WINETECH Technical Yearbook 2019

These results would have been a valuable add-on and would certainly add weight to the reasoning behind using this technique. The variable results obtained between different cultivars also indicate the strong influence of inherent must composition on the outcomes of this treatment and the expected favourable results may not be obtained depending on the specific matrix. SUMMARY They found significant differences in the concentrations of esters, higher alcohols, fatty acids, terpenes and volatile thiols. They also found the “wild” yeast used to be fructophilic and contributing to producing slightly less alcohol in the final wine. REFERENCES Belda, I., Ruiz, J., Esteban-Fernández, A., Navascués, E., Marquina, D., Santos, A. & Moreno-Arribas, M.V., 2017. Microbial cont r i but i on to wi ne aroma and i t s intended use for wine quality improvement. Molecules 22(2). https://doi.org/10.3390/ molecules22020189 .

Englezos, V., Torchio, F., Cravero, F., Marengo, F., Giacosa, S., Gerbi, V., Rantsiou, K., Rolle, L. & Cocolin, L., 2016A. Aroma profile and composition of Barbera wines obtained by mixed fermentations of Starmerella bacillaris (synonym Candida zemplinina ) and Saccharomyces cerevisiae. LWT – Food Science and Technology 73, 567-575. https:// doi.org/10.1016/J.LWT.2016.06.063 . Guérin-Schneider, R., Steyer, D., Caixach, J., Ballester, J., Sadoudi, M., Alexandre, H., Gallardo-Chacón, J-J., Rousseaux, S., Tourdot-Maréchal, R. & Vichi, S., 2012. Yeast- yeast interactions revealed by aromatic profile analysis of Sauvignon blanc wine fermented by single or co-culture of non- Saccharomyces and Saccharomyces yeasts. Food Microbiology 32(2), 243-253. https:// doi.org/10.1016/j.fm.2012.06.006 . Englezos, V., Rantsiou, K., Cravero, F., Torchio, F., Pollon, M., Fracassetti, D., Ortiz-Julien, A., Gerbi, V., Rolle, L. & Cocolin, L., 2018. Volatile profile of white wines fermented with sequential inoculation of Starmerella

bacillaris and Saccharomyces cerevisiae. Food Chemistry 257 (March), 350-360. https://doi. org/10.1016/j.foodchem.2018.03.018 . Eng l ezos , V. , Rant s i ou , K . , Cravero, F., Torchio, F., Ortiz-Julien, A., Gerbi, V., Rolle, L. & Cocolin, L., 2016B. Starmerella bacillaris and Saccharomyces cerevisiae mixed fermentations to reduce ethanol content in wine. Applied Microbiology and Biotechnology 100(12), 5515-5526. https:// doi.org/10.1007/s00253-016-7413-z . Nieuwoudt, H.H., Prior, B.A, Pretorius, I.S. & Bauer, F.F., 2002. Glycerol in South African table wines: An assessment of its relationship to wine quality. South African Journal of Enology and Viticulture 23(1), 22-30. Rantsiou, K., Englezos, V., Torchio, F., Risse, P.A., Cravero, F., Gerbi, V., Rolle, L. & Cocolin, L., 2017. Modeling of the fermentation behavior of Starmerella bacillaris. American Journal of Enology and Viticulture 68(3), 3 7 8 - 3 8 5 . h t t p s : / / d o i . o r g / 1 0 . 5 3 4 4 / ajev.2017.16108 .

SIGNIFICANCE OF THE STUDY One of the main advantages of using this sequential inoculation would be the preferred metabolism of fructose as opposed to glucose by Starmerella bacillaris. This could be used as a tool to lower fructose concentrations before initiating the fermentation by Saccharomyces cerevisiae , thereby reducing the risk of a stuck fermentation. Other than that, the potential lower alcohol production and the higher glycerol production could have additional sensory advantages. Another study did, however, report variable acetic acid and acetaldehyde production amongst strains (Rantsiou et al ., 2017) and should be considered when considering this technique. The findings in this study could contribute to diversifying wine composition, however, in many instances, the differences in concentration reported in this study is marginal and would likely not have any direct sensorial impact. The limitations of this study are that the wines were not sensorially evaluated using a trained sensory panel.

– For more information, contact Dr. Carien Coetzee at carien@basicwine.co.za.