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

Genetic diversity of the grapevine (Vitis vinifera L.) cultivars most utilized for wine production in Portugal

Portugal is very rich in grapevine biodiversity but nowadays only a small number of cultivars (13 black and 3 white) with defined enological characteristics are being used. However, there are still 51 cultivars with significant expression in the country which have a great potential to be used in the establishment of new vineyards. Considering the importance of identifying and understanding the genetic relatedness of the main cultivars used for wine making in Portugal, those cultivars were genotyped with the 6 SSRs loci VVMD5, VVMD7, VVMD27, VrZag62, VrZag79 and VVS2 that are recommended by the Office de la Vigne et du Vin for the elaboration of the worldwide database containing the alleles of all the known grapevine cultivars. A total of 49 alleles were detected with an average allele number of 8.17 per locus. The SSR profile of the 51 cultivars, at the 6 evaluated loci, indicates that all can be distinguished from each other. In addition, this study produces information on the relationship of these 51 grapevine cultivars with cultivars of other important Mediterranean wine producing regions

<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

Untargeted Metabolomics Discriminates Grapes and Wines from Two Syrah Vineyards Located in the Same Wine Region

The influence of terroir in determining wine sensory properties is supported by the specific grape microbiome and metabolome, which provide distinct regional wine characteristics. In this work, the metabolic composition of grapes, must and wine of the Syrah grape variety cultivated on two sites in the same region was investigated. Concomitantly, a sensorial analysis of the produced wines was performed. Ultra-high-resolution liquid chromatography coupled with tandem mass spectrometry (UHPLC-Q-ToF-MS/MS) was applied to identify grape and wine metabolites. Untargeted metabolomics was used to identify putative biomarkers for terroir differentiation. More than 40 compounds were identified, including 28 phenolic compounds and 15 organic acids. The intensity evolution of the analyzed chemical compounds showed similar behavior during the fermentation process in both terroirs. However, the metabolic analysis of the grape, must and wine samples enabled the identification of an anthocyanin, chrysanthemin, as a putative biomarker of terroir 1. The overall sensorial quality of the wines was also evaluated, and according to the hitherto reported results, the wines from site 1 scored better than the wines from site 2. The results highlight the potential of metabolomics to assess grape and wine quality, as well as terroir association