Mixed fermentation with Metschnikowia pulcherrima using different grape varieties

The study and use of non-Saccharomyces yeasts to wine improvement and diversification has gained considerable relevance in recent years. The present work reports a pilot-scale winery assay of mixed fermentation with a commercial strain of Metschnikowia pulcherrima, tested in five white and nine red grape varieties. Two modalities were assayed, one with the addition of M. pulcherrima at time zero and addition of Saccharomyces cerevisiae after 24 h, and a control using only S. cerevisiae at time zero. Fermentation was monitored by daily measurement of density and temperature. Wine physicochemical analysis was performed after winemaking and repeated after four years of aging. Variance and multivariate analysis were used to examine these data. Triangle and ranking tests were performed on the wines obtained, using an experienced sensory panel. Alcoholic fermentation proceeded smoothly until there was complete consumption of the sugars. M. pulcherrima in mixed fermentation, although mainly recommended for white wine, was also tested for red wines. These wines generally presented higher glycerol, reducing sugars and total dry matter, and lower alcohol content, in line with the current market trend. Significant sensory di erences among modalities were only obtained for three varieties. Results emphasized that grape variety is a relevant factor in studies with non-Saccharomyces yeastsinfo:eu-repo/semantics/publishedVersio

<i>Saccharomyces cerevisiae</i> Diversity in <i>Arbutus unedo</i> L. Fermentations in Association with the Volatile and Sensory Similarities of the Distillates

The fermentation of Arbutus unedo L. fruit is traditionally carried out in the production of spirits. The present study followed the spontaneous fermentation of A. unedo fruit harvested in October and December 2019 by two producers from the central region of Portugal. The microbiota was studied, and although a great diversity of indigenous yeasts was found, S. cerevisiae isolates could still be grouped into eight clusters, and a good separation between producers was achieved. Based on the results of a multivariate analysis of the physical-chemical and volatile composition of the distillates, a distinction between the distillates from the two producers was determined. Moreover, these findings are corroborated by the similarities in flavor that were found. Along with the variability found in the distillates, S. cerevisiae isolates could be clustered and associated with each producer. On the other hand, the differentiation of the harvesting period was not so clear. The characterization of the indigenous yeasts associated with the fermentation process of Arbutus unedo L. fruit can serve as an important contribution to the preservation of the specific characteristics of its distillates