Yeast in Wine
This section contains notes from our due diligence on this topic.
For another complicated wine subject we turn to Andrew Fisher of Astor Wines & Spirits for clarification.
The use of ambient yeasts allows wines to express the terroir (terrain) of where the grapes were harvested. While using yeasts in wine creates more interesting wine flavors, it is unpredictable. Due to its unpredictability, sulfites are often added to grapes to prevent the naturally occurring bacteria from acting before the ambient yeasts activate. This is the precise reason why Mr. Fisher is adamant about the presence of sulfites with the best practices for natural, organic and biodynamic winemaking.
There are also synthetic yeasts that Mr. Fisher compares to flavor additives to food. They are more predictable as to when they activate the fermentation however some have odors and flavors that change the wine.