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Feral Yeast Wines at Efeste Winery

2009 March 11
by Eric Hwang

Wild Yeasts

We know that wine is made by fermenting grape juice with yeast. But up until the last century, wine was made using spontaneous fermentation and relied on the indigenous wild yeasts that occur naturally on grapes. Yeast was only added within the last century to ensure consistent results. That’s because not only are wild yeasts found on the grapes, but other less desirable microorganisms also make their home on the grapes and equipment. These other microorganisms can produce off-odors, such as rotten-egg smell, or undesirable results, such as vinegar. On the plus side, if monitored diligently, spontaneous fermentation can result in wine with very complex flavors. Since the fermentation takes longer to start, skins stay in the grape must longer resulting in wine with more body, color and richer depth of character. Certainly something most winemakers desire in their wine. However, because it’s very difficult without lab analysis to determine what is in the must, relying on wild yeasts to multiple to sufficient numbers to ferment, while hoping that other undesirables don’t ruin the must is a very risky proposition. That’s where cultured yeasts help.

Cultured Yeast

Cultured yeasts were developed to help ensure consistent results. The species of yeast most used today in winemaking is Saccharomyces cerevisiae. The most desirable characteristic of S. cerevisiae is its ability to convert sugar into alcohol and continue this fermentation process until alcohol levels are upwards of 13%, sometimes even as high as 18%. Some strains of S. cerevisiae can produce wine with fruity aromas and good mouth texture, others can ferment in low temperatures or high acids. The varietal of grape also dictates which strain of yeast is used. There are as many different strains of yeast available to the winemaker as there are specific results desired.

When a winemaker inoculates the must with a cultured yeast, chances are that it is a strain of S. cerevisiae. At most wineries, when the grapes are crushed, a solution of sulfur dioxide is added to the must to kill or retard the growth of wild yeasts and other bad bugs. After which, the cultured yeast is added in sufficient number to start the fermentation quickly, become the dominate strain and prevent other yeast from multiplying enough to have an effect, good or bad, on the wine. The result is consistently reliable results. Something most large wineries are striving for. 

Feral Yeast

Feral yeast occupies the gray area between wild yeast and cultured yeast. Depending on where you look, you’ll find a different definition of feral yeast. In talking to winemakers and others in the industry, I believe it is a combination of wild and cultured yeast that invariably dominates a terroir or even a winery after yeast is present on just about everything, from soil and vines to the barrels and the equipment to the hands and clothing of the people who work with the wine daily.  Many wineries in Burgundy still use spontaneous fermentation and it is believed that it works well because the entire region has developed so much of the dominant strain of good yeast through incorporating spent skins and lees back into the vineyards. This is believed to contribute to the specific terroir of this region as well.


Feral yeast is getting a lot of attention these days because of the desire to go “green” and offer an organic wine free of sulfur dioxide. But beyond the organic and additive-free kick, many winemakers are relying on feral yeasts to produce more complex and elegant wines with greater body and character than their cultured yeast counterparts. One such winemaker is Brennon Leighton of Efeste Winery in Woodinville, WA.

Final Final

Barrel Tastings at Efeste

After tasting the latest releases at Efeste, and purchasing the 2006 Ceidleigh and 2005 Final Final, shown in photos, I was lucky enough to have a barrel tasting of future releases with the winemaker including the 2008 Syrah Red Mountain (presumably for the Ceidleigh), 2008 Mouvèdre/Syrah, 2008 Syrah from Dick Boushey’s vineyard (probably to be used in the Jolie Bouche) and the 2007 Big Papa (not this upcoming 2006 release but next year’s release).  As good as this year’s releases are, these upcoming releases are all Brennon’s doing, made using feral yeasts and are tasting great already. You see, Brennon became the winemaker at Efeste a couple of years ago and didn’t get to influence every aspect of the wine until the 2008 harvest when he decided to use feral yeast fermentation for all the wines. I can’t wait to taste the final products when they release in a couple of years.

Me: “These are all feral yeast?”
Brennon: “Yeah, all of them.”
Me: “Wow, that’s pretty bold.”
Brennon: “Bold? I like that. Much nicer than how I’ve been described…”

The final barrel tastings were a couple of 2007 Syrahs, same grapes, same kind of barrels, everything the same except for the yeast. One inocuated with cultured yeast the other used just the naturally-occurring feral yeast. The difference was surprisingly obvious. The commercial yeast offered up a big and bold wine in a very typical California New-world style. The feral yeast was richer, more refined and elegant with a distinctly Old-world style. The result of a winemaker’s skill and careful attention. If you haven’t had wine made with indigenous yeasts, then you’re in for a treat when these wines finally release.  The down side: we have to wait for more than another year for this fine nectar.

Many thanks to Brennon and Efeste Winery for taking the time and allowing me to sample his wine.

Copyright © 2009, Eric Hwang and BricksOfWine. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Hwang and BricksOfWine with appropriate and specific direction to the original content.

One Response leave one →
  1. Nick Bryce & Kerry Beinke permalink
    May 25, 2009


    Here we will make a claim to fame by association and that is that the mentioned Ceidleigh is our daughter, the full bodied one; and what a buzz this is! In fact, Ceidleigh is working in America, at one of the summer camps in Maine after wintering at Big White in BC.

    Cheers to our small world.

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