Beer is made by yeast, full stop. Given its pivotal role brewers are generally pretty picky about what type of yeast they let into their fermentation tanks. Scientists have classified over 1500 different species of yeast, but the vast majority of beers are made by just two species—Saccharomyces cerevisiae (ale yeast) and Saccharomyces pastorianus (lager yeast). Despite the Saccharomyces hegemony, a yeast that belongs to the genus Brettanomyces plays an important role in small subset of beers. As a distant third place, at least in terms of quantity, you can think of it as the John Kasich of brewing yeast.
Brettanomyces, or Brett for short, was first isolated from English Stock Ales in 1904 by N. Hjelte Claussen at the Carlsberg Brewery in Denmark. Despite its name (the Latin name literally means “British fungus”) the impact of Brett on the beer world is not limited to English ales. Brett plays an important role in producing the complex flavors of Belgian styles like Lambics, Flander’s Reds and Oud Bruins, as well as German Berliner Weisse. There are six known species within the genus Brettanomyces, but only two are commonly used in brewing—Brettanomyces bruxellensis, sometimes called lambicus because of its use in the brewing of Lambics, and Brettanomyces claussenii named after it’s discover Claussen, which is also referred to as Brettanomyces anomalous.
A couple of weeks ago I wrote a post about a beer many consider the quintessential Brett beer, the Trappist Ale Orval. Unlike its Belgian cousins, the Lambics and sour beers of Flanders, bacteria are not used in the making of Orval. The absence of sharp, acidic notes allows the Brett flavors and aroma come through more distinctively in my opinion. Nonetheless, Orval relies on a saison-like strain of Saccharomyces to carry out the primary fermentation. The Brett is not added until the ale yeast has had five days to ferment out most of the easily digestible sugars. Most of its work occurs after bottling, and then only slowly. The resulting taste of an Orval is a mélange of these two yeast’s handiwork, with the Brett characteristics becoming more dominant with time (see my post to read about the changes in flavor that occur as an Orval ages).
In English Stock Ales and Belgian Lambics, Brett is introduced somewhat surreptitiously through long periods of aging in oak barrels. It’s left to clean up the diacetyl produced by pediococcus bacteria and dry out the beer by slowly digesting the longer chain sugars that saccharomyces cannot eat. That doesn’t mean to imply that given the chance Brett would turn its nose up at the simple sugars present in fresh wort, it’s just that until this century no one thought to make a beer using only Brett. The first commercial example of 100% Brett fermented beer did not appear until 2004 when the Lost Abbey and New Belgium collaborated on a beer called Mo’ Betta Bretta. This was closely followed by Russian River’s Sanctification, which also contains lactobacillus bacteria as a souring agent. You can read more about the history of 100% Brett beers in Michael Tonsmeire’s book American Sour Beers.
There is ample evidence that the byproducts of Brett fermentation depend upon what it eats, which means that a 100% Brett fermented beer will take on different flavors and aromas than a conventional mixed fermentation beer like Orval. One of the leading advocates for all things Brett is Chad Yakobson, who wrote a master’s dissertation entitled “Pure culture fermentation of Brettanomyces yeast species and their use in the brewing industry” while studying in Edinburgh. Quoting from the introduction of Yakobson’s dissertation here is what he has to say about the flavors and aromas that Brett produces when it follows or competes with Saccharomyces in the fermentation process:
“Many organoleptic descriptors are used to describe the often-pungent aromas of Brettanomyces spp. Those include clove, spicy, horsey, barnyard, smokey, medical, band-aide, metallic, cracker biscuit, goat-like, apple, floral, tropical fruit and citrus.”
I’m not sure I know what a goat smells like, but that’s not necessarily a negative. Yakobson then goes onto describe how the situation changes when Brett shoulders the entire fermentation burden (i.e. pure culture Brett fermentation), the topic that motivated his dissertation:
“Most recently, delicate fruit descriptors have become sought after aromas having anecdotally been reported from wort fermentations using pure cultures of Brettanomyces spp. It is not known which strains create the pineapple-like ester characteristics, although it has become the goal of a handful of brewers to recreate techniques that have resulted in these light fruit attributes. A handful of theories exist for the possible source of the unique aromas with no study previously concentrating on a wide variety of secondary metabolites produced by Brettanomyces yeasts. It is well understood that raw materials exhibit a great influence over the behavior of yeasts and for that reason this study concentrates on the overall performance of these yeasts in association with malt based wort used in brewing. The aim of this study was to increase the knowledge of the Brettanomyces genus through providing information regarding fermentation performance and metabolite production during anaerobic fermentation.”
As some of you will know Yakobson went on to found a brewery built around Brett, Crooked Stave Artisan Beer Project in Denver. I’ve been fortunate enough to visit Crooked Stave on a couple of occasions (read a profile I wrote last year by clicking here). I think it’s one of the most innovative breweries in the country, but my chances to visit Colorado and pick up the latest Crooked Stave offerings are pretty limited. So I was excited to learn over the Christmas holidays that Seventh Son Brewing had made an all Brett beer called Winterborn, and followed it up by an all Brett Double IPA called Feral, both fermented exclusively with Brettanomyces Clausenii. I did my best to sample them every time I visited the brewery, and head brewer Colin Vent was kind enough to sit down with me in February and talk about these beers. Unfortunately this post is woefully late getting to press and these two beers are no longer on the market, but the first appearance (to the best of my knowledge) of locally brewed all Brett beers in Central Ohio still seems like an event worth archiving.
