Effects of acetic acid, ethanol and SO2 on the removal of volatile acidity from acidic wines by two Saccharomyces cerevisiae commercial strains

Abstract

Herein we report the influence of different combinations of initial concentration of acetic acid and ethanol on the removal of acetic acid from acidic wines by two commercial Saccharomyces cerevisiae strains S26 and S29. Both strains reduced the volatile acidity of an acidic wine (1.0 g l-1 acetic acid and 11% (v/v) ethanol) by 78% and 48%, respectively. Acetic acid removal by both strains was associated with a decrease in ethanol concentration of about 0.7 – 1.2% (v/v). Strain S26 revealed better removal efficiency due to its higher tolerance to stress factors imposed by acidic wines. We also demonstrate that the strong anti-oxidant and antiseptic effect of sulphur dioxide (SO2) concentrations up to 170 mg l-1 inhibit the ability of both strains to reduce the volatile acidity of an acidic wine under our experimental conditions. Therefore, deacidification should be carried out either in wines stabilized by filtration or in wines with SO2 concentrations below 75 mg l-1. Deacidification of wines with the better performing strain S26 was associated with changes in the concentration of volatile compounds. The most pronounced increase was observed for isoamyl acetate (banana) and ethyl hexanoate (apple, pineapple), with an 18- and 25-fold increment, respectively, to values above the detection threshold. The acetaldehyde concentration of the deacidified wine was 2.3 times higher, and may have a detrimental effect on the wine aroma. In addition, deacidification led to increased fatty acids concentration, but still within the range of values described for spontaneous fermentations, and with apparently no negative impact on the organoleptical properties. We propose the use of S. cerevisiae strain S26 for the efficient reduction of the volatile acidity from acidic wines with acetic acid and ethanol concentrations not higher than 1.0 g l-1 and 11% (v/v), respectively.