Post on 12-Jan-2016
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DESCRIPTIONPropagação de Fermento
WRANGLING WILD YEAST AND OTHER MICROORGANISMS, OFF THE GRID
BY ALESZU BAJAK
A yeast grows in Brooklyn. Several strains of wild yeast, actually. At home in his DIY laboratory in Sheepshead Bay in south Brooklyn, Dmitri Serjanov isolates yeasts from bottles of Belgian beers like Cantillon and Saison Dupont. After drink-ing the beer down to the dregs, he pours the yeast out, grows a colony on petridishes and inoculates a small amount of low-specific-gravity wort. He then offers his stock-piled yeast to brewers on the internetSerjanovs online handle is BKYeastin exchange for other beers and yeasts, or for $10 to cover shipping. Tucked into a corner of his small apartment, Serjanovs lab consists of a bookcase
lined with beakers, test tubes and erlenmeyer flasks, and a desk that holds a microscope connected to his computer. He installed a mini-hood and encased the area with fiberglass to keep it sterile. The squat refrigerator nearby is actually an incubator kept at 86 Fahrenheit, optimal growing conditions for yeast. He also has a narrow workspace for pipetting, stirring and mixing, and spreading yeast colonies on petridishes. When his work is done and its lights out, an eerie ultraviolet light stays on, keeping his shelf sterile.Though his day job is as a molecular biologist at a local medical school, Serjanov is a self-
proclaimed yeast rancher. And the yeast hes wrangling in his laboratorywhich is undeniably better outfitted than those at most microbreweriesreflects a larger trend. In their quest to push the boundaries of brewing and redefine craft beer styles, American brewers are deep into experimenting with brewings most fickle ingredient: wild yeast.Prized for the nuances the yeast imparts on beerwhich include earthiness, spiciness and that
inscrutable barnyard characterBrettanomyces is the most popular of the wild yeast once only seen in Belgian Lambic beers that were fermented by throwing open the brewery doors rather than throwing in a yeast slurry. And as demand for Brett and other wild strains skyrockets, geeks like Serjanov are stepping up to meet it.
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GO BRETT OR GO HOMELeading the Brett charge are artisanal American breweries like Crooked Stave in Colorado, Maines Allagash and Oxbow breweries, Anchorage Brewing in Alaska, and Californias Russian River and The Bruery. Theyve developed innovative recipes, added specialty ingredients like hibiscus and rye, and inoculated with strains of Brettanomyces. Using Lactobacillus and Pediococcus bacteria that give off lactic acid, a souring agent, theyve also riffed on European sour styles, like tart, light-bodied Berliner Weisses and sour, malty Flanders Browns.Once I started experimenting with
Brettanomyces, I fell in love with it, says Gabe Fletcher, owner and head brewer of Anchorage Brewing Company in Alaska. He uses Brett in almost every beer he makes, and most of those sit around aging in barrels for six months to a year. Its really an amazing yeast once you embrace what it can do and give it its time. Fletcher praises Bretts ability to scavenge for
oxygen in his hoppy beers, a characteristic that keeps beers like Galaxy and Bitter Monk fresh after a year or more. While Fletcher sources from yeast banks in the
lower 48, and from his growing culture of bacteria and wild yeast donated by Russian River, some pro brewers are reaching out to hobbyists like Serjanov. Sometimes they just hear about it and want to
give it a try, sometimes they have tasted homebrew made with it and liked it well enough to want to do it themselves, Serjanov says. As far as I know, there are commercial batches already bubbling away in some places with yeast I isolated from Cantillon bottles. As many professional brewers know, homebrewers
offer a wealth of hair-brained ideas that wouldnt be worth researching or developing at a commercial brewery. Which is why if youre looking for people isolating and brewing with wild yeasts and bacteria, you neednt look any further than the homebrewing community.
Top left: The Bruerys
Bottom left: Oxbows
Tim Adams filling barrels.
Above right: Many of the
beers aging in Anchorage
Brewings barrels have
been inoculated with
YEAST TRAPSWhen Jeff Mello goes on vacation, his packing list always includes an agar plate, sterile cotton swabs and a test tube; the mason jars of unfermented wort that he uses at home dont travel so well. He leaves the yeast traps outside to collect anything floating around the garden. Like a wines terroir, Mello wants to find strains that are specific to a certain place. He recently dubbed a species of yeast he found and isolated from his own backyard Saccharomyces arlingtonesis, after his hometown, Arlington, Va. Mello calls his open-source yeast project Bootleg Biology, and though he has
no formal science training, hes learned to make his own petridishes and identify ale yeast colonies by sight, and hes tweaking a growing medium that will only host Brettanomyces (adding lactose to the agar has produced mixed results, but hes got more promising agar media in the works). Crooked Stave and Russian River are putting out beautiful beers that are in high
demand, says Mello, who recently left the nonprofit world to work on Bootleg Biology and in a craft beer shop. Why not harvest your own funky strain? Homebrewing first piqued Mellos interest in the hobby; then he read Yeast,
Jamil Zainasheff and Chris Whites tome on the subject. He says the section on building your own yeast lab is probably aimed at scientists with large-scale aspi-rationsand while commercial yeast labs are great, Mello says, I also wanted to do something a little more holistic. So in addition to isolating local yeast, the goal of Bootleg Biology is also to create the most diverse library of brewing microbes and cultures possible. That means all cultures are sourced and isolated exclusively from bootleg sources like the air, kombucha, yogurt, honey, fruit and whatever else we can get our hands on. Some are isolated, but many remain as a blend or mix of cultures that can be brewed with directly.Eventually, Mello will sell and trade his cultures online, but for now, hes hand-
ing out samples to adventurous souls at events and homebrew club meetings. In return, he asks that brewers send him their fermentation metrics. The goal for the near future is to build a solid database that aggregates that data, with analytics for each strain displayed on bootlegbiology.com. That kind of precision and documentation is important, says Ben Woodward.
