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The texture parameters of three red grape varieties (Mencía, Brancellao, and Merenzao) cultivated in Galician vineyards (North-West Spain) were determined. Different ripening stages (A: 176 ± 8 g/l reducing sugars; B: 193 ± 8 g/l reducing sugars; C: 210 ± 8 g/l reducing sugars; D: 227 ± 8 g/l reducing sugars) were also considered. Principal component analysis was performed for a better understanding of the differences found among grapes according to variety and ripening stage based on the skin and berry texture parameters. The parameters differentiating varieties were the skin break force and energy measured on the lateral side, whereas ripening stages can be classified on the basis of berry cohesiveness. The hardest berry skin was associated with the Merenzao variety with skin break force values comprised between 0.752-0.811 N and skin break energy between 0.715-0.790 mJ for A and B ripening stages, respectively. Instead, Brancellao variety presented the softest skin with skin break force values ranging from 0.521 to 0.562 N and skin break energy from 0.407 to 0.475 mJ for A and B ripening stages, respectively. Ripeness grade increased with the berry cohesiveness for all the varieties studied.

Genetic diversity of wine Saccharomyces cerevisiae strains involved in spontaneous fermentations was studied by analysis of mitochondrial DNA restriction patterns. Yeasts were isolated at different stages of fermentations with must from three different white grapevine varieties, Albariño, Godello and Treixadura, which are autochthonous from Galicia. Nineteen different patterns out of a total of 446 strains analysed were identified, but only a few of them appeared at high frequency and therefore were able to lead the fermentation process. Some strains were common to all fermentations; however, most of them were a minority being only found at low frequency for one or two specific grape varieties. The dominant strain was different for each variety except in one case, suggesting that some strains are better adapted to certain must conditions.

Inoculation of active dry yeasts during the wine-making process has become a common practice in most wine-producing regions; this practice may affect the diversity of the indigenous population of Saccharomyces cerevisiae in the winery. The aim of this work was to study the incidence of commercial yeasts in the experimental winery of Estación de Viticultura e Enoloxía de Galicia (EVEGA) and their ability to lead spontaneous fermentations. To do this, 64 spontaneous fermentations were carried out in the experimental cellar of EVEGA over a period of 7 years. Samples were taken from must and at the beginning, vigorous and final stages of fermentation. A representative number of yeast colonies was isolated from each sample. S. cerevisiae strains were characterised by analysis of mitochondrial DNA restriction patterns. The results showed that although more than 40 different strains of S. cerevisiae were identified, only 10 were found as the dominant strain or in codominance with other strains in spontaneous fermentations. The genetic profiles (mtDNA-RFLPs) of eight of these strains were similar to those of different commercial yeasts that had been previously used in the EVEGA cellar. The remaining two strains were autochthonous ones that were able to reach implantation frequencies as high of those of commercial yeasts. These results clearly indicated that commercial wine yeasts were perfectly adapted to survive in EVEGA cellar conditions, and they successfully competed with the indigenous strains of S. cerevisiae, even during spontaneous fermentations. On the other hand, autochthonous dominant strains that presented desirable oenological traits could be of interest to preserve wine typicity.

XG3, an autochthonous strain of S. cerevisiae, constitutes a useful tool to elaborate wines with singular characteristics.

Monovarietal grape pomace distillates (orujo) of six native varieties of Vitis vinifera L. from Galicia (Albarino, Treixadura, Godello, Loureira, Dona Branca, and Torrontes) have been thoroughly analyzed considering esters, alcohols, major aldehydes, monoterpenes, sesquiterpenes, norisoprenoids, and diterpenes. Albarino and Loureira distillates showed similar profiles of terpenic compounds, with the Loureira products having higher contents of monoterpenols. Native Torrontes distillate from Galicia is principally characterized by marked levels of some sesquiterpenes such as cadinene isomers and epizonarene. On the other hand, Treixadura, Godello, and Dona Branca grape pomace distillates seem not to have any marked terpenic content, and their single separation is difficult. PCA data treatments showed a good separation among the terpenic-rich varieties. Also, the p-menthen-9-al isomers, typical flavors in honey citrus and dill herb (derived from 8-hydroxylinalool), are reported for the first time in grape pomace distillate.