Brewing with Brettanomyces (Brett)


By Jack Horzempa

Brewing with Brett

The two types of yeast most associated with brewing beer is Saccharomyces Cerevisiae (ale yeast species) and Saccharomyces Pastorianus (lager yeast species) but there is another type of yeast sometimes used in brewing beer: Brettanomyces (which is often referred to in its shortened form of Brett).

What is Brett yeast?

It wasn’t until the studies of Louis Pasteur in the mid-1800’s that it was known that it was microorganisms (e.g., yeast) which were responsible for the fermentation of beer. It would be a number of decades until N. Hjelte Claussen would discover another genus of yeast that is present in fermented beer.  Claussen called this new yeast Brettanomyces (which is Greek for British yeast). He published a paper in 1904 documenting his findings.

His paper discusses the importance of Brettanomyces for secondary fermentation and for producing the flavors of English stock (keeping) beers. It turns out that Brettanomyces would take residence in the oak barrels which were used to store/transport British beers, further fermenting the beer.  British brewed IPAs (circa 1800) that were sent to India ended up with lower final gravity values because of this fermentation by Brettanomyces that occurred in the wooden barrels during the long storage and transport of these beers.

In contemporary brewing Brettanomyces is often associated with Belgian Lambic brewing and also the Wild Ales of craft brewing. But beer can be produced solely with Brettanomyces in the primary fermenter and these single strain beers tend to be clean in flavor unlike the Lambic/Wild Ales where Brettanomyces is used as a secondary yeast where funky (e.g., barnyard) flavors are often produced via the secondary fermentation process.

Strains of Brett used in brewing beer today

There are a number of Brett strains available from yeast vendors and below is a short description of some of those strains.

Brettanomyces bruxellensis (Brett Brux)

For wine makers Brett Brux is considered a contaminant and is a common spoiler of red wine. The fact that Brett Brux is a hardy yeast which can colonize harsh environments not often occupied by other types of yeast makes is troublesome for the wine industry.

Bruxellensis is a nod to the area of the Senne Valley near Brussels. In French the term bruxellois means from Brussels.

In fermenting beer, Brett Brux is associated with beer styles such as Lambic, Flanders red ales, Gueuze, Kriek, and Orval, and is part of spontaneous fermentation of these beers. The important thing to keep in mind is that for these beers Brett Brux is a part of a mix of other types of yeast (and often times bacteria as well). Historically Brett Brux would have been considered a wild yeast but since this yeast can be purchased from yeast vendors (e.g., Wyeast, White Labs, Omega,…) perhaps it is time to consider this yeast as being domesticated. Brett Brux in a mixed fermentation is associated with flavors that are considered funky; flavors often described with terms like barnyard, wet horse blanket, leather,…

When Brett Brux is the sole yeast for fermentation, the resulting beer is more likely to just have flavors described as fruity but there is the potential with extended aging some of the funky flavors can develop.

Brettanomyces claussenii

Below is how White Labs describes this yeast:

“Originally isolated from strong English stock beer in the early 20th century, this yeast has low-intensity Brettanomyces character and is closely related to Brettanomyces anomalus. This strain produces fruity, pineapple-like aroma with an earthy hay-like background aroma and aroma note.”

And Omega Yeast:

“The mildest on the Brett funkiness spectrum, Brett Claussenii presents more of a leathery earthiness and some pineapple—both characteristics that are contributed in large part by the aroma alone. It does its best work as a secondary yeast.”

This yeast appears to be the best choice if only a little bit of funk is desired.

Brettanomyces lambicus

As can be discerned from “lambicus” this yeast is related to Lambic beers.

From White Labs:

“This yeast produces a high intensity of the traditional Brettanomyces characters in beer, such as horsey, smoky and spicy flavors. As the name suggests, this strain is found most often in lambic style beers but is also commonly found in Flanders and sour brown ales.”

This yeast would be the best choice if you are seeking the most intense level of funk in your beer.

Brettanomyces anomalous

From White Labs:

“Typical barnyard funk character with some fruitiness. Acidity is medium. Primary fermentation can be done with this strain, but a starter may be necessary.”

