Kept brewing and thinking about brewing, after that last post. Been meaning to discuss my approach to “brewing bugs”: the yeast and bacteria strains which are involved in some of my beers. So, it’s a kind of follow-up.
Perhaps more than a reason for me to brew, getting to have fun with these living organisms is something of an achievement. It took a while before it started paying off, but it now does.
Now, I’m no biochemist. In fact, I’m fairly far to “wet sciences” in general. What I do with these organisms is based on a very limited understanding of what goes on during fermentation. But as long as I’m having fun, that should be ok.
This blogpost is about yeast in brewing. My focus is on homebrewing but many things also apply to craft brewing or even to macrobreweries.
There’s supposed to be a saying that “brewers make wort, yeast makes beer.” Whether or not it’s an actual saying, it’s quite accurate.
“Wort” is unfermented beer. It’s a liquid containing fermentable sugars and all sorts of other compounds which will make their way into the final beer after the yeast has had its fun in it. It’s a sweet liquid which tastes pretty much like Malta (e.g. Vitamalt).
Yeast is a single-cell organism which can do a number of neat things including the fine act of converting simple sugars into alcohol and CO2. Yeast cells also do a number of other neat (and not so neat) things with the wort, including the creation of a large array of flavour compounds which can radically change the character of the beer. Among the four main ingredients in beer (water, grain, hops, and yeast), I’d say that yeast often makes the largest contribution to the finished beer’s flavour and aroma profile.
The importance of yeast in brewing has been acknowledged to different degrees in history. The well-known Reinheitsgebot “purity law” of 1516, which specifies permissible ingredients in beer, made no mention of yeast. As the story goes, it took Pasteur (and probably others) to discover the role of yeast in brewing. After this “discovery,” Pasteur and others have been active at isolating diverse yeast strains to be used in brewing. Before that time, it seems that yeast was just occurring naturally in the brewing process.
As may be apparent in my tone, I’m somewhat skeptical of the “discovery” narrative. Yeast may not have been understood very clearly before Pasteur came on the scene, but there’s some evidence showing that yeast’s contribution to brewing had been known in different places at previous points in history. It also seems likely that multiple people had the same basic insight as LP did but may not have had the evidence to support this insight. This narrative is part of the (home)brewing “shared knowledge.”
But I’m getting ahead of myself.
There’s a lot to be said about yeast biochemistry. In fact, the most casual of brewers who spends any significant amount of time with online brewing resources has some understanding, albeit fragmentary, of diverse dimensions of biochemistry through the action of yeast. But this blogpost isn’t about yeast biochemistry.
I’m no expert and biochemistry is a field for experts. What tends to interest me more than the hard science on yeast is the kind of “folk science” brewers create around yeast. Even the most scientific of brewers occasionally talks about yeast in a way which sounds more like folk beliefs than like hard science. In ethnographic disciplines, there’s a field of “ethnoscience” which deals with this kind of “folk knowledge.” My characterization of “folk yeast science” will probably sound overly simplistic and I’m not saying that it accurately represents a common approach to yeast among brewers. It’s more in line with the tone of Horace Miner’s classic text about the Nacirema than with anything else. A caricature, maybe, but one which can provide some insight.
In this case, because it’s a post on my personal blog, it probably provides more insight about yours truly than about anybody else. So be it.
I’m probably more naïve than most. Or, at least, I try to maintain a sense of wonder, as I play with yeast. I’ve done just enough reading about biochemistry to be dangerous. Again, “the brewery is an adult’s chemistry set.”
A broad distinction in the brewer’s approach to yeast is between “pure” and “wild” yeast. Pure yeast usually comes to the brewer from a manufacturer but it originated in a well-known brewery. Wild yeast comes from the environment and should be avoided at all costs. Wild yeast infects and spoils the wort. Pure yeast is a brewer’s best friend as it’s the one which transforms sweet wort into tasty, alcoholic beer. Brewers do everything to “keep the yeast happy.” Though yeast happiness sounds like exaggeration on my part, this kind of anthropomorphic concept is clearly visible in discussions among brewers. (Certainly, “yeast health” is a common concept. It’s not anthropomorphic by itself, but it takes part in the brewer’s approach to yeast as life.) Wild yeast is the reason brewers use sanitizing agents. Pure yeast is carefully handled, preserved, “cultured.” In this context, “wild yeast” is unwanted yeast. “Pure yeast” is the desirable portion of microflora.
