Funk Vs. Acid: What DOES “Sour” Really mean?
What makes a beer sour? In purely scientific terms, “sourness” is a function of acidity—the more perceptible acidity in a beer (as measured by ph, or more accurately as measured by titratable acidity), the more one would say it is “sour.” However, in popular perception, funkiness—that typically Brettanomyces-derived trait commonly referred to as “barnyard” or “horse blanket” or “wet hay”—is often confused or mislabeled as sourness, when in fact the two are very different.
That funkiness is primarily a product of Brettanomyces yeast, while acidity in beer is primarily a function of lactic-acid bacteria. This is why beer styles such as Berliner Weisse can be sour (acidic), but still very clean—most brewers use pure Lactobacillus to produce acidity but do not involve Brettanomyces in those beers (there are some exceptions to this with brewers who use a mixed culture including Brett to produce beers labeled Berliner Weisse, but they are the exception rather than the rule). By the same token, beers made with Brettanomyces are not necessarily sour (acidic), because Brett typically produces very little, if any, additional acid.
So why, then, do many saisons and farmhouse ales fermented with Brett taste more sour? First, Brett is a scavenger and will eat just about anything—any residual sugar left in a beer, certain yeast esters, you name it. Because sweetness acts as a buffer to reduce your perception of acidity, the reduction in that sweetness has a side effect of making the acidity already in the beer more noticeable.
The second reason is that many are not fermented with 100 percent Brett, but rather are fermented using a mixed culture that also includes Lactobacillus and Pediococcus—both of which do produce acids. spices. Our beers have pleasant tartness and cheesy-funky notes that express but then finish clean.”
House Blends
A house yeast blend is a thing of beauty among craft brewers, many of whom have gone to great lengths to create these microbial mixtures. At Jester King Brewery in Austin, Texas, the house yeast blend developed out of what Co-owner and Brewer Ron Extract calls “miniature coolship experiments.”
“We left a pan of wort to cool overnight and sent it off to a lab to isolate those yeasts. From there, we decided which yeasts to use, and [we] sourced various strains from commercial yeast labs. Over time, we created a unique blend. At this point, it is truly a house yeast— the blend of microorganisms is truly unique. When you have a mixture, it mutates and changes and becomes even more unique.”
Another blend that started out of thin air was created by Two Roads Brewing Co. in Stratford, Connecticut, when Brewmaster Phil Markowski and his team captured and
“There’s just not a lot of standard practice in the industry—every brewery has its own approach to the process and the flavor.”