Sour beer brewing is less challenging than you may imagine, but takes far more cleaning, sanitizing, and planning than you could ever concieve. If you are a new brewer, this probably isn't for you. If you are more experienced, well then give these articles a read. Sour brewing is rewarding, and you can make world class beer at home. Much of this information is covered in our other posts on the subject. Episode 1, Episode 2, Episode 3, Episode 4
What is Brettanomyces?
|Brettanomyces isn't just another kind of Saccharomyces. It is an entirely|
different species of yeast. Full size available ath the end of the post.
What makes it different from ale or lager yeast?
There is a lot that makes Brett different from ale and lager yeast: the genus and species for one, the potential flavor compound production, the fermentation activities and the formation of a pellicle, just to list a few. What is important to know is that it is a very different organism and does not ferment the way that brewers are accustomed to, with ale and lagers. Brett have the ability to ferment out most of the carbohydrates that traditional brewer’s yeast leave behind; some even have the ability to ferment larger carbohydrates beyond tri-saccharides, like maltotriose. Another key to understanding and using Brett is that the flavor impact is greatly influenced by the time of use and stress factors.
Are there different kinds of Brettanomyces?
There certainly are different kinds of Brett. It is a completely different genus. Some Brett have been isolated from different regions of the world and some have been isolated from different industries: beer, wine and other industries (we won’t go into this). For both beer and wine, Brett is viewed, for the most part, as an infection. Some beer styles need Brett for the beer to fit into that style category (Lambic and gueuze come to mind) and can actually improve the flavor slightly in wines (research the impact on red wine production, if you are interested). The most common strains of Brettanomyces are anomalus, bruxellensis, claussenii, custersianus, naardenensis, and nanus. Each species will present different characteristics and flavor impact on the beer (or wine) and will have a different preferential fermentation environment (think S. cerevisiae vs. S. pastorianus).
What are the flavors produced by Brett yeast?
There are many flavors that are produced by Brett, some that are the same/similar to Saccharomyces and others that are unique to the Brettanomyces genus. I have been fortunate enough to use Brett in both primary fermentation and as a secondary fermentation and the flavors produced are extremely different in each. The major sensory compounds associate with Brett fermentation, weather primary or secondary, would be 4-ethylphenol (horse blanket component mentioned earlier), 4-ethylfuaiacol (4-EG, similar to 4-VG phenolics) and isovaleric acid (smells like old, aged cheese).
Why is Brett called wild?
Brett is called “wild” because of the impact on beer that was primarily fermented with Saccharomyces and Brettanomyces ability to survive and ferment carbohydrates that are usually remaining after the Saccharomyces has finished. Again, I have to remind everyone that cerevisiae and pastorianus were once wild yeast but are now isolated and produced so they are more pure strains, however humans are doing this with Brett, so I can’t use that to explain why it is called wild.
Another reason for Brett being called wild, is due to the flavor implications. Beers that contain Brett won’t necessarily have a “horse blanket” or “aged cheese” flavor, but it is possible to detect those flavors if the Brett has been stressed. Actually, all Brett beers (meaning primary fermentation done without Saccharomyces) have a very nice, fruity character, similar but not the same as Saccharomyces beers. Of course, there is still some background notes of the “off flavors” produced by Brett, but the beers could be mistaken for Saccharomyces beers, by the untrained pallet. Getting back to the question, I think another reason for Brett being called “wild” is because they are present in the air and on the skins of fruit. Again, I have to go back to the fact that this is how humans started pure Saccharomyces cultures, but there is less commercialized Brett today (not to say that it will always be this way). Traditional lambic producers will use “coolships” (koelschips) for cultivating natural yeast and bacteria that are in the air during certain times of the year and with certain weather/environmental conditions. This allows any natural, or “wild”, yeast and bacteria to land in and grow in the cooling wort. If you ever have the chance to see one (there are a few in the US), it really is a sight to see!
Does temperature of fermentation impact Brett fermentation like it does ales and lagers?
Yes, temperature definitely affects the Brett. It is always important to know that any microorganism that is used in beer, wine, or any other “fermentation” such as bread making or cheese making will be susceptible to the environmental conditions such as temperature. Generally, Brett will have similar reactions to temperature as our friends, Saccharomyces.
So will Brett perform well at lower temperatures?