This yeast reads like it might produce an interesting beer with a combination of funk and fruity.

How to use Brett in fermenting beer

A 100% Brett fermented beer

I have personally not produced a beer solely fermented with Brett yeast but from my readings those beers tend to be less funky with fruity (esters) being the primary feature from the yeast. Perhaps with extended time in the bottle (e.g., bottle conditioned beer) some funk will express itself. In this way, with patience a single batch of beer could be the equivalent of differing beers, offering differing flavor profiles over time.

It is not always easy keeping up with developments in yeast products but I have read in the past that for some products the yeast count for Brett yeasts is less than that for brewer’s yeasts (i.e., Saccharomyces Cerevisiae, Saccharomyces Pastorianus). If this is indeed the case than a yeast starter (and perhaps even a multiple step yeast starter) will be required here.

Use for secondary fermentation

As was mentioned by Omega Yeast for Brettanomyces claussenii: “It does its best work as a secondary yeast”. Well, “best” is a subjective term with each brewer having their own thoughts on the matter. A notion that I have read is that when Brett is pitched after primary fermentation is complete, using a POF+ (Phenolic Off-Flavor positive) yeast, the Brett yeast will ‘process’ the phenols produced during the primary fermentation into funky flavors. In this context, and if funk is desired, then perhaps using Brett as a secondary yeast is beneficial. I have used the strategy of using Brett Brux as a secondary yeast in homebrewing a clone of Orval with more details later.

Use as a co-pitch with Saccharomyces Cerevisiae

In the past Wyeast provided as a Private Collection strain Wyeast 3789-PC:

“A unique blend of Belgian Saccharomyces and Brettanomyces for emulating Trappist-style beer from the Florenville region in Belgium. Phenolics, mild fruitiness and complex spicy notes develop with increased fermentation temperatures. Subdued but classic "Brett" character.”

“Trappist-style beer from the Florenville region in Belgium” is a thinly veiled reference to Orval. While there is no specific mention of the “Belgian Saccharomyces” strain, my guess is that it would be the equivalent of WLP510 (Bastogne Belgian Ale) and I am pretty certain that Brett Brux is the strain of Brettanomyces.

I have used Wyeast 3789-PC twice to brew my version of an Orval type beer. The first time I made a yeast starter but afterwards I wondered if by making a starter I might have messed up the proportions of Saccharomyces cerevisiae to Brett (maybe one yeast grows faster/more robustly than the other?).  The second time using this product I just pitched the package directly in the fermenter. These two batches were separated by a few years but it seemed to me they both resulted in very similar tasting beers. These batches of beers were very funky from the ‘get go’ with no need for bottle aging to get the funky flavors to develop. I have also aged these batches a very long time with my second batch bottled on 1/5/17; I still have a few bottles of that batch left. The flavor profile of these beers has evolved over time but I have not noticed any intensification in the level of funk in either of these two batches. What I can report is that for both of these co-pitched batches these beers held up great over many years of cellaring.

Adding Brett at bottling as part of bottle conditioning

I have no personal experience here but it would make sense that adding some Brett during bottling will permit some funk to develop over time. I am a fan of Goose Island Sofie which is a bottle conditioned Saison. Goose Island does not provide details but there is no doubt in my mind that Brett is part of this beer flavor profile with at least 6 months of bottle aging needed to perceive the funk. Does Goose Island add the Brett during the bottling process? They do not say but it would not surprise me that this is the case.

A word of caution for homebrewers deciding to add Brett at bottling: Brett will consume sugars that are present in the finished beer (i.e., sugars that the primary yeast did not process) so this needs to be considered as part of the overall priming calculation. Adding a lesser amount of priming sugar would be prudent and using extra duty bottles would be a very good idea (bottles like Orval uses for their beer).

