Screening of yeast mycoflora in winery air samples and their risk of wine contamination

The airborne yeast flora associated with four different areas in 3 Spanish wineries was analyzed over the course of a year (winter, spring, summer and fall) in order to distinguish the yeast species present in this ecosystem and to evaluate the risk of air as a means of wine contamination by spoilage yeasts. Sampling was conducted in the vinification, bottling, cask aging and bottle aging areas. 367 yeasts were identified from two different culture media: 258 in a generic medium for yeast species and 109 in a more selective medium for the Brettanomyces/Dekkera genus.Low levels of yeasts were found in the air with different values depending on the activity being performed at the time: the population in the bottling area increases when bottling is being carried out, and it also increases in the air present in the winemaking premises during vinification. Most of the isolated yeasts were members of the non-Saccharomyces group. Yeasts from the Saccharomyces cerevisiae species were only detected in the air present in the vinification area during the vinification period. Aureobasidium and Cryptococcus were the dominant genera in the air and they were found permanently in the 3 wineries in every area analyzed. The highest level of yeast cells was found in the bottling line, which makes it the area in the winery that requires the greatest vigilance. However, the types of yeast detected are not a real risk to the quality of the wine being bottled. Spoilage yeast Brettanomyces/Dekkera was detected in the air present in the cask area of one winery when wine containing these yeast species was being handled. This suggests that air can be a means for these yeast cells to spread in the wineries and that yeast dissemination is associated with the handling of the wine containing them.No significant differences were found between the wineries, neither in the count of yeasts in the air nor in the main genera present. Therefore, this data establishes an initial description of the yeast levels in the air, the genera and species usually present and the risk to the stability of the wine and its spoilage.