Author(s):
Vilela, Alice 
; Schuller, Dorit ; Mendes-Faia, Arlete ; Côrte-Real, Manuela
Date: 2008
Persistent ID: http://hdl.handle.net/10348/1426
Origin: Repositório da UTAD
Subject(s): Saccharomyces cerevisiae, Wine, Volatile acidity, Refermentation, Acetic acid
Description
The main goal of this study was to isolate and characterize wine yeasts with ability to reduce volatile acidity of wines, using a refermentation process. From a set of 135 yeast isolates, four strains revealed ability to use glucose and acetic acid simultaneously. Three of them were identified as Saccharomyces cerevisiae and one as Lachancea thermotolerans by sequencing the D1/D2 domain of the 26S ribosomal DNA large subunit. Microsatellite analysis shows, that S. cerevisiae strains 30C and 45C are genetically very similar.
With the purpose to further evaluate whether the ability to degrade acetic acid in the presence of glucose was a characteristic of the isolated strains, nine commercial S. cerevisiae strains were chosen for further analysis, from this group, strains S29 S30 an and S29 showed the most similar behavior and therefore included in further experiments. In two culture media containing acidic wines with high glucose/low ethanol or low glucose/high ethanol concentrations, the S. cerevisiae strains showed an initial simultaneous consumption pattern of glucose and acetic acid under both aerobic and limited aerobic conditions, independently of the relative amounts of glucose and ethanol. In a medium containing low glucose/high ethanol, under aerobic conditions, S26 was the most efficient acid degrading strain .These results suggest that under aerobic conditions Saccharomyces strains are less affected by the higher ethanol concentration. But, in a refermentation process with low oxygen availability, and with high glucose/low ethanol initial concentrations, the Saccharomyces strain S29 was the most efficient strain. Under these same limited-aerobic conditions but in a medium containing initial low glucose/high ethanol all Saccharomyces strains studied display acetic acid degradation efficiencies identical to Z. bailii ISA 1307.
Our results also showed that S. cerevisiae can decrease volatile acidity of wines with an elevated content of acetic acid, even without the addition of a sugar source under limited oxygen conditions.
