If you use wild yeasts to vinify your wines, why do you do it, and what advantages does this approach offer? And if you strictly use commercial yeasts, why do you prefer this approach?
Bob Cabral, Williams Selyem (Russian River Valley, California). You’ll be quite surprised (ha!) that I have an opinion on both methods of fermenting grapes. The first part I will speak to is using single inoculums of cultured yeast. At Williams Selyem, since 1985 we have been using a single yeast isolate now kept viable commercially and referred to as the “Williams Selyem yeast.” Its origin is the old Jackass Hill zinfandel vineyard owned by the Martinelli family and it was isolated by local microbiologist Marty Bannister from a lot of zinfandel wine that Burt Williams had made in 1984.
The spirit behind our winemaking procedures here at Williams Selyem is to remove as many variables within the process and be a bit on the more “light-handed” side of crafting pinot noir. This approach, which includes the use of one barrel cooper and barrel type (François Frères), one yeast strain (WS isolate), one malolactic strain (ML-34), the use of 15% to 25% whole clusters, and generally replicating the fermentations is an attempt to show the true expressions of those individual sites or blocks within a site. A cultured yeast can help provide some consistency to our house style, so that whoever is making the wines, they will best represent Williams Selyem as a brand, with any luck to extend the longevity of the business. There is a certain amount of predictability to rate of fermentation, aromas produced during fermentation, mouthfeel or texture to the wines, color extraction and stability, tannin extraction, etc. The processes we attempt to follow are not particularly difficult to perform, but execution in the proper sequence and in a timely manner can sometimes be a bit of a challenge.
I have also been crafting a wine here at Williams Selyem since 2008 from a unique three-acre block on our estate vineyard near the new winery. Within this block, I planted every 18th vine to a different clone, replicating it throughout the entire three acres, all on one rootstock (420A), making it nearly impossible to ever consider harvesting the clones separately. A true field blend of pinot noir genetic material, or, as I call it, “Block 10-Mass Selection.” I am attempting to implement as many organic viticultural practices as I can to be as “light-handed” in the field as I am in the cellar. In my twisted mind I am attempting to articulate an actual terroir within a specific site on our estate vineyard.
I am using slightly more whole clusters (approximately 35%) for more rachis or stem tannin, I am not inoculating with the WS yeast isolate (although it is definitely finishing the fermentation when I look at juice under the microscope) to let the normal flora of yeast within the site come through in the finished wine, and I do not inoculate with the bacteria isolate ML-34 for malolactic fermentation (same thought as with primary fermentation). I have been using a bit less new oak (40% to 50% instead of 60% to 80%), but aging it four or five months longer (approximately 21 months). I do see some slight differences in the overall effect to the finished wines from the past four vintages. I personally enjoy and appreciate these differences and have now planted in 2011 another 2.5 acres (of 25 clones of pinot noir on 101-14) on a hillside at our Drake Estate Vineyard in Guerneville. The spirit is to replicate a similar philosophy at another site. Because my first couple of attempts do not have much age to them, I’m not exactly sure what the long-term aging effects of these practices will be. Only time will tell.
Rupert Symington, Symington Family Estates (Douro Valley, Portugal). In the case of Port we see little advantage in using cultured yeasts, as their main purpose would be to avoid a stuck fermentation, which in the case of Port is never an issue. My cousin Charles, our head winemaker, feels that the other main benefits of cultured yeasts are only generally felt toward the end of the fermentation, and therefore are not applicable to Port. So we’re perfectly happy using wild yeasts for all grades and styles of Port.
As regards our dry Douro reds, with the high natural sugar levels of our Douro grapes, using wild yeasts there can be a real risk of a stuck fermentation unless there is a significant bleed of juice prior to maceration [used to concentrate the juice that remains], something that can prove extremely expensive and that is only really viable for top-end wines. So on the whole, unlike with Port, we use cultured yeast strains for most of our dry Douro reds, which in our opinion certainly do not seem to suffer in terms of quality from the different treatment and display all the characteristics of true vins de terroir.
