Modulation of a defined community ofOenococcus oenistrains byTorulaspora delbrueckiiand 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.

Effect of Deacidification Treatment on the Flavor Quality of Zaosu Pear–Kiwifruit Wine

“…This indifference may be attributed to the different responses of individual compounds ( Supplementary Table S5 ) to biosynthesis and esterification during MLF. Octanoic acid was the most abundant fatty acid in all wines, with the highest concentration (341 µg/L) in MLF wine ( Table 4 ), in agreement with previous reports [ 12 , 36 ]. Octanoic acid decreased by 79.2% after chemical deacidification and, consequently, the total fatty acid content decreased.…”

The use of Torulaspora delbrueckii to improve malolactic fermentation

“…This phenomenon may help to develop MLFs in difficult wines, promoting the development of different O. oeni strains and preserving the impact of the autochthonous microbiota on the wine organoleptic profile. Nevertheless, the population modulation of T. delbrueckii seems to be strain specific (Balmaseda et al, 2022a ).…”

“…During AF, yeasts can also produce significant amounts of acids that can reduce the pH value from must to wine. The effect of T. delbrueckii on pH value reports heterogeneous results (Figure 2C ) because the same strain, for instance, Viniferm (Agrovin S.A.), can increase it (Balmaseda et al, 2021b , 2022a ; Belda et al, 2015 ) or decrease it (Balmaseda et al, 2021b ; Belda, Ruiz, Beisert, et al, 2017 ) depending on the medium. Nevertheless, high variations have not been reported that may have a significant impact on O. oeni (Table 2 ), with the exception of Martín‐García et al ( 2020 ), who reported a pH increase of 0.48 with the use of T. delbrueckii in sequential inoculation with S. cerevisiae .…”