Modulation of a defined community of Oenococcus oeni strains by Torulaspora delbrueckii and its impact on malolactic fermentation

Abstract

Background and Aims: Torulaspora delbrueckii is being used increasingly as a starter for alcoholic fermentation (AF) because of its chemical modulation of wine. Previous studies on this yeast in a natural must have shown a different Oenococcus oeni population by the end of MLF. In this study we aim to evaluate this aspect in a defined O. oeni strain consortium in a sterile grape must during winemaking. Methods and Results: Before commencing AF with either S. cerevisiae or both T. delbrueckii and S. cerevisiae, the must was inoculated with a defined population of O. oeni strains. The use of T. delbrueckii determined the bacterial population at the end of MLF. Also, the inoculation of a selected strain after AF produced wines with different chemical composition to those fermented with the initial bacterial community. Conclusions: Different yeast inoculation strategies modulate the O. oeni population, and this has an impact on the chemical composition of the wines. Moreover, the inoculation of a small O. oeni population in must leads to a process similar to spontaneous MLF. Significance of the Study: Torulaspora delbrueckii can be used as a tool to modulate the O. oeni population and enhance the aromas related to MLF.