Impact of Metschnikowia pulcherrima and Saccharomyces cerevisiae in mixed fermentation on volatile compounds and energy sustainability in Lugana wine

Abstract

In recent years, heightened awareness of the environmental impact has led to sustainability as a key issue for the winemaking sector. During white wine production, the primary process affecting wineries’ energy consumption is temperature control during fermentation (de Castro et al, 2024). Since the fermentation temperature substantially influences yeast metabolism and aroma retention in the final product, we evaluated the effects of high (20°C) and low (16°C) temperatures and multistarter fermentations on the volatile profile of Lugana wine. Indeed, Giovenzana et al (2016) demonstrated that using selected yeasts at higher temperatures fermentation could reduce the energy requirements by 65 %. Furthermore, Castrillo et al (2019) indicated the oenological potential of non-Saccharomyces yeasts to mitigate the effects of climate change in winemaking. These findings can help develop new strategies for sustainability. In this context, we conducted micro-fermentation trials using two commercial strains of Metschnikowia pulcherrima (Level² Flavia and Level² Initia) and Saccharomyces cerevisiae EC 1118 in a natural thiol-rich white must from Trebbiano variety. The M. pulcherrima strains were mainly selected for their remarkable β-glucosidase and β-lyase activities, which can significantly enhance the aromatic complexity of wines, increasing the terpene and thiols contents (Binati et al, 2020). Each M. pulcherrima strain was inoculated at the beginning of fermentation and S. cerevisiae 48 h later. A single inoculum of S. cerevisiae was used as a control. The sequential fermentations and the control conducted at 20°C finished faster (within 11 days) than at 16°C, which concluded the process in 16 days. The wines obtained at the two temperatures differed in their concentration of volatile compounds, showing marked differences in esters, thiols, and alcohols content. Differences were also detected by sensory analysis. Wines fermented at 20°C showed more intense tropical and fruity aromas due to a significantly higher thiol content, while higher levels of ethyl esters and fatty acids characterized those at 16°C. The temperature had a more pronounced impact on the volatile compounds of wine than the specific M. pulcherrima strain used. However, sequential fermentations at 20°C led to significantly higher thiol concentrations than the control singly inoculated with S. cerevisiae. In conclusion, using M. pulcherrima with S. cerevisiae at higher, non-traditional temperatures modulates the aromatic compounds, giving remarkable differentiation of wines while improving energy efficiency and supporting more sustainable winemaking practices.

Funding

This study was financially supported by the Italian Ministry of Agriculture, Food Sovereignty and Forestry (MASAF), project WINERED, Innovative interdisciplinary approaches for reducing the environmental impact of vinification.