After the grape harvest comes into the winery in the fall and gets processed from grape clusters to must and juice, the most critical part of winemaking is next: Fermentation. This is when wine acquires the flavors and aromas that make it the wine it will be. The grapes, the winery and even the people coming in to do the work, have yeast they have acquired and which is present at all times, since yeast is everywhere. This is what we call "wild", "native" or "indigenous" yeast. Fermentation depends on yeast; a small, one cell creature that lives to digest sugar and create carbon dioxide, alcohol, as well as the esters that become aroma and flavors. Those little guys find what they need in the grape juice to create wine -- oh, what a great and magical world we live in!
Many years ago, winemakers began purchasing yeast that had been derived from known good wines and grown under controlled conditions. By isolating and commercializing these yeast strains, the commercial yeast companies gave winemakers a tool for consistency that could help ensure their wine had good aromas and flavors and which was proven to withstand the rigors of temperature and alcohol, among other things, to bring the wine to a successful conclusion. So why buck the system and try using native yeast to do the fermentation job? Today, to varying degrees, makers of premium wines have been experimenting using native yeast to complete some or all of the fermentation process. The assumption here is that the risks of a stuck fermentation and off flavors and odors are worth the potential of an exceptional wine with a literal sense of place in the flavor and aroma, also known as "terroir".
Last year, we began allowing the native yeasts to spend some time alone in the juice and must to begin the fermentation, and we pitched commercial yeasts early on to ensure a successful completion of the fermentation. The commercial yeast, being universally more robust, effectively takes over at some point, but the extra flavor and aroma of the native yeast remains. This is a relatively safe way to get the best of both worlds. In the 2018 vintage we ran a bench trial of Pinot Noir on 100% native yeast to see what happened in fermentation and to test the resulting wine for flavor and aroma. It was interesting to see the fermentation period get drawn out from 10 days to about a month. My expectations included the possibility of a flawed wine, but I was pleasantly surprised by how balanced the the trial wine smells and tastes. It's still early to tell, but as the wine ages, we'll get a better idea of what we can expect in the final wine and whether we should move to run a complete barrel of wine through the process. I'll give an update in a few months.