2021), v) minimal pruning schemes (Gutiérrez-Gamboa et al, 2021), vi) mulching strategies (Gutiérrez-Gamboa et al, 2021), and vii) shoot and severe shoot trimming plans (De Toda et al, 2013;Gutiérrez-Gamboa et al, 2021;Zheng et al, 2017).…”