Evaluation of Autochthonous Non-Saccharomyces Yeasts by Sequential Fermentation for Wine Differentiation in Galicia (NW Spain)

Abstract

Non-Saccharomyces yeasts constitute a useful tool in winemaking because they secrete hydrolytic enzymes and produce metabolites that enhance wine quality; in addition, their ability to reduce alcohol content and/or to increase acidity can help to mitigate the effects of climatic change on wines. The purpose of this study was to evaluate the oenological traits of non-Saccharomyces yeast strains autochthonous from Galicia (NW Spain). To do that, we carried out sequential fermentation using 13 different species from the yeast collection of Estación de Viticultura e Enoloxía de Galicia (Evega) and Saccharomyces cerevisiae EC1118. The fermentation kinetics and yeast implantation were monitored using conventional methods and genetic techniques, respectively. The basic chemical parameters of wine were determined using the OIV official methodology, and the fermentative aroma compounds were determined by GC–FID. The results evidenced the limited fermentative power of these yeasts and the differences in their survival after the addition of S. cerevisiae to complete fermentation. Some strains reduced the alcohol and/or increased the total acidity of the wine. The positive effect on sensory wine properties as well as the production of desirable volatile compounds were confirmed for Metschnikowia spp. (Mf278 and Mp176), Lachancea thermotolerans Lt93, and Pichia kluyveri Pkl88. These strains could be used for wine diversification in Galicia.

Characterization of Indigenous Non-Saccharomyces Yeast Strains with Potential Use in Winemaking

“…Some authors have proposed different mechanisms in the relationships between S. cerevisiae and non-Saccharomyces [18,51,52]. In this sense, the NS+XG3 group showed the highest concentration of volatile compounds, which have confirmed that native strains can improve the chemical and sensory characteristics, and differentiation of wines in accordance with numerous recent studies [3,30,[53][54][55]. In contrast, compounds accounting for acidity in the biplot are concentrated in the area of NS+EC1118 wines.…”

“…4). These concentrations are lower than 300 mgꞏL −1 , above which the aromas become undesirable, although the wines from pure culture fermentations achieved lower content of higher alcohols than those obtained for the same strains tested in sequential fermentations [29,30]. In addition, all the yeast species evaluated produced lower concentrations of these volatiles in the wines than S. cerevisiae, being L. thermotolerans the non-Saccharomyces species that produced the highest concentration of higher alcohols, in some cases doubling the concentration generated by Starm.…”

“…In addition, a weighting was added for each parameter, giving a higher relative score according to its relative importance depending on the standards required by these regulatory councils. The best rated native strain for each species was selected and its oenological potential was further evaluated in sequential fermentation with autochthonous strain S. cerevisiae XG3 and with a commercial strain (S. cerevisiae EC1118) as reported in [29,30]. In addition, Principal Component Analysis (PCA) was used to separate the wines according to basic chemical and volatile composition.…”

“…species were Lt93, Td315, Sb474 and Mf278, respectively. These strains were evaluated in sequential fermentation with the autochthonous S. cerevisiae strain XG3 [29] and with the commercial strain S. cerevisiae EC1118 [30].…”

Pre-Fermentative Cold Maceration and Native Non-Saccharomyces Yeasts as a Tool to Enhance Aroma and Sensory Attributes of Chardonnay Wine

“…The sequential fermentation of M. pulcherrima B-5 with S. cerevisiae QA23 did not significantly affect the ethanol content in both processes with and without maceration. Although it is considered that M. pulcherrima can produce wines with low ethanol content [18], there are some reports in which this strain did not affect the ethanol content [32] and good fermentation potential of M. pulcherrima was stated [9]. This indicates that the ability of M. pulcherrima to reduce ethanol content can be strain-dependent [10].…”