Winetech Technical Yearbook 2022

NOVEMBER

SHUTTERSTOCK

Adding freshness back to wine with Level 2 Laktia ™

INTRODUCTION With the increase in alcohol levels and loss of acidity and freshness due to climate change, acidifying wines with different acids of chemical origin is common. This acidification has some limitations in terms of legislation (even banned in some appellations) and also in terms of impact (from an acidification point of view and also from a sensory one). A new natural way to increase freshness and acidity is now available for winemakers with the use of Level 2 Laktia™ Lachancea thermotolerans. This non fermenting non- Saccharomyces yeast found in the must environment naturally acidifies the wines when converting sugars into lactic acid. Lowering the wine pH will also help with the efficiency of SO 2 and help reduce its use. ANN DUMONT & MARION BASTIEN I Why Lachancea thermotolerans ? Lachancea thermotolerans ( L. thermotolerans ) is a ubiquitous yeast species found worldwide, in anthropic and wild habitats (Hranilovic et al ., 2017), including the grape and wine ecosystem. It is found in the must and wine environment, but cannot complete wine fermentation alone, mainly because of high oxygen needs (Holm Hansen et al ., 2001; Petitgonnet et al ., 2019) and limited resistance towards ethanol. A sequential inoculation with a fermenting yeast, Saccharomyces cerevisiae , is essential to complete fermentation. The main technological interest of L. thermotolerans inoculation during wine fermentation is its ability to lower the pH in wine

BY AMANDINE DEROITE, ANNE ORTIZ-JULIEN, ANTHONY SILVANO, JOSÉ MARIA HERAS,

(Comitini et al ., 2011; Morata et al ., 2019; Vaquero et al ., 2020). This acidification is due to lactic acid production from pyruvate through a reaction catalysed by three lactic acid dehydrogenases LDH1, 2 and 3 (figure 1). This carbon metabolism is “competing” with ethanol production, slightly decreasing the final alcohol content and is dependent on the L. thermotolerans strain and the fermentation conditions. In addition to freshness improvement, L. thermotolerans inoculation during wine fermentation can lead to higher glycerol production, impacting the mouthfeel (Comitini et al ., 2011; Gobbi et al ., 2013), with significant heterogeneity between strains among this species. L. thermotolerans inoculation also generally leads to higher ester production (ethyl lactate and ethyl acetate) and 2-phenyl ethanol (Comitini et al ., 2011; Gobbi et al ., 2013; Morata et al ., 2019; Sgouros et al ., 2020; Hranilovic et al ., 2021) with some differences between strains both in terms of ester compounds and concentration. Hranilovic et al . (2021) have also shown an increase in linalool liberation, consistent with L. thermotolerans β-glucosidase activity as described by Comitini et al . (2011). There is high variability among L. thermotolerans strains. For example, in the same matrix (wine conditions), lactic acid production can vary from strain to strain (Hranilovic et al ., 2018). Sgouros et al . (2020) and Gatto et al . (2020) have shown that high lactic acid producers present a higher LDH2 expression than low lactic acid producers. Selection and characterisation of Lachancea thermotolerans Level 2 Laktia™ Lachancea thermotolerans Level 2 Laktia™ was selected in the

64

WINETECH TECHNICAL YEARBOOK 2022