Re: Is there live yeast cells in wine (finished product)

Hi Randy,

I had a terrible time finding information on this from any kind of scientific source. In the scientific literature, all the information about wine yeast concerns characterization of different strains, details about the fermentation process, and other things that have nothing to do with the presence of yeast in finished wine.

What I have found is that winemakers sometimes add an extra step to the winemaking process to ensure that all the yeast cells are dead. This step can be the addition of a chemical (sulfites or sorbates) or treatment with heat. A different approach to winemaking is to let the yeast ferment all the sugar, so they no longer have a food source, or have created a concentration of alcohol that is toxic. In this case, it’s not really clear when or if all the yeast are dead. Live yeast can scavenge nutrients released from the dead cells, and alcohol may prevent the yeast from growing without killing them. If live yeast are present in the “final” product, that is, the bottled product sold to the consumer, there is a risk that the flavor of the wine will change for the worse as the yeast continue their metabolic activities.

Because of the diversity of winemaking techniques, you can’t count on all wines being free of viable yeast. I would guess that the large scale operations take steps to kill any remaining yeast for the sake of producing a consistent product.

The premise of your question is interesting in specifying an allergy to live yeast. Unless you have some information to the contrary concerning a specific case, it seems quite unlikely that someone with a severe allergy to live yeast would not be allergic to dead yeast. People with food allergies have to be careful to avoid any processed foods containing the food to which they are allergic. That is, it does not matter if the food has been cooked, it presents a danger to them in any case. Any allergen present in live yeast will still be present (perhaps in reduced amounts) in yeast that has been killed by any method gentle enough to not destroy the taste of the wine.

Guidelines for people with yeast allergies suggest avoiding wine. This makes sense even if there are no viable yeast cells in the wine, since some remains of yeast cells will be present in any undistilled yeast fermented product.

Sorry I couldn’t find a more clear-cut answer for you, I hope the information above is helpful.

Alex Brands