Abstract
This paper has studied the success of implantation for 16 commercial active dry yeasts (ADYs) during industrial fermentation (30) and the impact of these yeasts during spontaneous fermentations (19) in 10 wineries from the Denomination of Origin "Vinos de Madrid" over two consecutive years. Yeasts strains were identified by molecular techniques, pulsed field electrophoresis and microsatellite analysis. According to these techniques, all the ADYs were different with the exceptions of two strains, L2056 and Rh, which showed the same karyotype and loci size. The results showed that inoculating fermentations with ADYs did not ensure their dominance throughout the fermentation; the implantation level of ADYs was above 80% in only 9 of the 30 commercial fermentations studied; while in 16 fermentations, the dominance of the inoculated ADYs was below 50%. The type of vinification with the best implantation results overall were those associated with red wine fermentations. ADYs affected spontaneous fermentations, although their impact was observed to decrease in the second year of the study. Therefore, specific adaptation studies are necessary before using commercial yeasts during the fermentation process. At the same time, a study was carried out on the frequency of commercial strains in IMIDRA's yeast collection, made up of strains isolated from spontaneous fermentations of the different areas and cellars since the beginning of the Denomination of Origin "Vinos de Madrid" in 1990. Six different ADYs were found with a frequency of less than 5%.