The SOMM Journal

June / July 2017

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Page 22 of 124

22 { THE SOMM JOURNAL } JUNE/JULY 2017 { getting geeky } IN THE CURRENT STATE OF not only the wine business but the food industry in gen- eral, much of the populace gravitates toward terms such as "natural" and "organic." The past few decades of mass production have inspired a movement back to homemade and small production. As the pendulum swings, though, sometimes the bigger picture gets lost. Is native yeast fermentation innately a better choice, or is inoculating with commercial yeast not as taboo as the reputation it has garnered? Let's start with the general truths of fermentation yeasts. Ambient yeasts are floating around in the atmosphere, and fermentation will start spontaneously if the grape must lies in warm enough conditions. Yeast genera such as Candida, Kloeckera, Metschnikowia, Pichia and Brettanomyces can all be present in the unfermented juice, and yeast, as do all living organisms, operate on the survival-of-the-fittest model. As the fermentation temperature increases and nutrients deplete, Saccharomyces cerevisiae will inevitably dominate, the other yeast strains dying once the must reaches approximately six percent alcohol by volume. So, is it better to allow the native yeast to begin the fermentation in the interest of developing various aromas, or is it preferable to immediately introduce a commercial strain of Saccharomyces cerevisiae in order to fully control the fermentation? Recent panels at Somm Journal events have included several winemakers among whom inter - esting dialogue developed, with vintners advocating very different philosophies of and approaches to their choice of yeast. This piqued my interest. In large production, inoculation with Saccharomyces cerevisiae is a no-brainer—there's too much at risk to relinquish control of something so vital. In small production, I was always under the impression that natural yeast automatically yields a higher-quality prod - uct, but I am now reconsidering that concept. While it is surely true that the ambient yeast generate unique aromas, different strains of Saccharomyces cerevisiae also elicit distinct aromas when matched with various clones of grape varieties. Researching and deliberately choosing the resulting aromas delivers a high-quality product too. Another interesting thought introduced was the idea that native yeast fermentation may not really be all that native. Unless the facility in which a wine is fermented is brand new, without any previous ferments, the natural selection concept of yeast suggests that Saccharomyces cerevisiae likely subverts any other yeast in the facility, meaning that native fermentation may even be instigated by Saccharomyces cerevisiae itself. One last consideration involves the idea of terroir. Many believers in native yeast fermentation stem from a minimalist approach to winemaking in general, a view I gener - ally support, so when the idea was introduced that native yeast fermentation may hinder terroir expression, I was again intrigued. The argument suggested that allowing several different yeasts to begin the fermentation, while encouraging complex aromatics, also grants that expression to the yeast rather than to the grape and site. Does inoculating with one yeast strain, then, allow the overall terroir to emerge in the wine instead? Ultimately, all that I have resolved is that yeast presents yet another choice in winemaking, another tool in the toolbox, just like choosing an oak barrel treatment or whether to fine or filter. Whether electing to rely on natural yeast or actively selecting yeast to initiate fermenta - tion, the choice aligns with a winemaker's overall philosophy, and no choice can be wrong. PHOTO: FOTOLESNIK VIA THINKSTOCK Exploring the Virtues of Yeast by Allyson Gorsuch Ultimately, yeast simply presents yet another choice in winemaking.

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