Brewing with Brettanomyces (plus some Brett clones)

Upon seeing the title to this article, you might say, “Whoa, I’m not into lambic.” However, while Brettanomyces strains are important to the production of lambics, Brett can and is used in the production of other beers, including classic styles and modern creations.

The wooden tanks at Rodenbach are maintained to let in a small amount of
oxygen over time. The wood harbors Brettanomyces, one of many organisms
that contributes to the character of this sour beer.

Brettanomyces is yeast; just not our good friend Saccharomyces cerevisiae (i.e., brewer’s yeast). Brettanomyces may also be called Dekkera. Dekkera is the name for the spore-forming version while Brettanomyces is used to refer to the non-spore forming version. There are many different species of Brett and in some cases, one species may be referred to by different names in different sources.

Beer or wine fermented in unlined wooden vessels are very likely to be tainted by Brettanomyces since Brett can survive for extended periods in the wood. There is evidence that at least some strains of Brett can slowly eat the sugars in the wood that other organisms can’t process.

In the very early part of the 20th Century, Brettanomyces was first isolated from wood-aged British strong stock ales by N. Claussen at the Carlsberg Brewery in Denmark. The name Brettanomyces means “British brewing industry fungus.” (The name Saccharomyces means “sugar fungus.”)

Porter and Brettanomyces

In the glory days of English porter (in the 18th and 19th Centuries), brewers built immense unlined wooden vats for aging their beers. Beers would age for up to a year before blending with younger beers for serving. These aged beers became somewhat sour and were called “stale,” a desirable characteristic. The stale porter could be worth two to three times as much as the young beer and aging porter became a capital-intensive business to satisfy the need for large volumes of stale porter needed for blending. Brewers held large dinner parties on the floor of new vats to commission these immense structures. Some of these vessels were as large as 20,000 barrels. The building of larger and larger vats continued through 1814 when a porter vat burst at the Horse Shoe Brewery in London. The ensuing deluge destroyed the brewery and the neighboring housing, resulting in the death of eight people.

It is very likely that Brettanomyces played a major role in the souring (staling) of historical porters though there were undoubtedly other organisms present as well.

Classic Brett Styles

Historically, Berliner weisse is said to have had Brettanomyces notes though the dominant souring agent is Lactobacillus. In the traditional process, the wort wasn’t boiled so other organisms may have had the opportunity to contaminate the wort.

In Belgium, the traditional farmhouse style saison was likely to have had a Brett character and even today the lambic family of beers depends on Brett (and many other organisms) for its character. (See my article “Lambic Brewing,” in the October 2004 issue of BYO for more information.)

Likewise, since the Belgian Flanders red (as typified by Rodenbach Red) is still aged in unlined oak, it has contributions from Brett along with other organisms.

And of course, the world classic Trappist ale Orval — from Brasserie de l’Abbaye Notre-Dame d’Orval SA — incorporates Brett in its profile. (See the May/June 2005 issue of BYO for an Orval clone.)

Modern Brett Beers

Two well-known, California-based craft brewers who have done some pioneering work on beers influenced by Brettanomyces are Tomme Arthur of Pizza Port Solana Beach and Vinnie Cilurzo of Russian River Brewing.

Pizza Port Solana Beach produces a number of unusual beers including the Brett-influenced beer Cuveé de Tommé. Cuveé de Tommé is a fairly big beer, coming in around 11% alcohol though modeled after the Flanders Red style. The beer is aged in wood and at least the first few barrels were bottle conditioned and marked to show which barrel the beer came from.

Pizza Port’s Mo’ Betta Bretta was collaboratively produced with Peter Bouckaert of New Belgium Brewing Company and was fermented with only Brettanomyces (i.e. no brewer’s yeast). The very effervescent, fairly dry beer has a complex aroma including notes of pineapple and other tropical fruits.

Russian River Brewing Company produces the beers Supplication, Depuration and Temptation. These are all the result of a mixed fermentation with brewer’s yeast and Brettanomyces and are aged for a year in wine barrels made from French oak. Russian River’s Sanctification is fermented with two strains of Brettanomyces as the only yeast. A little Lactobacillus (lactic acid bacteria) is added to provide added acidity to this dry and spritzy beer.

New Belgium Brewing Company’s La Folie is in the style of a Flemish Red Ale (what we might call a Flanders Red). La Folie (the folly) is aged in wood barrels for one to three years before bottling.

