Grape growing and winemaking is an old industry. Really old. We even know there have been wine critics since Roman times. One asset of working in such an old industry is that a lot of important decisions have already been made for us. For example, we know that Chardonnay and Cabernet Sauvignon have been and will likely always be very popular grapes to grow and make wine from. Humans are naturally very curious critters and have been selecting and breeding grape varieties since we’ve been making wine. When we see an odd grape vine that has a special characteristic, say the vine seems to be more disease resistant or makes better quality fruit, we take it and clone a million more grape vines from it. That’s the nature of discovery and progress. So, after several thousand years of concentrated selection and breeding I feel comfortable that we have grape varieties that have stood the test of time as being compatible with human tastes.
It doesn’t stop there though, humans have unknowingly selected something else critical to the winemaking process – yeast. Our best friend in the cellar is a single celled organism in the same family as fungi. Like many single celled critters they have the rather fortunate ability to generate energy without the need for oxygen. They prefer to make energy with oxygen, it’s a lot more efficient, but can make do without it. In the absence of oxygen, such as in a vat of crushed grapes, yeast generate energy from grape sugar and produce ethanol (alcohol) as a byproduct. Fortunately for winemakers they do it voraciously, in the presence of a lot of ethanol (that would otherwise kill most any other critter in the vat), and without a lot of stinky byproducts. Slam dunk. This magical critter has the scientific name Saccharomyces cerevisiae. It is unique in those respects just mentioned and for something else – it is generally not found in nature. In the vineyard, grapes have a myriad of single celled critters on their skins, many of which are yeast, but not S. cerevisiae. This critter is so specially adapted to winemaking that it is only found in wineries. It is the only yeast that can withstand the otherwise lethal amounts of alcohol in finished wine. It is the only species of yeast left over at the end of fermentation. So, after thousands of years of winemaking, something found in microscopically small numbers in nature has found a home and a future in the winery.
As a winemaker with a science background I’m always experimenting in the cellar. If something has always been done one way I want to find a different, better way to do it. Again, it’s the nature of being curious and progressive, and not relying solely on anecdotal evidence. But we all have to make educated guesses and put our efforts towards those decisions with the largest potential for improvement. Like I said before, some of these decisions have already been made for us, like what grape varieties to grow and what yeast to use in the cellar. S. cerevisiae has an insurmountable track record. Better yet, I can buy a 100% pure strain of S. cereivisae that was selected, isolated, and cultured from a famous Viognier winery in France for my own Virginia Viognier. This is better than a slam dunk, this is a half-court shot at the last second to win the game! Case closed, right? Wrong.
Enter the “artisan” winemaker. This is a person that likes to practice “traditional” methods in the cellar. They will tout their minimalist style and wear their affectation like a gaudy full length fur coat. In actuality, all fine wines are made relatively the same way, with modern techniques. Stainless steel tanks, temperature control, yeast nutrient, cultured malolactic strains, oak barrels, these are all modern conveniences in the industry that everyone uses. One of the latest fads is not adding a cultured yeast strain to must to initiate fermentation. The idea is that indigenous yeast strains riding in to the winery with the grapes will do the job, more naturally, without the modern technology of cultured yeast strains. And because the process is natural, without the intervention of the winemaker, the resulting wine is supposed to be more complex.
Early on in fermentation these wild yeasts are co-mingling and active to some extent even when a cultured strain of S. cerevisiae is added. That seems to be established in the literature. What’s also established is that these wild strains are very sensitive to alcohol, and if they are active to the greatest extent possible in a fermentation, they die off at around 5-7% alcohol. The job is finished by S. cerevisiae. Where did it come from though if it didn’t come in from the vineyard on the skins of the grape? It was always there in the winery. If you’ve ever added a cultured yeast strain, you can be sure it has taken up residence in your winery. Single celled organisms are Earth’s most successful creatures and their reproductive techniques can withstand very long periods of dormancy and very inhospitable conditions. Even if there is some fermentation performed by indigenous yeasts, the results are mixed at best. Even proponents of wild fermentation admit that you can get some stinky results. However, when the results are good, the results are really good. Could this great result be the efforts of the wild yeast? Sure. Has it ever been proved? Heck no. Is it risky? Of course. Could it simply have been this great wine, not having received cultured yeast, was fermented in whole by a resident strain of S. cerevisiae? Most likely.
So the artisan winemaker has used a cultured yeast strain on one lot of grapes in one corner of the cellar and performed a “wild” fermentation on their best lot of grapes in the other corner. Both fermentations finish to completion and the “wild” fermented wine is not surprisingly deemed the better of the two. Conclusion? It must have been the “wild” fermentation. The human mind is unfortunately plagued by this phenomenon. We like to attribute good results to conscious decisions – usually those made that include a lot of thought, effort, or money. There are a hundred decisions that we make in this business that influence the quality of the wine. And still more factors beyond our control have their input (e.g. weather). It may be wishful thinking to attribute good results to that one “brilliant” decision you made. It very well could be, but at least have some data to back it up. The methods you would have to use to prove that a wine was dominated by wild yeast are very technical, expensive procedures still relegated to university research labs. In short, they’re simply not done by wineries. It is a bold (and probably erroneous) statement to say that a wine was fermented with wild yeast.
We make wine at Rappahannock Cellars using what we consider to be minimally invasive, traditional techniques. But those are vague concepts. We do everything we think we have to and nothing that we don’t. Sometime “minimally invasive” changes the character of the wine quite drastically – like ageing wine in oak barrels. The change is, of course, for the better. I’ll suggest here that using a cultured strain of S. cerevisiae is the more traditional, less invasive technique. Using technology to extract the best of nature and leave the worst is progress. It’s still natural, just the best of natural.
-Jason
Vintner of Rappahannock Cellars
