Permanence of yeast inocula in the winery ecosystem and presence in spontaneous fermentations

The oenological practice of systematic inoculation with active dried yeasts is commonly used by many wineries around the world. However, the use of these yeasts is not free from controversy, since this practice has occasionally been described as having a negative effect on the biodiversity of natural yeast present in the wineries. The purpose of this study is to analyse the presence of commercial yeasts used as inocula in the ecosystem of three D.O.Ca. ("Qualified" Designation of Origin) Rioja wineries. It studies the permanence of these yeasts in winery equipment and their participation in spontaneous fermentations where they have not been used for inoculation. The results indicate that the presence of the active dry yeasts used in the wineries was scarce or non-existent, both in the ecosystem of each winery and in the spontaneous fermentations where they had not been added. So, repeated inoculation with active dry yeasts allowed a high presence and development of autochthonous (Saccharomyces and non-Saccharomyces) yeasts, both in equipment and in the spontaneous fermentations carried out.