A case study of brewing with Brett: A clone of Orval

There are now fourteen Trappist Monasteries worldwide brewing beer that have the Trappist seal

Trappist Seal

But it was not too long ago that that Trappist beers were only brewed in Belgium and The Netherlands by just seven Monasteries/Breweries: Achel, Chimay, LaTrappe/Koeningshoeven, Orval, Rochefort, Westmalle, and Westvleteren. Orval was different from those other Trappist breweries in that they only brewed one beer: Orval Trappist Ale. The beer label has an interesting logo with a fish and a ring:

Orval Beer Label

“According to legend, around 1070, Countess Matilda, from Tuscany, went to Orval, shortly after the death of her husband Godfrey the Hunchback. Sitting on the banks of the source, she dropped the wedding ring, a souvenir of her late husband. The search for the ring proved fruitless. After a prayer at a nearby church, Matilda returned to the stream. Suddenly a fish leaned out of the water, holding the countess's ring in its mouth. Delighted Matilda exclaimed: "really this place is Val d'Or" or the golden valley. Out of gratitude, she decided to found a monastery in this area.”

The other difference between Orval and the beers from the other Belgian/Dutch Trappist breweries is that Brett is used to brew this beer.

Orval Monastery

Ed of edsbeer.blogspot (see link below) traveled to Orval in 2015 and documented his tour of the brewery.


For folks who enjoy travelogues this is a very interesting read!

Ed provides a number of details about the brewing of Orval. Here are some snippets from the article:

“The grist for Orval is pale (50% proant free), cara and a small amount of black malt (one sack per 280hl!).”

I was heretofore unfamiliar with the term “pronat free” and a quick web search resulted in:

“ProAnt Free Malt is produced from proanthocyanidin-free malting barley. This type of variety was first bred in the early 1970’s and these varieties do not contain proanthocyanidins thus one of the precursors of biological haze is absent in the resultant malt, wort and beer.”

It would appear that Orval uses proanthocyanidins free malt for about half of the pale malt.

Ed then states: “Sucrose is added after cooling, raising the gravity from 1.042 to 1.054”.

The fermentables then seem to be mostly pale malt with some cara (crystal malt) and a little bit of black malt along with some sugar (sucrose).

Ed did not provide any specifics on which ale yeast strain is used for the primary fermentation but he did provide details that Brett is added at bottling: “The beer is down to 1.004 before bottling and drops to 1.000 after the Brettanomyces has done its work.”

But there is a valuable clue in that sentence that prior to bottling the final gravity is 1.004. This is a very low final gravity for a Belgian ale strain to achieve and in other articles I have read, Orval conducts a secondary fermentation with Brett and this would explain the low value of 1.004. So, it turns out Orval has a rather complex fermentation process:

  • Primary fermentation with a Belgian ale yeast strain
  • Secondary fermentation with Brett
  • And even more Brett added during bottling to further bring down the gravity as part of bottle conditioning

When it comes to hopping Ed provides a number of details:

“Hop extract is added in the copper and some hop pellets are added to the lauter tun as an antioxidant.”

“The beer is dry hopped with bags of whole Strisselspalt hops in conditioning tanks, for between 10-20 days at 15°C.”

“The wort has 50 IBU and the beer 32-35.”

Not much help there as regards which hops are used in the kettle and what amounts/schedule. He did provide a hop variety used for dry hopping but I have read a number of other sources where they state that Styrian Goldings is used for dry hopping (plus late kettle additions). Hmm?

To build up a recipe to replicate Orval is going to require some further ‘detective work’ and below is my thinking on how best to proceed:

Malt/fermentable choices

I am thinking that Pilsner Malt is likely the malt used for “pale” malt. As regards the choice for “cara” I am thinking that some Caravienne is a good choice. The addition of a small portion of Black Malt requires a good guess on how much to use and you will see below in the recipe that I choose to just use a small portion of Special B to provide the needed color for this beer (and some further malt flavor complexity). Since Ed just mentioned “sucrose” that is an easy solution for me since table sugar is sucrose.


From Ed’s article I know that hops are used both in the kettle (but which varieties?) and for dry hopping. There are a number of other sources which suggest that the kettle hops are a combination of Hallertauer Hersbrucker and Syrian Goldings and in addition they state that Styrian Goldings are utilized for dry hopping. From my experience brewing other Trappist style beers I am going to make an executive decision to use German Magnum hops for bittering and Styrian Golding hops for late kettle additions and dry hopping.

