To a better understanding of the stuck fermentation during spontaneous fermentation due to microbial interactions and the chemical composition of the must
Final Report Abstract
The goal of this project was to gain more information about unconventional reasons for stuck fermentations and hints for overcoming this problem. During this work, it could be shown that Saccharomyces bayanus was the dominant wine yeast in this winery instead of the classic wine yeast S. cerevisiae. During stuck fermentation, a triple hybrid S. cerevisiae x kudriavze-vii x bayanus grew and finished fermentation. Both isolated yeast strains, S. bayanus and S. cerevisiae x kudriavzevii x bayanus, were able to use glucose and fructose from the beginning and were able to grow at low temperatures of 15 ºC and in the absence of yeast assimilable nitrogen in the form of ammonium sulfate as long as amino acids were present in the medium, in contrast to S. cerevisiae. Chemical investigations revealed that yeast assimilable nitrogen was very limited in the must from the cooperative winery, with a maximum of 160 mg/L at the beginning of the fermentation. For that reason, both isolated yeast strains are interesting as starter cultures. It may also explain why S. cerevisiae is not the main fermenting yeast in this winery. The triple hybrid S. cerevisiae x kudriavzevii x bayanus is able to use fructose even more efficiently than S. bayanus and is less dependent on the amino acid concentration of the medium. This strain has already been successfully used during this project to restart fermentation in the winery from which it was isolated. Saccharomyces hybrids have already been described as being involved in winemaking, but their role in overcoming stuck fermentations has not yet been mentioned. These results can be useful to avoid or overcome stuck fermentation with the selective use of these yeast strains. The cooperative winery, which is placed in the upper quality segment, has had problems with stuck fermentation every year. Therefore, the application of the triple hybrid S. cerevisiae x kudriavzevii x bayanus is a great opportunity to avoid stuck fermentations and financial losses without using commercial starter cultures or other common practices which can lead to a change in the aroma profile. One of the biggest challenges during this project was to combine our scientific interest and the winery practices. It was not possible, for example, to predict which casks would show stuck fermentation and whether microbial analysis could not be performed during the complete fermentation in this case. Other casks were selected for coupage by the winemaker and, therefore, could not be left in stuck fermentation until it was possible for the the hybrid to grow and finish fermentation. For that reason, some experiments were relocated from the wine cellar and performed at our institute. It was assumed at the beginning of the project that the stuck might be caused by some kind of inhibitor or microbial interaction. At that time, it was not expected that other Saccharomyces species play such an important role in facing and overcoming stuck fermentation in the winery instead of the classic wine yeast Saccharomyces cerevisiae. For that reason, the focus was placed on these isolated yeast strains in the third year of the project after studying succession for two years.
Publications
- (2013). Differentiation of species of the genus Saccharomyces using biomolecular fingerprinting methods. Applied Microbiology and Biotechnology 97, 4597-4606
Blättel, V., Petri, A., Rabenstein, A., Kuever, J., König, H.
(See online at https://doi.org/10.1007/s00253-013-4823-z) - (2013). Differenzierung von Weinhefen der Gattung Saccharomyces: Relevanz für die Verwendung von Starterkulturen. Deutsches Weinbau-Jahrbuch 2014, 160-169
Petri, A., Christ, E., Blättel, V., Rabenstein, A., Kuever, J., König, H.
- (2013). Do thaumatin-like proteins in wine influence its flavor profile? Deutsche Lebensmittel-Rundschau: 109, 319-323
Pfeiffer, P., Kreubel, J., Christ, E., König, H.
- (2014). Studies on two exoenzymes which lyse wine-spoiling bacteria. Advances in Microbiology 4, 527-538
Sebastian, P., Claus, H., König, H.
(See online at https://dx.doi.org/10.4236/aim.2014.49059) - (2014). Wickerhamomyces anomalus AS1: a new strain with potential to improve wine aroma. Annals of Microbiology 64, 483-491
Sabel, A., Martens, S., Petri, A., König, H., Claus, H.
(See online at https://doi.org/10.1007/s13213-013-0678-x) - An Exemplary Model Study for Overcoming Stuck Fermentation during Spontaneous Fermentation with the Aid of a Saccharomyces Triple Hybrid. Journal of Agricultural Science; Vol. 7, No. 8; 2015, pp. 18-34
Christ, E., Kowalczyk, M., Zuchowska, M., Claus, H., Löwenstein, R., Szopinska-Morawska, A., Renaut, J., König, H.
(See online at https://dx.doi.org/10.5539/jas.v7n8p18)