To my palate, the Sour Brown Ale produced by New Glarus Brewing also has a Brett characteristic with a sour pie cherry note reminiscent of some strains of B. bruxellensis. According to the brewery’s webpage the beer has a long lager in their oak casks.  Kansas City’s Boulevard Brewery has experimented with Brett-influenced beers, but haven’t released any.

Brett Basics

Brettanomyces is a souring agent and will produce both lactic and acetic acids. It will normally only produce a relatively low level of acetic acid and even then only under aerobic (with oxygen) conditions. Extended aging in wood allows a slow penetration of oxygen, resulting in some acetic acid in the beer. The Rodenbach Brewery has to periodically disassemble their large oak aging vats to scrape the inside of the wood staves to maintain the proper oxygen penetration rate in order to get their desired level of sourness.

Side effects of a Brettanomyces fermentation are often characterized by a sweaty horse, horse blanket, leathery, or even wet horse aroma that some people might generalize as barnyard-like aromas. Additional characteristics sometimes produced by Brett include spicy, smoky, medicinal, and even cheesy. In some strains there can be a somewhat unpleasant mousy (or mouse-urine like) aroma.

Brettanomyces-influenced fermentation will usually show a pellicle, a coarse off-white mat that floats on the surface. The pellicle tends to protect the beer from oxidation as well as protecting the beer from molds and Acetobacter (acetic acid bacteria). A pellicle can even form in a bottle if there is enough food left for the Brett to feed on.

Some strains of Brett will produce distinct cherry pie-like flavors and aromas. For example, the B. lambicus strain Wyeast sells is known for producing the cherry characteristics.

Brettanomyces is a super attenuating yeast — it is able to process sugars and dextrins that normal yeast can’t process. Over time, Brett will consume almost all the sugars and dextrins in a beer. Most beers with any traces of Brett will end up very dry as the yeast can survive for months or even years in the fermenter or bottle.

Brett is capable of producing CO2 and therefore can be used to bottle condition beers. However, the continued action of Brett almost always leads to increasing levels of carbonation over time. If a Brett-influenced beer is bottled too soon, you run the risk of making “bottle bombs.”

Brettanomyces produces three compounds with high sensory profiles: 4-ethyl phenol, 4-ethyl guaiacol and isovaleric acid. 4-ethyl phenol can be detected by most people at 200–600 parts per million. 4-ethyl phenol gets credit for “band-aid” and barnyard aromas and 4-ethyl guaiacol for the wet, burnt wood, spicy smells. Isovaleric acid and its esters can be downright fruity (it’s a component in commercially-prepared blueberry, pineapple and peach aroma enhancers), but can also contribute a rancid character.

Brettanomyces has nutritional requirements similar to brewer’s yeast, though some sources indicate that certain strains can’t tolerate alcohol levels above 13%. Brett doesn’t grow well at cool temperatures or at pH values lower than about 3.4. (Most beers have less alcohol and higher pH levels than this, however.)

Brett is a slow growing organism and grows best in a temperature range between 13–30 ºC (55–86 ºF). At the higher end of the growth range, Brett is likely to produce more unpleasant flavors and aromas whereas at the low end it seems the characteristic flavors and aromas are emphasized.

Our brewing knowledge of Brett strains is in its infancy and the whole area is ripe for homebrewers that want to experiment. We can, however, learn from those brewers who have used Brett before.

Brewing with Brett

There are essentially two ways Brettanomyces can be used — as a secondary component of a mixed fermentation or as the dominant (or sole) microorganism in a fermentation. Using Brett along with other organisms — as in brewing lambics, Flanders red ales or Brett-tainted historical styles — is fairly straightforward compared with brewing Brett-dominated beers (including 100% Brettanomyces fermented beers).

Brett-influenced Beers

To increase the Brettanomyces-derived characteristics in a beer, you should pitch a small amount since it appears many of the characteristic compounds are produced during the growth phase. Pitching one container of commercial Brett in a mixed fermentation, or even inoculating a beer in secondary with another Brett-influenced beer is sufficient.

Brett characteristics may take a while (as long as few months) to appear, but will increase steadily over time given the right conditions. If you condition your Brett-influenced beers at ale temperatures or higher, the “funk” will increase with time and may reach acceptable levels in as little as six months, though many Brett-influenced beers must be aged longer than this. Using a plastic bucket, which allows a very small amount of oxygen to reach the beer over time, may accelerate the Brett activity.