Brett will ferment at lower temperatures. Just how low… that is dependent on the species and strain (again, think ales and lagers). Depending on the species and strain, Brett will produce a cleaner flavored beer at lower temperatures, generally speaking.
So it will ferment, but it won’t put off some of the same flavors?
Exactly! Many flavors produced are environmentally influenced. An easy way to understand this is by comparing to ale or lager yeast (I seem to be saying this a lot, but for those who haven’t made Brett beers, it is an easy comparison to understand). If you are making an ale and you split the wort into two fermenters and ferment one at room temperature and ferment the other in a car, in direct sunlight in the South (like here in TX, in the summer), the resulting beer will be two completely different flavors. All other things the same, by only changing one environmental condition (ex. temperature, pitch rate, fermenter size/dimensions, ect) you will change the beer. This is the primary reason for having temperature control on fermentations. If you don’t have temperature control, your beer will be different every single time, with all other things identical.
So, Brett produces esters, just different esters than lager or ale yeast?
Brett produces esters: some are the same as lager or ale yeast, but others are very different. Here, I will change the comparison. If you use two different varieties of hops in the same recipe, all other things the same, are you expecting the exact same beer? Answer is “no”. OK, this is different because hops aren’t living organisms in beer, but I hope that you can make the connection. As for the ester production, the rate at which and to some extent the esters produced are dependent on the stresses. Temperature is definitely a stress inducing condition as well as many others.
The reason I use hops as an example is because you usually aren’t looking for the same flavor profile as a Saccharomyces fermentation, when you use Brett. I mentioned some of the flavors above in a different answer, but Brett are able to produce compounds that Saccharomyces aren’t able to produce. This includes esters, phenols, organic acids released and a number of other compounds.
So stress and temperature have an impact, but what about pitch rate?
Pitch rate is an interesting topic. As explained earlier, the coolship method of cooling/inoculating wort was the primary way to get Brett into beer. Once modern laboratory practices were introduced, labs began collecting strains and keeping pure cultures. Another way that Brett is introduced into beer is by using oak barrels, which will harbor different yeast and bacteria, depending on the liquid that was kept in them. So, for both the coolship and barrel inoculation, the pitch rate isnot known.
For the use of modern, pure culture inoculation, the brewer is able to pitch at the rate that they want. Of course, just like with traditional Saccharomyces cultures, the pitch rate will affect the compound development during fermentation (both primary and secondary). General guidelines are that if you pitch low, there will be more stress and you will get a wider variety of yeast flavors.
Brett has a reputation for being a very aggressive fermenter, what is meant by that?
The aggressive nature of Brett fermentation can be described a couple of ways. As stated before, Brett can ferment “more completely”, meaning the sugars left behind by Saccharomyces in the same wort. Additionally, Brett forms the pellicle on top of the beer which limits the beer contact with oxygen and keeps the fermentation completely anaerobic. The pellicle will also keep other organisms from entering in a non-sealed container, like an oak barrel (for those who don’t know, oak barrels breathe, think the angels cut in whiskey production). A third way that Brett is aggressive is the speed of multiplication and culturing in either aerobic or anaerobic (the anaerobic cell multiplying is much more aggressive than that of Saccharomyces).
So Brett will attenuate a beer lower than normal ale and lager yeast?
Correct! This is what I mean when I say that Brett will ferment the sugars (carbohydrates) remaining after the Saccharomyces fermentation. Simply speaking, the more sugar that is fermented, the higher the attenuation.
Are there risks involved in using Brettanomyces?
There are huge risks involved in using Brett. When I was brewing professionally, I had three main enemies: lacto, pedio and Brett. If you ever visit production breweries using these organisms and they have a separate room or even building for their barrel aging, this is one of the major reasons why. When you introduce one of these organisms into the brewery (or your homebrewing system), it is very hard to get rid of completely. Once it is in your system, you have to do everything you can to get it out. Lacto, pedio and Brett like to be “that guy” who doesn’t get the point when you try to get rid of him.
Even with strict cleaning procedures, harsh sanitizing procedures and attention paid to all of your equipment, those organisms can hide in soft parts, like gaskets, buckets, cracks, scratches and any other surface or impurity in your system that is difficult to clean. The biggest problem with those organisms is that they will show their ugly/pretty face (depending on your opinion) until you get rid of them completely. They show because, like mentioned before, they ferment things that Saccharomyces do not. So, when you brew your next batch and use a cerevisiae, the cerevisiae finishes the sugar fermentation that it can and then the “wild” organisms finish what’s left.