Woodward is isolating his own cultures in Saxapahaw, a small town smack dab in the center of North Carolina. He and his wife, Dawnya, are months away from open-ing up Haw River Farmhouse Ales, a 10-barrel brewery that will feature local yeast. Last February, Woodward set out a few yeast traps covered in cheesecloth
around town. After harvesting three samples that smelled promising and won-dering how he was going to brew with them, he was approached while he was pouring at a beer festival. Deborah Springer, a postdoctoral associate at Duke University Department of
Molecular Genetics & Microbiology, had read our blog post and offered to help clean up our samples, isolate the yeast cells and run DNA sequencing on them to help organize our efforts, says Woodward. The bug turned out to be a strain of Pichia fermentans yeast, which shows up about a year into Belgian Lambic fermentations. Woodward hopes to use it commercially as the primary yeast for his year-round Belgian Blonde.
Jeff Mello captures
yeast samples from
Yeast is one of the last unexplored ways of brewers giving their own spin on recipes, he says, citing Mystic Brewery (in Massachusetts), Jester King (Texas), Jolly Pumpkin (Michigan) and Odell (Colorado) as examples.Woodward is about to start working with the vine-
yard across the Haw River to isolate a strain of Brett from its grapes to use in the secondary fermentation of an upcoming brew. That way, we could ferment with a truly Saxapahaw Brett, Woodward says.
HISTORY REPEATINGCharlotesville, Va., brewer Hunter Smith thinks of Brett in its historical context. With the rise in popularity of Brett, the owner of Champion Brewing thinks its funny that brewers and winemakers used to be so pre-occupied with eliminating it from their barrels. In fact, hes watched as his father and the staff have worked tirelessly to stave off Brett infections at his parents vineyard in the nearby Blue Ridge Mountains. Now, he purposefully inoculates their old barrels. Ive got a beer going in the barrel now, points
out Smith. Its a 9-percent American Pale Sour being aged in Afton Mountain Chardonnay barrels with Brettanomyces, Lactobacillus and Pediococcus. One winemakers Brett barrel is another brewers treasure.The breweries of old most likely had barrels rife
with souring bacteria or Brettanomyces-esque bugs, whether by design or not. In fact, people who have plumbed historical accounts of 19th-century Porterswhich were aged in wooden barrelshave found mentions of sour, tart and astringent, which leads them to believe that the barrels Porters were once-upon-a-time aged in were also home to bacteria and wild yeast.While some attempts at homegrown yeast might
end up in the compost bin, Fletcher of Anchorage Brewing says that the successes are worth the trouble. I have done wild fermentation before with great
results. Ive also had not so good results, he says. But thats the chance you take when dealing with wild yeasts. Thats why they are called wildyou dont always know what the result will be, but you wont know unless you try.
There are a lot of characteristics that are very specific to Brett, says Neva Parker, head of laboratory operations at White Labs, a leading retailer of brewing yeasts in San Diego, Calif. Parker has spent a lot of time raising Brett, and identifying whether samples sent in by brewers are yeast or bacteria.
Brett are very high acid producers for a wild yeast, so we grow them on a [medium] that has an alkaline buffer, explains Parker.
Her plates have calcium carbonate embedded in them; she offers up Tums as a ubiquitous substitute. If they are Brett or a Brett-like species, they will produce a lot of acid clearing. In other words, when the Brett colonies grown on top of a cloudy, gelatin-like agar, a smooth, clear halo will form around the colonies, becauseif you remember your Chemistry 101an acid (the Brett metabolism) and a base (the cal-cium carbonate) neutralize each other.
Parker stresses that harvesting wild organisms can be risky for novices. If fermen-tation doesnt happen, then the beverage isnt safe to drink, because you could be capturing something that is potentially pathogenic, she says. Ethanol and low pH are key to keeping out the bad bugs.
She suggests that DIY yeast ranchers should have a strong background in microbi-ology and yeast culturing; start by getting familiar with culturing and maintaining brewers yeast, then apply these techniques and foundation to culturing other organ-isms, she says.
If the yeast sample does ferment, then youre not going to die, she laughs. With fermentation, the pH drops, and you get alcohol made. The organisms that are going to survive that are not going to hurt you. But stillbe careful out there.
Aleszu Bajak is a former lab rat turned
science writer currently into
Rye IPAs. Follow @aleszubajak on