Identifying Viticultural Factors that Directly Influence Acidity in Winegrapes
Abstract
High wine pH is an important challenge in hot climates due to pH’s influence on red wine color, oxidation, flavor, and cold and microbial stability. In order to increase grape acidity in the vineyard and decrease the pH, viticultural factors that directly influence grape berry acidity need to be determined. For this purpose, a two-year field study was conducted in seven commercial V. vinifera cv. ‘Tempranillo’ vineyards located in the Texas High Plains and North Texas regions. Data on cultivar, canopy architecture, soil and vine nutrition, climate, harvest yield, and berry composition were collected from twenty consecutive vines from each vineyard site. Partial least squares regression (PLSR) models were constructed to predict factors that influence acidity at individual vineyard sites and across all vineyard sites by year and collectively. The variance in juice pH observed across sites and within individual sites was best explained by juice potassium (K). Juice pH increased with the increase in total K concentrations in the berry. Rootstock selection and vine water status were also important factors to the models. Results from the study indicate that proper rootstock selection and water management are important factors for reducing K and pH in grape juice. The strong correlation between K and juice pH was further investigated in four additional V. vinifera cultivars. ‘Malbec’, ‘Grenache’ and ‘Carnelian’ also showed a strong positive correlation between K and juice pH.
Citation
Sampson, Rachael Ann (2021). Identifying Viticultural Factors that Directly Influence Acidity in Winegrapes. Master's thesis, Texas A&M University. Available electronically from https : / /hdl .handle .net /1969 .1 /193075.