Under the title Study of new factors related to the soil, the plant and the oenological microbiota that influence the acidity balance of wines and their guarantee of quality and stability in hot climates., the new LowpHWine project will study the effects that different soil and vine conditions can have on the acid composition of grapes and wines.
Acidity in wines and climate change
And it is that the vineyard is one of the crops most vulnerable to the new conditions imposed by climate change as it is an agricultural practice limited to a very specific latitudinal range and, mainly, associated with hot regions. In the productive aspect, climate change is exerting an ever greater influence on the phenology of the vine and the composition of the grape, so that harvest after harvest, a lower acidity and a higher pH in the grape are observed, a effect that is finally transferred to the wine.
The alteration in the maturation patterns of the grape translates into obtaining grapes with a higher concentration of sugars and lower acidity, parameters that have a direct implication on the sensory quality of the wine, since lower acidity considerably affects its oenological properties. Among them, the extraction of color stands out, which contributes to premature oxidation and, therefore, to a faster depreciation over time. Sulphurous needs are also increased, that is, wines are more vulnerable to the development of unwanted microorganisms. In addition, the lower acidity affects the sensory perception of the wine and its stability over time.
However, different factors can be addressed to control pH and acidity values, as well as their influence on sensory quality and on the chemical and microbiological evolution of wines:
- Influence of varietal: considers both the characterization of relict varieties and the search for new biotypes, as well as the study of the impact of rootstocks on the acid composition of the grape.
- Influence of the soil biodiversity: studies both the role of microrhizal fungi and the uptake of potassium by the plant.
- Influence of cultivar practices: takes into account, in particular, the effect of organic fertilization and its influence with the soil’s own microorganisms.
- Influence of oenological factors and of the evolution of acid-base balance during winemaking: includes the study of the acid metabolism of the species that participate in alcoholic and malolactic fermentation. The project considers a trunk line that revolves around the use of unconventional yeast species for the acidification of musts and wines.