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The French researcher Antoine Gobert has discovered that the yeast "Starmerella bacillaris" can significantly reduce the alcohol yield during the fermentation of wine. Starmerella bacillaris is a yeast that does not belong to the Saccharomyces yeasts and was already suggested for grape fermentation in conjunction with Saccharomyces cerevisiae about a year ago. Studies showed that Starmerella bacillaris could help improve wine quality due to its moderate production of volatile acid and many glycerols. Some strains had also been shown to have an antifungal effect against grey mould on grapes caused by Botrytis cinerea. In the past, non-Saccharomyces yeasts were considered undesirable because they were often isolated from wines with sluggish fermentations or negative sensory profiles.
Gobert's initial experiments showed a drop in alcohol content of 1 to 1.5 per cent. After further experiments in three-litre bioreactors with controlled circulation, oxygenation and nutrition, he even managed to achieve a reduction of 2.5 per cent. According to his own statements, he paid particular attention to ensuring that the fermentations were faultless and produced flawless wines.
The wines fermented with the Starmerella bacillaris yeast were sensory analysed by oenologists from the University of Dijon and other experts. They noted an increase in complexity and fruity notes. The company Sofralab, where Gobert is employed, will now test the new yeast on a large scale. The company will offer it to several partner wineries and is fine-tuning the production and drying method. The yeast is expected to be commercialised under the name "Starbella" before the 2023 harvest.
(al / sources: vitisphere, oeno-one.eu; photo: wikimedia, JJ Harrison)