In bottle-conditioned beers, Brett will continue growing slowly, increasing the Brett character, but also potentially developing dangerous levels of carbonation if the beer was bottled too young. When bottling Brett-influenced beers, use less priming sugar than you normally would and bottle the beer in the thickest bottles you have.

There seems to be some synergy between Brett and Pediococcus (a lactic acid bacteria found in lambics) that allow the apparent attenuation to approach 100% (yielding an FG near 1.000.)

Brett-dominated Beers

To use Brettanomyces for the primary fermentation strain, you need to grow a large cell count with a starter. My Brett starters use the same wort as my regular starters — a gravity of 1.020 to 1.030, lightly hopped, with a small addition of yeast nutrients. The proper pitching rates are not well defined for Brett when compared to Saccharomyces, but Tomme Arthur and Vinnie Cilurzo agree that you should pitch as much yeast as you would in a lager, if not more. For 5-gallon (19 L) batches, a one gallon (~4 L) starter should provide enough yeast. Keep in mind, though, that Brett grows slower than Saccharomyces in wort, so you will need to give your starter more time to ferment.

Likewise, the proper oxygen level for Brett-dominated beers is less well understood. Both Mo’ Betta Bretta and Sanctification are produced with aeration rates typical of ales of their respective original gravities. Both Tomme and Vinnie use Servomyces® (a yeast nutrient sold by White Labs) in their 100% Brett beers, but they also use it in their normal beers as well. A little yeast nutrient can provide an “insurance policy” for any beer.

Fermentations with Brett may not be as ordered as those with Saccharomyces. Vinnie reports that Sanctification exhibited a normal lag time — “we pitched at night and it was fermenting when we arrived at the brewery the next morning” — and 75% of the fermentation was done in 5 days. It took another two weeks for the beer to drop to SG 1.008. In contrast, Tomme Arthur reports getting a “lager-like” fermentation, with the gravity dropping about a half degree Plato (about 2 “gravity points”) per day. His fermentation lasted 3 weeks. Some of this difference may stem from the differences in fermentation temperatures — Vinnie started Sanctification at 72 °F (22 °C) and let it rise to around 80 °F (27 °C) as the fermentation peaked. Tomme kept Mo’ Betta Bretta fermenting in the 64–75 °F (18–24 °C) range. Chris White (of White Labs) cautions that some Brett fermentations “just don’t work,” especially if an inadequate amount of yeast is used. As Vinnie puts it, “Brett has a mind of its own.”

Both of the California Brett beers showed higher degrees of attenuation than achieved by normal ale strains, although the beer’s final gravity did not drop as low as is typical for lambics. Brett strains are not very flocculent and you shouldn’t expect your Brett-dominated beers to fall crystal clear.

Sources of Brett

As homebrewers we can easily obtain at least five different strains of Brettanomyces. White Labs sells cultures they call B. bruxellensis, B. lambicus and B. claussenii, while Wyeast sells cultures they call B. bruxellensis and B. lambicus. The characteristics of these yeasts will vary depending on whether you pitch a small amount into a mixed fermentation or grow up a large starter for a mostly or entirely Brett-driven fermentation.

White Labs says their claussenii strain produces a pineapple-like aroma and shows a “low intensity” of Brett character, with their bruxellensis and lambicus showing progressively more Brett character. In a mixed fermentation, their lambicus strain produces the typical lambic “funk.”

Wyeast says their bruxellensis strain produces the classic sweaty horsehair character when used in a lambic fermentation. Their lambicus strain has a “pie cherry-like” note.

Keeping it Clean

To prevent cross-contamination, pay close attention to cleaning and sanitation when using Brettanomyces in your brewery. You may want to dedicate any tubing and soft equipment that contacts Brett to your “wild beers,” but there’s no need to fear Brett if you use some common sense.


Mo’ Betta Bretta clone
(5 gallons/19 L, all-grain)
OG = 1.060  FG = 1.011
IBU = 12  SRM = 7  ABV = 6.3%

9 lbs. 12.5 oz (4.44 kg) 2-row
pale malt
15.7 oz. (0.44 kg) CaraPils malt
15.7 oz. (0.44 kg) flaked oats
17.2 oz (0.49 kg) Munich malt (10 °L)
3.2 AAU Magnum hops (60 mins)
(0.2 oz/5.7 g of 16% alpha acids)
1 capsule Servomyces (yeast nutrient)
Brettanomyces anomalus cultured
from bottle or White Labs WLP645
(B. claussenii) yeast
(4 qt./4 L starter)
0.66 cups corn sugar (for priming)

