100% Brettanomyces Fermentation

100% Brett fermentations typically create a fruit forward beer that is less funky than if the Brettanomyces is pitched into a beer that has first been fermented with Saccharomyces (see Funky Mixed Fermentations).

General Information

The method of fermenting wort with only Brettanomyces was pioneered by Tomme Arthur from Pizza Port/Lost Abbey, and Peter Bouckaert from New Belgium in 2004 with their 100% Brettanomyces fermentented Mo' Bretta, and Vinnie Cilurzo of Russian River with Sanctification later that same year . This method was further popularized by Chad Yakobson's Brettanomyces Dissertation on the Brettanomyces Project blog, and by his brewery, Crooked Stave Artisan Beer Project. While primary fermentation with Brettanomyces is a complex subject due to the wide range of characteristics of different species and strains of Brettanomyces, in general beer that is fermented with Brett in primary usually produces a surprisingly clean, lightly fruity beer (see Chapter 8 in American Sour Beers by Michael Tonsmeire for a full description of 100% Brettanomyces fermented beers). For this reason, wort that is characteristic of American IPA has been found to create wonderful beers when primarily fermented with Brett.

Typical characteristics of Brett primary fermentations (these are generalizations, and may not be true for every strain):

• Initially subdued "horsey", "funky", "barnyardy" flavors due to the lack of Saccharomyces esters/phenols (see the Brettanomyces Metabolism page for more information). However, this is a generalization and some brewers have reported getting some "funkier" flavors out of some strains.
• Light fruit characteristics.
• A longer lasting hop aroma and flavor due to Brett's ability to constantly metabolize micro-oxygenation.
• A lack of glycerol, which is a compound that Saccharomyces produces which gives beer it's slick mouthfeel. Malts such as oats or flaked wheat are often used to make up for the lack of glycerol.
• Slightly longer primary fermentation in general (3-6 weeks), although some people have reported faster fermentations between 1-3 weeks for some strains and conditions (lower starting gravity beers, for example) .
• Perceived bitterness may be quite a bit lower than the same wort fermented with a clean ale yeast.

Brewing Techniques

Obtaining a clean culture

Please note that many of the Brettanomyces cultures sold are contaminated with Saccharomyces - in particular those sold by White Labs. Brettanomyces ferments slow and a fermentation would take considerably longer to ferment out compared to a fermentation containing Saccaromyces. Besides Brettanomyces has a somewhat limited metabolism and the apparent attenuation would be quite a bit lower compared to what a comparable Saccaromyces fermentation would showcase.

Starter Information

When relying on a Brettanomyces culture for primary fermentation, a starter will often be necessary due to the fact that most yeast labs provide a small cell count for their Brettanomyces cultures. See the Brettanomyces Starter Information section for more information on Brett starters.

Wort Production

American IPA or American Pale Ale recipes are a tried and true general approach to making wort that is favorable to 100% Brett fermentations. Fruitier hops such as citra, amarillo, galaxy, etc. tend to compliment the light fruity characteristics of a Brett primary fermentation. The addition of body-increasing malts such as oats, unmalted barley, rye, wheat, or carapils may assist with the lack of glycerol that is typical for Brett , but isn't always necessary. Otherwise, wort production can remain the same as it is for an American IPA/Pale Ale recipe. Aeration of the wort before fermentation starts should be done. This will greatly increase cell growth (see the Brettanomyces Propagation Experiment). As far as we know, acetic acid is a byproduct of ethanol production by Brettanomyces and not the prior lag phase, so as long as ethanol is not already being produced then acetic acid production is not a concern . Examples of commercial 100% Brettanomyces beers that receive the same amount of initial aeration that would be typical of ales of their respective gravities are "Sanctification" from Russian River and "Mo’ Betta Bretta" from Lost Abbey .

Finishing Gravity

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Fermentation Characteristics of Individual Species and Strains

Not all species of Brettanomyces are effective at efficiently attenuating wort on their own. Additionally, some strains and species may produce better results flavor-wise than others.

• Some microbiologists have witnessed thatB. claussenii is very slow to ferment wort by itself. If fermentation finishes in two weeks, this might be due to contamination of another yeast .
• Not all strains can ferment maltose, which is almost 50% of the sugar composition of wort. These strains should be avoided for 100% Brettanomyes fermentations. See Brettanomyces carbohydrate metabolism for more details.

Questioning Conventional Wisdom

About Trois

Up until April 9, 2015, "WLP644 Brettanomyces bruxellensis Trois" was thought to be a Brettanomyces species. Following the analysis of the genetics of Trois by Lance Shaner and several other members of MTF that showed this strain to be S. cerevisiae, White Labs released a statement saying that DNA analysis showed that Trois was actually a Saccharomcyes species . Beer fermentations with the this strain (now labeled as "WLP644 - Saccharomyces brux-­like Trois") are no longer considered to be 100% Brettanomyces fermentations.

When using WLP644, it is recommended to make a 1 liter starter for 36-48 hours due to the extremely small cell count of the vials .

Are 100% Brett Beers Really Cleaner?

A lot of the conventional wisdom listed above regarding 100% Brettanomyces fermentations is anecdotal information in relation to Trois fermentations. As explained above, Trois is not actually Brettanomyces, and so conventional wisdom regarding 100% Brettanomyces beers has been brought into question. One particular area of question is the conventional wisdom that Brettanomyces requires phenols from POF+ Saccharomyces strains in order to convert 4-vinyl phenols into 4-ethyl phenols.

There is surprisingly little data to back this idea up outside of the anecdotal information gathered from brewers fermenting with 100% Trois, which was once thought to be Brettanomyces . One controlled experiment by Lance Shaner of Omega Yeast Labs and Richard Preiss of Escarpment Labs showed that the levels of 4-ethyl guaiacol and 4-ethyl phenol produced by Brettanomyces did not depend on the amount of their 4-vinyl precursors, suggesting that Brettanomyces is capable of producing 4EP and 4EG de novo (without being dependent on precursors produced by Saccharomyces). In addition to this, the possibility that some yeast labs have Saccharomyces contamination issues in their Brettanomyces products complicates the issue. This is only one data point, however, and more data needs to be researched.

A study conducted by Caroline Tyrawa measured, amongst other things, the 4-Ethyl phenol in 100% Brettanomyces Bruxellensis. It shows clear levels of 4-Ethyl phenol in wort fermented by various strains of the before-mentioned yeast. A somewhat speculative conclusion of this might be that the high ester levels of 100% Brettanomyces fermented beers might mask the funk (4-Ethyl phenol) produced. As esters tend to be chemically unstable (ref?) the fruity character of a Brettanomyces beer will fade over time allowing the funk a more prominent role.

See Also

Additional Articles on MTF Wiki

• Brettanomyces
• Brettanomyces Propagation Experiment
• Brettanomyces secondary fermentation experiment

External Resources

• Funk In the House, by Andrew J. Kazanovicz on Homebrewtalk. Sensory analysis of 100% Brett fermentations of many of the commercially available strains.
• What is Brett IPA Supposed to Taste Like. Bear Flavored Blog. Derek Dellinger. - A great general description of what 100% Brett IPA tastes like.