Thirty cases of Winterborn were released in thick 375 mL glass bottles, one of which came into my possession. My tasting notes are as follows:
Appearance: The beer has a deep golden-amber color. It’s translucent, bordering on opaque, and topped with a voluminous white head. The retention and density of the head are not in the same league with an Orval though.
Smell: The nose is dominated by funky, overripe pineapple, ripened to the point where it is just starting to sour.
Taste: Simultaneously fruity and musty, with a big punch of ripe pineapple surrounded by a flavor that is hard to put my finger on but seems characteristically Brett. Until your taste buds acclimate it’s a pretty intense flavor. It’s not particularly sour, nor is there a big presence of the spicy clove-like phenols that are so prevalent in Orval. The underlying malt base is that of a sweet Belgian golden ale.
Mouthfeel: Somewhat syrupy, despite the big head it could use a bit more effervescence in the mouth.
Overall: Seventh Son has definitely captured the pineapple-forward fruitiness associated with 100% Brett fermented beers. It would be interesting to see how this beer develops after spending sometime in the cellar.
My notes on Feral, which was only available on draft, are less detailed. It has a similar overripe fruity nose but unlike Winterborn where the hop character is not easy for me to discern, here they are prevalent—citrus notes from the Citra and Cascade hops, and dank, piney notes from Simcoe. Nevertheless, for an 8.2% double IPA the bitterness and hop profile are fairly restrained. Overall its a unique, fruity, very drinkable DIPA.
Talking Brett with Colin
There was a time not so long ago when the idea of bringing Brett into your brewery was a pretty scary preposition for fear that it would contaminate the equipment and its funky flavors would start showing up in all of the beers. These days there seems to be an increased willingness to experiment with it. I wondered if special precautions were taken in the relatively comfy confines of the Seventh Son brewhouse. Another challenge of working with Brett is the potential for long fermentation times. In mixed fermentation beers Brett is a notoriously slow acting yeast, but that is due in part to the fact that the Saccharomyces ale yeast has generally gobbled up most of the easily digestible simple sugars. In Chad Yakobson’s dissertation he concludes that some strains of Brett are capable of complete fermentation in 35 days. So I was curious to find out how long it took for Winterborn and Feral to complete fermentation. Here are some highlights from my conversation with head brewer Colin Vent.
PP: What strain of Brett did you use for these beers?
CV: We used Brettanomyces Claussenii from Wyeast. From what I’ve read this species tends to give more “fruity” and less “barnyard” flavors than the Bruxellensis/Lambicus species, when used in a pure culture fermentation like this.
PP: Did you take any special precautions to avoid contaminating the brewery with Brett?
CV: We took all the fittings and gaskets off the tank (there are a lot that don’t get removed every time) and swapped them out. Other than that we just made sure we did a thorough sanitizer CIP run. Every day we work to protect our beers from ambient wild yeast, other than the concentration there’s no real change between a Brett pitch and all those nasties floating around on the dust. We’ve been successful so far, so there wasn’t a huge level of concern.
PP: Tell me about the fermentation conditions. How long did it take to ferment these beers?
CV: Winterborn took a full three months to ferment, but I feel that is largely due to issues with fermentation temperature. The notes on fermenting with Brettanomyces Claussenii are pretty vague, calling for a fermentation temperature ranging from 65-80 °C. Erring on the side of caution we opted to start the fermentation at a temperature close to 65 °F, where it turned out to be pretty sluggish. For Feral we upped the fermentation temperature to 75-80 °F, which cut the fermentation time down to 20 days.
PP: Were there any surprises at the way the beers turned out?
CV: Given the quantity of hops used in the recipes, I feel the perceived hoppiness and bitterness of both beers are less that they would be if I followed a similar recipe for a sacchromyces fermented ale. Something about the Brett tends to mask the contribution of the hops. The reasons for this are not clear to me.
PP: Any other tidbits of information you’d like to share with brewers out there?
CV: Brett fermentation produces twice as much CO2 as a comparable Saccharomyces fermentation. It’s important to take that into account when packaging your beer (translation – make sure to use thick glass bottles).
PP: As I understand it we’ll have to wait until next winter for either Winterborn or Feral to reappear. Can we expect any other Brett beers in the interim?
CV: There are not any other all Brett beers on the drawing board but I’m planning to use Brett in combination with Saccharomyces in some of the saisons that will be appearing over the spring and summer months. We’ve got the first of this year’s farmhouse beers in tank almost ready for the dryhop, it’s a 3.4% table beer that incorporates the Brett c. with the Sacc strains we normally use. I’m looking to have that beer available the first week of May. (Note: This comment dates to April 13, 2016 not to the original interview on Feb 15).
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