I will be targeting a bitterness of 33 IBUs to be within the range mentioned above.


As discussed above, Ed did not mention a specific yeast strain for primary fermentation but the Mr. Malty website indicates that WLP510 (Bastogne Belgian Ale) is sourced from Orval. Well, that seems to be a no-brainer.

But which version of Brett should be used? White Labs describes WLP650 on their website: “A historic brewery in Belgium uses this yeast in secondary fermentation and bottling to produce the signature flavor of its beer.” I say “bingo” here!

Original Gravity

Ed tells us what to do here: 1.054 (but I will bump this up a few points since I won’t be adding Brett during bottling).

Without further adieu:

Jack’s Orval Recipe

Batch Size: 5.5 gallons

Target OG: 1.058

Target FG: 1.005

Color: 9 SRM

Target Bitterness: 33 IBUs

Target ABV: 6.9%


  • 9 lbs. Pilsner Malt
  • 0.5 lb. Special B Malt
  • 0.5 lb. Caravienne
  • 1 lb. Table Sugar (sucrose)
  • 0.8 ounces German Magnum Hops (10% AA)
  • 3 ounces Syrian Goldings Hops (3% AA)
  • WLP510 (Belgian Bastogne Ale) – primary fermentation (make a yeast starter or pitch multiple packages)
  • WLP650 (Brett Brux) – secondary fermentation

Additional items:

  • 1 tsp. rehydrated Irish Moss flakes (last 15 minutes of boil)
  • ½ tsp. Wyeast yeast nutrient (last 10 minutes of boil)


Mash at a water-to-grist ratio of 1.5 qts./lb. Adjust brewing water if needed (e.g., lactic acid addition) to achieve a mash pH of 5.2 – 5.4. Mash at 150 °F for 60 minutes. Sparge until approximately 7 gallons of wort is achieved (tailor amount based upon your boil off rate to obtain 5.5 gallons of wort post boil).

Boil vigorously for 75 minutes in an uncovered brew kettle adding the German Magnum hops at the beginning of boil. With 15 minutes of boil remaining add the rehydrated Irish Moss flakes and with 10 minutes remaining the Wyeast yeast nutrient along with 0.75 ounces Styrian Golding hops. Add 0.75 ounces of Styrian Goldings hops for the flameout (end of boil) addition. Also add the sugar at the end of boil and stir to dissolve.

Chill wort to 68 – 70 °F and pitch yeast.

Ferment warm (e.g., 70 °F) until primary fermentation is complete.

At the completion of primary fermentation add the Brett Brux and 1.5 ounces of Brett Brux. Allow the Brett Brux to complete secondary fermentation and then package. I recommend bottling (i.e., bottle conditioning) for this beer. I choose to conduct the secondary fermentation within the primary fermenter but transfer to a secondary vessel if you prefer.


Replace the Pilsner Malt with 6 lbs. Briess CBW Pilsen Light dry malt extract.

In a separate pot steep the specialty malts (Special B and Caravienne) in 1 gallon of hot water (e.g., 150 – 170 °F) for 30 minutes.

Dissolve extract in enough hot reverse osmosis/distilled water or filtered tap water to yield a pre-boil volume of around 6.5 gal. Adjust this volume as needed to account for your boil-off rate. Stir thoroughly to dissolve the extract and bring to a boil. Add the liquid from the steeped specialty malt to the brew kettle.

Boil 60 minutes. Add the first hop addition with 60 minutes remaining in the boil. With 15 minutes of boil remaining add the rehydrated Irish Moss flakes and with 10 minutes remaining the Wyeast yeast nutrient along with 0.75 ounces Styrian Golding hops. Add 0.75 ounces of Styrian Goldings hops for the flameout (end of boil) addition. Also add the sugar at the end of boil and stir to dissolve.

Chill, pitch, and ferment as above.

This beer will evolve and last over time. I recommend that you patiently drink these beers over a period of several years.

Orval Beer Clone


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