It wouldn’t be too much of an exaggeration to say that many brewers are obsessed with the careful handling of pure yeast and the complete avoidance of wild yeast. The homebrewer’s motto, following Charlie Papazian, may be “Relax, Don’t Worry, Have a Homebrew,” when brewers do worry, they often worry about keeping their yeast as pure as possible or keeping their wort as devoid of wild yeast as possible.
In the context of brewers’ folk taxonomy, wild yeast is functionally a “pest,” its impact is largely seen as negative. Pure yeast is beneficial. Terms like “bugs” or “beasties” are applied to both but, with wild yeast, their connotations and associations are negative (“nasty bugs”) while the terms are applied to pure yeast in a more playful, almost endeared tone. “Yeasties” is almost a pet name for pure yeast.
I’ve mentioned “folk taxonomy.” Here, I’m mostly thinking about cognitive anthropology. Taxonomies have been the hallmark of cognitive anthropology, as they reveal a lot about the ways people conceive of diverse parts of reality and are relatively easy to study. Eliciting categories in a folk taxonomy is a relatively simple exercise which can even lead to other interesting things in terms of ethnographic research (including, for instance, establishing rapport with local experts or providing a useful basis to understanding subtleties in the local language). I use terms like “folk” and “local” in a rather vague way. The distinction is often with “Western” or even “scientific.” Given the fact that brewing in North America has some strong underpinnings in science, it’s quite fun to think about North American homebrewers through a model which involves an opposition to “Western/scientific.” Brewers, including a large proportion of homebrewers, tend to be almost stereotypically Western and to work through (and sometimes labour under) an almost-reductionist scientific mindframe. In other words, my talking about “folk taxonomy” is almost a way to tease brewers. But it also relates to my academic interest in cultural diversity, language, worldviews, and humanism.
“Folk taxonomies” can be somewhat fluid but the concept applies mostly to classification systems which are tree-like, with “branches” coming of broader categories. The term “folksonomy” has some currency, these days, to refer to a classification structure which has some relation to folk taxonomy but which doesn’t tend to work through a very clear arborescence. In many contexts, “folksonomy” simply means “tagging,” with the notion that it’s a free-form classification, not amenable to treatment in the usual “hierarchical database” format. Examples of folksonomies often have to do with the way people classify books or other sources of information. A folksonomy is then the opposite of the classification system used in libraries or in Web directories such as the original Yahoo! site. Tags assigned to this blogpost (“Tagged: Belgian artist…”) are part of my own folksonomy for blogposts. Categories on WordPress blogs such as this ones are supposed to create more of a (folk) taxonomy. For several reasons (including the fact that tags weren’t originally available to me for this blog), I tend to use categories as more of a folksonomy, but with a bit more structure. Categories are more stable than tags. For a while, now, I’ve refrained from adding new categories (to my already overly-long list). But I do add lots of new tags.
Going back to brewers’ folk taxonomy of yeast strains…
Technically, if I’m not mistaken, the term “pure” should probably refer to the yeast culture, not to the yeast itself. But the overall concept does seem to apply to types of yeast, even if other terms are used. The terms “wild” and “pure” aren’t inappropriate. “Wild” yeast is undomesticated. “Pure” yeast strains were those strains which were selected from wild yeast strains and were isolated in laboratories.
Typically, pure yeast strains come from one of two species of the genus Saccharomyces. One species includes the “top-fermenting” yeast strains used in ales while the other species includes the “bottom-fermenting” yeast strains used in lagers. The distinction between ale and lager is relatively recent, in terms of brewing history, but it’s one which is well-known among brewers. The “ale” species is called cerevisiae (with all sorts of common misspellings) and the “lager” species has been called different names through history, to the extent that the most appropriate name (pastorianus) seems to be the object of specialized, not of common knowledge.
“Wild yeast” can be any yeast strain. In fact, the two species of pure yeast used in brewing exist as wild yeast and brewers’ “folk classification” of microorganisms often lumps bacteria in the “wild yeast” category. The distinction between bacteria and yeast appears relatively unimportant in relation to brewing.
As can be expected from my emphasis on “typically,” above, not all pure yeast strains belong to the “ale” and “lager” species. And as is often the case in research, the exceptions are where things get interesting.
