Winemaker Bradley Brown of Big Basin Vineyards
As a viticulturalist and a winemaker, I have to count yeast among my best friends. I’m not among those winemakers afraid to let the naturally occurring, (wild/native/indigenous), yeast be our primary means to ferment our grapes. I know think wild yeast fermentations are just that – wild and uncontrolled, but I think they are missing out on one of nature’s real gifts from the vineyard. Naturally occurring, or “wild” yeast produce extraordinary results that cannot be obtained when they are killed off and replaced by cultured yeast. The secret to obtaining these results is impeccable fruit quality from well-managed vineyards and small fermentation lots (<2 tons).
At Big Basin Vineyards, all of our Pinots are fermented on their native yeast. Some claim that it is the yeast resident in the winery that are responsible for the fermentation and not the native or wild yeasts from the vineyard. Since we occasionally inoculate a fermentation at the very end when the potential alcohol is relatively high (this does not happen with Pinot, but is not unusual with Syrah), we have been able to observe that the character of the fermentation changes completely just after inoculation, i.e., the commercial yeast we were using to inoculate was not present in the fermentation prior to that point. It helps that we are fanatical in our cleanliness in the winery, so we are eliminating any undesirable yeast that might join the fermentation party uninvited. Even if somehow the uninvited commercial yeast ended up joining the fermentation prior to inoculation, I believe that the yeast that come in on the grapes are primarily responsible for at least the first half of the fermentation. And I also believe that it is exactly the diverse population of yeast present early in the fermentation that is responsible for the magic effects of wild yeast fermentations – improved mouthfeel, increased complexity. So even if a commercially produced strain of yeast were to take over the fermentation half way through, you are not losing the benefits of the indigenous yeast that started the party.
Clearly there are vineyard practices that can promote yeast propagation, and some which might inhibit it. For example, if you compost grape must that is full of brett (brettanomyces – a spoilage yeast responsible for ‘band-aid’ or ‘horse sweat’ characterics) and then spread it in the vineyard, there is a good chance that you will get brett coming in on the grapes. Additionally, any yeast used in the winery will end up in the vineyard if you pursue these practices. However, native yeast is probably native for a reason and as long as you are not continually bombing the vineyard with chemicals that kill micro-organisms, you are going to have native yeasts living there alongside other yeasts that might get introduced. Hence, if you don’t hit the de-stemmed fruit with SO2 to kill what is there prior to fermentation, you are going to start your fermentation off with a multitude of yeasts that came in with the fruit. It is this exotic mix of yeasts that are naturally occurring in the ecosystem that produces the complexity and mouthfeel we desire. And that’s why we prefer to let Pinot run wild, as it were. There is something really heady, exciting and deeply textural about wild yeast ferments, and since we are passionate in our quest to make compelling and complex wines, we prefer to dance with nature and celebrate her wildness instead of chopping down the trees to get at the ore below the surface.
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