BREWERS’ PERSPECTIVES More than One Way to Sour a Beer
Not only can sour fermentation be applied to any number of beer styles, but it’s also achieved using a variety of techniques. Here, some of the country’s most talked-about sour-beer brewers weigh in on how they do it.
SOUR BEERS ARE HOT
and fashionable right now,” says Phil Markowski, the brewmaster at Two Roads Brewing in Stratford, Connecticut. “American brewers are now leading the charge, applying sour fermentation to all sorts of styles of beer.”
All About the Base
At The Rare Barrel, an exclusive sour brewery in Berkeley, California, the beers begin as three base ales named after their colors: gold, red, and dark. “We brew the beer, wait three to six months and then taste the base beers without any additions,” says Jay Goodwin, the cofounder and director of brewing and blending. “Then we sit down with several fruits, spice tinctures, and other ingredients and evaluate the beer for strengths and weaknesses and decide what works best. Along the way, we’re trying to take copious notes to explain how we made these flavors.”
The base beers at The Rare Barrel are usually fermented with Brettanomyces yeast and Lactobacillus bacteria during primary fermentation in stainless steel. Two to four weeks thereafter, the beers are transferred into oak barrels where they age from three months to six years. All of The Rare Barrel’s beers are blended— whether from barrels within the same batch or barrels from many different batches—as the final step before serving. “Blending lets us dial in variables such as acidity and balance to produce beer that we love,” Goodwin says.
“Through all these fermentation experiments, we start to learn more and more about all these different processes; we add new tools to our tool belts. We take these shots in the dark, then look back and evaluate, and use that knowledge to proceed.”
Brett-lacto primary fermentation is one good way to make sour beer, Goodwin says, but it’s not the only way. “I’d say the most common method is Russian River Brewing Company’s,” he speculates, “in which you ferment with a brewer’s yeast and make sure there’s a lot of residual sugar post-primary fermentation, basically trying to save food for wild yeast and bacteria to eat later.”
From there, that “Russian-river method” involves adding those wild yeast and bacteria in secondary in an oak barrel and letting that beer age in the oak barrel
method—especially for a period of time. The trouble with that for homebrewers—goodwin
explains, is that wild yeast and bacteria aren’t always strong enough in that secondary step and don’t yield as complex beers. “Russian River has been growing its culture for a long time. It’s extremely strong,” he says. “So while it makes sense to emulate the people who are doing it best, brewers can’t just buy a mixed culture and expect it to be as flavorful as Russian River’s.”
Another method of souring beers that Goodwin is noticing among breweries is hot-side wort souring, also known as sour mash or kettle souring. “It’s basically introducing bacteria so you infect wort with Lactobacillus, letting the beer get as sour as you want. You follow that with a boil to kill off all the Lacto. Then you send it to the fermentor with brewer’s yeast, achieving acidity in a shorter amount of time.”
Goodwin recommends kettle souring for brewers or homebrewers without the storage space for barrels. Not only will it save room, but it will also create fewer infections in the beer.
The Solera Approach
Two Roads sours some of their beers using the solera method, in which a portion of the aged beer is drawn out of a barrel— or series of barrels—containing the sour culture, while fresh beer is added. For Two Roads, this method is an attempt to keep a complex stew of wild yeasts and bacteria in relative balance. “We’re trying to keep the culture in constant motion,” says Phil Markowski. “We keep it fed, pull off of it, run fresh beer in, and keep it going so that we get as repeatable a result as possible from batch-to-batch. These cultures are finicky and act in concert