Louis Barruol, Château de Saint Cosme (Gigondas, France). I only use wild yeasts because they make better, more complex wines. Wines of diversity. It goes along with an organic estate: it’s kind of “logical.” The wines have more character as the commercial yeasts tend to make them look alike.
Larry McKenna, Escarpment Vineyards (Martinborough, New Zealand). Escarpment does utilize indigenous yeasts in the majority of its ferments. All pinot noir, chardonnay, pinot blanc and barrel-fermented pinot gris is wild-fermented. We believe we obtain more even, slower fermentations that don’t peak as quickly or as actively. The resulting wines, particularly in the case of pinot noir, seem to be rounder and richer on the palate than inoculated ferments. The wines show greater complexity depending on the year. It’s usual to expect slightly elevated volatile acidity and sulfides and lower alcohols. There is less biomass in the ferments, a lot less lees, I guess due to the slower fermentations. If you follow the instructions for yeast additions a far greater yeast population is added at the start of fermentation, resulting in very rapid ferments and far too may yeast cells being produced.
Part of the approach is trying to produce wines that are a truer reflection of their site. If the active yeasts are coming in from the vineyard then it’s a fair assumption that they will have site-specific characteristics that all become part of the terroir and then ultimately impact on the wine in a unique site-specific way. One more step towards “natural wines,” if you like.
We do use commercial yeasts on riesling and tank-fermented pinot gris. In this case we are looking for purer fruit flavors and a greater fruit expression. In other words, less fermentation-derived complexity. These wines are far more delicate and transparent so they must be handled more carefully. They are tank-fermented and require more temperature control of the fermentation process.
Reinhard Löwenstein, Weingut Heymann-Löwenstein (Mosel, Germany). Do we use them? I think we let them use the sugar of our grapes. Why? Well, who says that the soil is more important than the microbes of the vineyard? We know nearly nothing about all those yeasts and bacteria running around in our vineyards. What we do is: we see the rocks, we see the soil. Who will write the book about the differences of the microbes? As far as we are looking for an individual expression of terroir, there is no doubt that there is a absolute need to let the fermentations run spontaneously. Each barrel has to start and end fermentation by itself with its own microbes.
And, very interesting: the University of Mainz made a microbiological screen in two of our barrels from the moment of pressing until the summer of the following year, when we first added some sulfur. They didn’t find any saccharomyces cerevisiae.
Anthony Hamilton Russell, Hamilton Russell Vineyards (Hermanus, South Africa). We do use wild yeast, but in a slightly different way. In 1993, with the assistance of some researchers we collected yeasts directly from the bunches in the vineyards. We found eight different yeasts, five of which were “good yeasts” and three of which were “spoilage yeasts.” Most of the five good yeasts were new and had not been found elsewhere. We conducted trial ferments with each of these five to pick the best, which is now responsible for a significant percentage of our chardonnay and pinot noir ferments. We call this “endemic yeast” Hamilton Russell Vineyards yeast 5. We keep a culture of it and use it to inoculate our chosen batches.
In our opinion, this particular yeast adds a lot to the character of our wines. It is a slow and poor converter of alcohol, produces more glycerol, and does not over-dramatize the fruit.
A lot of so-called wild yeast ferments are simply ferments largely completed by a dominant commercial yeast present in the cellar. We do on occasion ferment a component or two without any inoculation, but this can be risky in some years, particularly in our chardonnay, given the difficulty of monitoring every barrel closely. However, we do like the idea of a kind of yeast relay, with several yeasts each dominating different stages of the ferment, with the strongest (usually a commercial yeast) finishing the job. Each yeast contributes something.
We generally use a mix of yeasts, choosing one for each of our different vineyards depending on the ripeness and character of the grapes when they come in—both our own and our preferred commercial yeasts for certain desired characteristics. We use up to five yeasts for our chardonnays and four for our pinot noirs.