Step by Step

Make a 2 qt. (~2 L) yeast starter in a gallon (3.8 L) jug and let ferment. Add another 2 qt. (~2 L) of wort to starter when done. Aerate at each step. Mash at 150 °F (67 °C) for 60 minutes in
4 gallons (15 L) of water. Collect about 6.5 gallons (25 L) of wort and boil for about 2 hours, yielding about 4.5 gallons (17 L) of wort. Add hops for final 60 minutes of boil. Add yeast nutrients for final 15 minutes of boil. Cool wort and transfer to fermenter. Aerate wort and pitch yeast sediment plus half the liquid in the yeast starter to yield 5 gallons (19 L). Ferment beer at 64–75 °F (18–24 °C). Let beer condition for at least 4 weeks before bottling.

Extract option:

Replace all the grains in the all-grain recipe with with 0.5 lbs.
(0.23 kg) of 2-row pale malt, 0.5 lbs.
(0.23 kg) of CaraPils malt, 0.5 lbs.
(0.23 kg) of flaked oats and 0.5 lbs.
(0.23 kg) Munich malt. Steep the  crushed grains — a total of 2.0 lbs. (0.91 kg) — at 150 °F (66 °C) in 3 qts. (~3 L) of water. Add 2 gallons (7.6 L) of water to “grain tea” and boil with 2.33 lbs. (1.1 kg) of light dried malt extract. (You can heat the 2 gallons (7.6 L) of water separately while grains steep.) Boil wort for 60 minutes, adding the hops at the beginning of boil. Add 4.5 lbs. (2.0 kg) of light liquid malt extract and yeast nutrients with 15 minutes left in the boil. Cool wort and transfer to fermenter. Aerate beer and top up to 4.5 gallons (17 L) with water. Follow remaining all-grain instuctions.

Thanks to Tomme Arthur of Pizza Port for the recipe for Mo’ Betta Bretta.

Sanctification clone
(5 gallon/19 L, all-grain)
OG = 1.056  FG = 1.007
IBU = 31  SRM = 6  ABV = 6.3%

9 lbs. 14 oz. (4.5 kg) 2-row pale malt
(or Pilsner malt)
13.3 oz. (0.38 kg) Vienna malt
1 lb. 3 oz. (0.54 kg) Weyermann
acidulated malt
6.7 AAU Sterling hops (FWH)
(1.3 oz./36 g of 5.3% alpha acids)
1.5 AAU Sterling hops (90 mins)
(0.28 oz./8.0 g of 5.3% alpha acids)
2.8 AAU Sterling hops (0 mins)
1 capsule Servomyces (yeast nutrient)
Brettanomyces bruxellensis culture,
Wyeast 3112 (B. bruxellensis) or
White Labs WLP650
(B. bruxellensis) yeast
(3 qt./~3 L starter)
Brettanomyces lambicus culture,
Wyeast 3526 (B. lambicus) or
White Labs WLP653 (B. lambicus)
yeast (1 qt./~1 L) starter)
Lactobacillus delbrueckii culture or
Wyeast 4335 (L. delbrueckii)
bacteria (3 oz./100 mL starter)
0.66 cups corn sugar (for priming)
ale yeast (for bottle conditioning)

Step by Step

Mash for 60 minutes at 152 °F (67 °C) in 3.75 gallons (14 L) of water. Collect about 6 gallons (23 L) of wort, add 0.5 gallons (~2 L) of water and boil  down to 4.5 gallons (17 L), which should take about 2 hours. Pitch “bottom half” of yeast starters. Ferment starting at 72 °F (22 °C), but let temperature rise as high as 80 °F (27 °C) during fermentation, which takes 3–4 weeks at Russian River. Bottle with ale strain for bottle conditioning.

Extract option:

Replace grains with 1 lb. 3.0 oz. (0.54 kg) 2-row pale malt and 13.3 oz. (0.38 kg) Vienna malt. Steep the crushed grains at 150 °F (66 °C) in 3 qts. (~3 L) of water. Add 2 gallons (7.6 L) of water to “grain tea” and boil with 2 lbs. 2 oz. (0.96 kg) of light dried malt extract. Add 4.25 lbs. (1.9 kg) of light liquid malt extract and yeast nutrients with 15 minutes left in boil. Cool wort and top up 4.5 gallons (17 L) with water. For the the remaining steps, follow the all-grain instructions.

Thanks to Vinnie Cilurzo of Russian River Brewing Company for the information used to compile this clone.

Issue: October 2005