Transient acetaldehyde production by SO2 producing S. cerevisiae promotes survival of Oenococcus oeni during co-fermentation

Stuck or sluggish malolactic fermentation (MLF) can be problematic in limiting wine conditions, particularly white and sparkling base musts / wines. In these cases, knowledge of yeast-bacteria strain compatibility and the amount of sulfur dioxide (SO2) a yeast strain produces are important considerations for successful MLF.
Here, the effects of yeast-derived SO2 production on O. oeni survival was investigated in laboratory- and pilot-scale co-fermentations in Chardonnay. Further to the S. cerevisiae strain affecting O. oeni survival and MLF, we show that SO2 production by yeast (to approximately 65 mg/L) can be uncoupled from O. oeni survival in early stages of co-fermentation. Bacterial survival with certain SO2-producing yeast strains was correlated with early, transient formation of a high concentration of acetaldehyde.  Upon co-inoculation, an extremely low concentration range (approximately 1–44 µg/L) of calculated molecular SO2 is indicated to regulate O. oeni survival. Possible s..., ,