So what special steps does a home brewer need to take when using Brett?
To be honest (and what I do) is keep it separate. I have a separate fermentation area with separate fermenters. I have a separate bottling bucket and a separate syphon. I KEEP IT SEPARATE. It is the easiest and best way to control those “infections” at home. It costs a little bit more to have separate equipment, but I am confident that I can still produce a clean, uninfected Saccharomyces beer and not have a Brett or lacto or pedio infection!
So guys, as we discussed in our Funkadelic mastery series, you really have to have separate gear if you are using any of the wild yeasts.
Are there any special considerations when packaging or bottling a Brett Beer?
First of all, know that there is the possibility of a pellicle, so if you syphon or when you are transferring, you may move some of that crusty, grey, mold-like cap to a different container. Know that if you don’t filter (I don’t and most homebrewers don’t) that the Brett will still be in the beer and will continue to develop flavors. Know that Brett can ferment more carbohydrates than Saccharomyces, so if you use speise (wort made for priming) or extract or anything of the like, typical calculators will not work. You will need less of any of those than with traditional bottling.
Is wort composition is important?
Wort composition is always important. I think I have said it in previous Q & A’s, but the brewers main jobs are cleaning, sanitizing and preparing the environment for the yeast to be successful in the way that the brewer wants. Your entire job as a brewer is to make the environment that is perfect for the yeast, for the beer that you want. That being said, you have to figure out what you are looking for from the yeast and then brew to produce that environment.
Are mash temperatures then also important?
Always, always, always important. If you mash in at 212dF you will only have the carbohydrates available that are in whole kernel malt. If you mash in at 173dF you will only have the carbohydrates available in whole kernel malt. If you mash at 100dF or 120dF or 151dF or any temperature below 172dF, you will have enzymatic activity from the natural enzymes present in malt (if the malts have diastatic power). I suppose that you could produce a beer by adding enzymes to the wort after that, but most homebrewers don’t have any glucoamylase at home…
We've heard that Brett can have weird reactions with Polyphenols and with Ferulic Acids, can you elaborate on this?
Polyphenols are the precursors for the volatile phenols that Brett produce to make the “Brett” odor. If the wort is lacking the right polyphenols, the Brett cannot change the composition and create those great/horrible odors (again, depends on how you look at it). The Ferulic Acid story is a little different. Brett doesn’t use the Ferulic acid directly to create its fantastic/disgusting (your opinion) flavors. Rather, Brett takes the 4-VG that Saccharomyces produces from Ferulic acid and converts it to 4-EG, one of the, simply put, Brett characters: horse-blanket.
What general advice would you give new and intermediate brewers about brewing an a Brett Beer?
Ok, jokes aside:
(Kevin was joking, but many home brewers who brew Brett or other wild beers, myself included; use an entirely different set up, and minimize soft parts as much as possible. As little tubing as possible, as few rubber gaskets as possible. You have to look at your whole system. We have an auto syphon for clean beer, for brett, and for lactobascilus. We have separate tubing for separate wild fermentations. It never, ever ever gets used for anything but wild beers, and is stored in a different part of the basement. The number one most important thing you can do is never touch any of your wild gear while you are brewing clean beers, and wash and sanitize your hands a lot, Star San does not kill yeast, keep a 10/1 bleach to water spray bottle handy if you brew sours!)
I think the best advice I could give would be to be very thorough with everything involved. There is a reason that most (possibly all) homebrewers don’t start with making Brett beers (at least on purpose!). Generally, brewers can clean and sanitize well enough to get rid of the Brett, but if you can’t you could end up having some “funky” beers or bottles exploding due to over carbonation. Using Brett in your brewery is similar to trying anything new. You have to understand it, apply your understnading, and then experiment with it. Some people do not like the flavors/aromas, others love that character. Some people like super hoppy beer and others hate it. It always comes down to what you want and the best explanation of homebrewing: you do what you want. Brett is slightly different because it could have a lasting impression on other beers, but still, just do what you want in your homebrewing and have fun doing it!
Additional Resources for sour beer
Themadfermentationist.com - Michael Tonsmeier's amazing site about sour beer.
Milk the Funk
Sourbeerblog.com - really gets into the science of sour beers. great starting place.