One category of yeast which is indeed pure but which doesn’t belong to one of the two species is wine yeast. While brewers do occasionally use strains of wild yeast when making other beverages besides beer, wine yeast strains mostly don’t appear on the beer brewer’s radar as being important or interesting. Unlike wild yeast, it shouldn’t be avoided at all costs. Unlike pure yeast, it shouldn’t be cherished. In this sense, it could almost serve as «degré zéro» or “null” in the brewer’s yeast taxonomy.
Then, there are yeast strains which are usually considered in a negative way but which are treated as pure strains. I’m mostly thinking about two of the main species in the Brettanomyces genus, commonly referred to as “Brett.” These are winemakers’ pests, especially in the case of oak aging. Oak casks are expensive and they can be ruined by Brett infections. In beer, while Brett strains are usually classified as wild yeast, some breweries have been using Brett in fermentation to effects which are considered by some people to be rather positive while others find these flavours and aromas quite displeasing. It’s part of the brewing discourse to use “barnyard” and “horse blanket” as descriptors for some of the aroma and flavour characteristics given by Brett.
Brewers who consciously involve Brett in the fermentation process are rather uncommon. There are a few breweries in Belgium which make use of Brett, mostly in lambic beers which are fermented “spontaneously” (without the use of controlled innoculation). And there’s a (slightly) growing trend among North American home- and craft brewers toward using Brett and other bugs in brewing.
Because of these North American brewers, Brett strains are now available commercially, as “pure” strains.
Which makes for something quite interesting. Brett is now part of the “pure yeast” category, at least for some brewers. They then use Brett as they would other pure strains, taking precautions to make sure it’s not contaminated. At the same time, Brett is often used in conjunction with other yeast strains and, contrary to the large majority of beer fermentation methods, what brewers use is a complex yeast culture which includes both Saccharomyces and Brett. It may not seem that significant but it brings fermentation out of the strict “mono-yeast” model. Talking about “miscegenation” in social terms would be abusive. But it’s interesting to notice which brewers use Brett in this way. In some sense, it’s an attitude which has dimensions from both the “Belgian Artist” and “German Engineer” poles in my brewing attitude continuum.
Other brewers use Brett in a more carefree way. Since Brett-brewing is based on a complex culture, one can go all the way and mix other bugs. Because Brett has been mostly associated with lambic brewing, since the onset of “pure yeast” brewing, the complex cultures used in lambic breweries serve as the main model. In those breweries, little control can be applied to the balance between yeast strains and the concept of “pure yeast” seems quite foreign. I’ve never visited a lambic brewery (worse yet, I’ve yet to set foot in Belgium), but I get to hear and read a lot about lambic brewing. My perception might be inaccurate, but it also reflects “common knowledge” among North American brewers.
As you might guess, by now, I take part in the trend to brew carefreely. Even carelessly. Which makes me more of a MadMan than the majority of brewers.
Among both winemakers and beer brewers, Brett has the reputation to be “resilient.” Once Brett takes hold of your winery or brewery, it’s hard to get rid of it. Common knowledge about Brett includes different things about its behaviour in the fermentation process (it eats some sugars that Saccharomyces doesn’t, it takes a while to do its work…). But Brett also has a kind of “character,” in an almost-psychological sense.
Which reminds me of a comment by a pro brewer about a well-known strain of lager yeast being “wimpy,” especially in comparison with some well-known British ale yeast strains such as Ringwood. To do their work properly, lager strains tend to require more care than ale strains, for several reasons. Ringwood and some other strains are fast fermenters and tend to “take over,” leaving little room for other bugs.
Come to think of it, I should try brewing with a blend of Ringwood and Brett. It’d be interesting to see “who wins.”
Which brings me to “war.”
Now, I’m as much of a pacifist as one can be. Not only do I not tend to be bellicose and do I cherish peace, I frequently try to avoid conflict and I even believe that there’s a peaceful resolution to most situations.
Yet, one thing I enjoy about brewing is to play with conflicting yeast strains. Pitting one strain against another is my way to “wage wars.” And it’s not very violent.
I also tend to enjoy some games which involve a bit of conflict, including Diplomacy and Civilization. But I tend to play these games as peacefully as possible. Even Spymaster, which rapidly became focused on aggressions, I’ve been playing as a peace-loving, happy-go-lucky character.
But, in the brewery, I kinda like the fact that yeast cells from different strains are “fighting” one another. I don’t picture yeast cells like warriors (with tiny helmets), but I