Screening native yeast and lactic acid bacteria from different Chilean cultivars: Potential species for production of reduced ethanol wines

The potential use of non-traditional yeast species opens new possibilities regarding wine flavor, aroma, texture and ethanol content. Low and reduced ethanol wines have attracted much interest, and research has led to novel techniques to reduce ethanol content, including the use of non-traditional yeast. The aim of this study was to characterize the natural microbiota (yeasts and lactic acid bacteria) observed during spontaneous fermentation of six grape varieties from the Maule Region (Chile). Thus, the fermentative potential of selected yeast isolates was determined in terms of sugar consumption and ethanol production. Isolates with potential for producing reduced ethanol wines were further studied in sequential inoculations with Saccharomyces cerevisiae. Nine non-Saccharomyces species belonging to seven genera were identified from the spontaneous fermentation, but only three lactic acid bacteria genera were identified. During final fermentation stages, S. cerevisiae and L. mesenteroides were dominant, while only Candida, Metchnikowia, Torulaspora, and Lachancea spp. were observed after 14 days of fermentation. Pure culture fermentation with selected isolates showed about 50% sugar utilization, with ethanol production ranging from 6.25 to 9.25% v/v. Regarding sequential inoculations, less than 2% of sugars remained after 10 days of fermentation, and significantly less ethanol was produced than in control samples. Our results suggest that native yeasts R. glutinis, M. pulcherrima and H. uvarum, isolated in this study, potentially serve to produce reduced ethanol wines. However, more studies on flavor and aroma contribution are needed.