Monitoring of qualitative parameters of red wine from the Nitra winegrowing region in Slovakia using the method of simultaneous sugar and malic acid fermentation

The experiment dealt with the different procedures for malic acid degradation in red wine using the malolactic fermentation (MLF) process, its influence on qualitative parameters, and the formation of undesirable acetic acid in wine in the vintages of 2020 and 2021. We used the “Cabernet Sauvignon” variety, active dry Saccharomyces cerevisiae yeast and pure culture of the Oenococcus oeni malolactic bacteria. We found that MLF by noble, selected cultures can take place simultaneously when fermentable carbohydrates are present without significantly increasing acetic acid levels. All inoculation variations reached final acetic acid values of 0.807–0.820 g/L in 2020 and 0.753–0.780 g/L in 2021. The control variations without inoculation had the highest acetic acid values, which were 0.897 g/L (2020) and 0.803 g/L (2021) at the end of fermentation. In 2021, the control variant proved inadequate, leaving 0.53 g/L of malic acid in the wine. The duration of fermentation was shortened by simultaneous co-inoculation of yeast and malolactic bacteria without affecting unwanted acetic acid. During this process, it is, in addition to monitoring acetic acid, extremely important to control the pH value, which must be lower than 3.5. The alternative of using MLF as a technology involving the co-inoculation of yeast and malolactic bacteria starter culture without a negative impact on the wine’s quality proved to be suitable and effective.