Q: Are there any yeast-free wines? Can I drink wine if I have a yeast allergy?—Robbie, Aberystwyth, Wales
A: We have single-cell fungi called yeast to thank for the miracle of alcoholic fermentation, which turns sugar into alcohol and carbon dioxide. Without this process, beer, wine and leavened bread as we know them wouldn’t exist. And though yeast isn’t always added during the winemaking process, without yeast entering the equation somewhere along the way, it’s impossible to get from grapes to wine.
According to Ben Montpetit, vice-chair and associate professor in the Department of Viticulture and Enology at UC Davis, wine and yeast are fundamentally inseparable. “When someone says yeast, I assume [they mean] Saccharomyces cerevisiae. I am unaware of any commercial wine made without S. cerevisiae. Even in cases where someone … performs a spontaneous fermentation, S. cerevisiae is [almost always] present at the end of the fermentation.” He explains that the ubiquitous yeast almost inevitably gets into the fermentation “via the grapes, materials, equipment used or just from the general environment.”
Montpetit continues: “If we define wine as an alcoholic drink made from fermented grape juice, it would be possible to use organisms other than S. cerevisiae to make a dry wine.” However, using a non-Saccharomyces yeast would simply involve using another type of yeast. While non-yeast micro-organisms, including “certain species of bacteria,” could theoretically be used for alcoholic fermentation, Montpetit says “it is unlikely that the product produced by these other types of fermentations would taste anything like wine.”
For the allergy sufferers out there, Montpetit recommends avoiding wine entirely. “Whole yeast may be present in the wine, depending on the processing [and] filtering performed before bottling. The wine will certainly contain individual yeast components (e.g., proteins and many metabolites beyond ethanol).” And since it’s impossible to know which yeast components a person is allergic to, or how many of those components end up in a given wine, “avoidance would be best.” As always, talk to your doctor about incorporating wine into a healthy lifestyle.—Kenny Martin