As alcohol levels in wine seem to rise with almost every vintage, Sofralab, a French company, is launching a major test of a new commercial yeast called Starbella that could reduce the final strength of a red, white or rosé by 1-2%.
As Vitisphere reports, the secret behind the yeast that has been developed by a researcher called Antoine Gobert is that it is Starmerella bacillaris rather than the customary Saccharomyces cerevisiae. Gobert selected and isolated the specific strain in 2016 while completing his PhD at Dijon University under the supervision of Hervé Alexandre, and with funding from Sofralab.
Apart from the producing dry wines with less alcohol Starmerella has the additional potential advantage over Saccharomyces of making them texturally richer. This is because of the way it transforms fructose into glycerol. Gobert told Vitisphere that "It's in the mouth that you can feel the difference in alcohol. There is less dryness and a 'burning' sensation. The wines are fresher and more balanced. Starbella also gives them more volume and, because of its glycerol production, more fat.”
However, Starmerella is not a perfect silver bullet. Winemakers used to feeding Saccharomyces with nitrogen in the form of DAP Diammonium Phosphate - will, Gobert says, need to also add a mixture of amino acids, ergosterols and vitamins in order to compete fermentation. He also recommends the addition of up to 5 g/hl of SO2.
Thus far, experimental fermentations have involved small volumes of must and, until it is tested on commercial quantities this year, Gobert cannot say precisely how effective Starmerella will be in reducing alcohol. He acknowledges that it will be impossible to replicate the 2.5% reduction he achieved in the laboratory and notes that, the higher the initial potential ABV, the more effective his new yeast will be. At 13.5% the ‘saving’ may only be 1%, but this would still be of interest to winemakers, especially if the UK government goes ahead with its plans to tax wines according to their alcoholic strength.
Natural wine fans will, of course, hate everything about wines produced using commercial yeasts, amino acids, ergosterols, vitamins and SO2. Others, however, may welcome what sensory panels have described as more fruit and complexity – coupled with a richer texture and less alcohol.
If all goes well with the 2022 large scale tests, Starmerella will be launched in time for the European 2023 harvest.