Yeast and bacterial inoculation practices influence the microbial communities and sensory profiles of barrel-fermented Chardonnay wines

Microbial communities during alcoholic fermentation (AF) and malolactic fermentation (MLF) can affect the sensory attributes of the finished wine. When MLF is desired, it is common to initiate AF by inoculating Saccharomyces cerevisiae, followed by inoculation with Oenococcus oeni. In this study, fresh grape must was subjected to a combination of inoculation treatments with S. cerevisiae and O. oeni. Bacterial and yeast community dynamics, and S. cerevisiae and O. oeni populations, were monitored using culture-dependent and culture-independent technologies. The sensory profiles of the finished wines were evaluated by a panel of experts. Yeast inoculation affected the yeast community and the S. cerevisiae population; wines left uninoculated had a higher diversity of S. cerevisiae strains and contained more Torulaspora delbrueckii. At the end of MLF, the inoculated O. oeni strain dominated the treatments to which it was added, but the wines that were not inoculated contained unique assemblages of O. oeni strains, including potentially indigenous strains. Wines that fermented uninoculated were rated higher in intensity for most sensory attributes, including tropical fruit, butter, and vanilla. These results highlight the importance of relating wine sensory attributes to the fungi and bacteria present in the wine, at both the species and strain levels. For R-scripts and raw data files, please visit https://osf.io/zdva7/