Impact of Lachancea thermotolerans on chemical composition and sensory profiles of Merlot wines

Impact of <i>Lachancea thermotolerans</i> strain and lactic acid concentration on <i>Oenococcus oeni</i> and malolactic fermentation in wine

“…This study confirmed the strain-specific performance of sequential inoculations of L. thermotolerans strains, which corresponded to their characterisation in pure cultures (Hranilovic et al, 2018) and co-cultures (Hranilovic et al, 2021), alike. In particular, a large variation in L-lactic acid production (and the consequent pH/TA modulation) was observed across the strains studied here (Figure 6).…”

“…Besides a marked effect on wine acidification, Merlot wines also differed in ethanol content, with up to 1.1 % v/v less ethanol in the LT than the SC control wines (Table 2). All inoculated wines produce similar amounts of acetic acid and glycerol, while the total SO 2 only increased in the SC control, remaining constant or decreasing in L. thermotolerans inoculations, as observed previously (Benito et al, 2016;Hranilovic et al, 2021). Post-AF, Sauvignon blanc wines were sequentially inoculated for MLF with and without pH standardisation, while both co-and sequential inoculation of LAB were investigated in Merlot.…”

“…Importantly, from the winemakers' perspective, chemical and sensory profiling of wines co-fermented with L. thermotolerans revealed positive characteristics as compared to their respective S. cerevisiae controls, including lower concentrations of ethanol, total SO 2 , and volatile acidity, and higher concentrations of ethyl esters and terpenes (Benito et al, 2016;Binati et al, 2020;Hranilovic et al, 2018). These sequentially fermented wines were also described by tasters as being "fresher" and "crisper" than wines fermented with S. cerevisiae controls (Hranilovic et al, 2021). Following the substantial research on the use of L. thermotolerans as starter cultures, several strains are now commercially available for winemaking (Roudil et al, 2020).…”

“…This occurs via lactate dehydrogenase activity from pyruvate obtained through glycolysis (breakdown of sugars) and thus is an alternative pathway to ethanol production (Hranilovic et al, 2017;Sgouros et al, 2020). Concomitant decreases in ethanol content represent another potential benefit of L. thermotolerans modalities, as warm-climate wines are often overly alcoholic (Hranilovic et al, 2021). However, L-lactic acid production varies between L. thermotolerans strains, ranging from negligible in some to over 10 g/L in others, although the molecular mechanisms of these differences is still under investigation (Hranilovic et al, 2018;Sgouros et al, 2020).…”

“…One challenge in using L. thermotolerans is its inability to complete fermentation in grape juice (Hranilovic et al, 2018;Morata et al, 2018), therefore requiring either co-inoculation or sequential inoculation with S. cerevisiae or other robust yeast to reach dryness. Of the two strategies, sequential inoculation generally results in a greater impact of L. thermotolerans on wine chemical composition, including acidification (Gobbi et al, 2013;Hranilovic et al, 2021). Importantly, from the winemakers' perspective, chemical and sensory profiling of wines co-fermented with L. thermotolerans revealed positive characteristics as compared to their respective S. cerevisiae controls, including lower concentrations of ethanol, total SO 2 , and volatile acidity, and higher concentrations of ethyl esters and terpenes (Benito et al, 2016;Binati et al, 2020;Hranilovic et al, 2018).…”