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.

Anyhoo…

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 do have fun imagining the “Battle of the Yeast.”

Of course, this has more to do with competition than with conflict. But both are related, in my mind. I’m also not that much into competition and I don’t like to pit people against one another, even in friendly competition. But this is darwinian competition. True “survival of the fittest,” with everything which is implied in terms of being contextually appropriate.

So I’m playing with life, in my brewery. I’m not acting as a Creator over the yeast population, but there’s something about letting yeast cells “having at it” while exercising some level of control that could be compared to some spiritual figures.

Thinking about this also makes me think about the Life game. There are some similarities between what goes on in my wort and what Conway’s game implies. But there are also several differences, including the type of control which can be applied in either case and the fact that the interaction between yeast cells is difficult to visualize. Not to mention that yeast cells are actual, living organisms while the cellular automaton is pure simulation.

The fun I have playing with yeast cells is part of the reason I like to use Brett in my beers. The main reason, though, is that I like the taste of Brett in beer. In fact, I even like it in wine, by transfer from my taste for Brett in beer.

And then, there’s carefree brewing.

As I described above, brewers are very careful to avoid wild yeast and other unwanted bugs in their beers. Sanitizing agents are an important part of the brewer’s arsenal. Which goes well with the “German engineer” dimension of brewing. There’s an extreme position in brewing, even in homebrewing. The “full-sanitization brewery.” Apart from pure yeast, nothing should live in the wort. Actually, nothing else should live in the brewery. If it weren’t for the need to use yeast in the fermentation process, brewing could be done in a completely sterile environment. The reference for this type of brewery is the “wet science” lab. As much as possible, wort shouldn’t come in contact with air (oxidization is another reason behind this; the obsession with bugs and the distaste for oxidization often go together). It’s all about control.

There’s an obvious reason behind this. Wort is exactly the kind of thing wild yeast and other bugs really like. Apparently, slants used to culture microorganisms in labs may contain a malt-based gelatin which is fairly similar to wort. I don’t think it contains hops, but hops are an agent of preservation and could have a positive effect in such a slant.

I keep talking about “wild yeast and other bugs” and I mentioned that, in the brewer’s folk taxonomy, bacteria are equivalent to wild yeast. The distinction between yeast and bacteria matters much less in the brewery than in relation to life sciences. In the conceptual system behind brewing, bacteria is functionally equivalent to wild yeast.

Fear of bacteria and microbes is widespread, in North America. Obviously, there are many excellent medical reasons to fear a number of microorganisms. Bacteria can in fact be deadly, in the right context. Not that the mere presence of bacteria is directly linked with human death. But there’s a clear association, in a number of North American minds, between bacteria and disease.

As a North American, despite my European background, I tended to perceive bacteria in a very negative way. Even today, I react “viscerally” at the mention of bacteria. Though I know that bacteria may in fact be beneficial to human health and that the human body contains a large number of bacterial cells, I have this kind of ingrained fear of bacteria. I love cheese and yogurt, including those which are made with very complex bacterial culture. But even the mere mention of bacteria in this context requires that I think about the distinction between beneficial and dangerous bacteria. In other words, I can admit that I have an irrational fear of bacteria. I can go beyond it, but my conception of microflora is skewed.

For two years in Indiana, I was living with a doctoral student in biochemistry. Though we haven’t spent that much time talking about microorganisms, I was probably influenced by his attitude toward sanitization. What’s funny, though, is that our house wasn’t among the cleanest in which I’ve lived. In terms of “sanitary conditions,” I’ve had much better and a bit worse. (I’ve lived in a house where we received an eviction notice from the county based on safety hazards in that place. Lots of problems with flooding, mould, etc.)

Like most other North American brewers, I used to obsess about sanitization, at every step in the process. I was doing an average job at sanitization and didn’t seem to get any obvious infection. I did get “gushers” (beers which gush out of the bottle when I open it) and a few “bottle bombs” (beer bottles which actually explode). But there were other explanations behind those occurrences than contamination.

The practise of sanitizing everything in the brewery had some significance in other parts of my life. For instance, I tend to think about dishes and dishwashing in a way which has more to do with caution over potential contamination than with dishes appearing clean and/or shiny. I also think about what should be put in the refrigerator and what can be left out, based on my limited understanding of biochemistry. And I think about food safety in a specific way.

In the brewery, however, I moved more and more toward another approach to microflora. Again, a more carefree approach to brewing. And I’m getting results that I enjoy while having a lot of fun. This approach is also based on my pseudo-biochemistry.

One thing is that, in brewing, we usually boil the wort for an hour or more before inoculation with pure yeast. As boiling kills most bugs, there’s something to be said about sanitization being mostly need for equipment which touches the wort after the boil. Part of the equipment is sanitized during the boiling process and what bugs other pieces of equipment may transfer to the wort before boiling are unlikely to have negative effects on the finished beer. With this idea in mind, I became increasingly careless with some pieces of my brewing equipment. Starting with the immersion chiller and kettle, going all the way to the mashtun.

Then, there’s the fact that I use wild yeast in some fermentations. In both brewing and baking, actually. Though my results with completely “wild” fermentations have been mixed to unsatisfactory, some of my results with “partially-wild” fermentations have been quite good.

Common knowledge among brewers is that “no known pathogen can survive in beer.” From a food safety standpoint, beer is “safe” for four main reasons: boiling, alcohol, low pH, and hops. At least, that’s what is shared among brewers, with narratives about diverse historical figures who saved whole populations through beer, making water sanitary. Depending on people’s attitudes toward alcohol, these stories about beer may have different connotations. But it does seem historically accurate to say that beer played an important part in making water drinkable.

So, even wild fermentation is considered safe. People may still get anxious but, apart from off-flavours, the notion is that contaminated beer can do no more harm than other beers.

The most harmful products of fermentation about which brewers may talk are fusel alcohols. These, brewers say, may cause headaches if you get too much of them. Fusels can cause some unwanted consequences, but they’re not living organisms and won’t spread as a disease. In brewer common knowledge, “fusels” mostly have to do with beers with high degrees of alcohol which have been fermented at a high temperature. My personal sense is that fusels aren’t more likely to occur in wild fermentation than with pure fermentation, especially given the fact that most wild fermentation happens with beer with a low degree of alcohol.

Most of the “risks” associated with wild fermentation have to do with flavours and aromas which may be displeasing. Many of these have to do with souring, as some bugs transform different compounds (alcohol especially, if I’m not mistaken) into different types of acids. While Brett and other strains of wild yeast can cause some souring, the acids in questions mostly have to do with bacteria. For instance, lactobacillus creates lactic acid, acetobacter creates acetic acid, etc.

Not only do I like that flavour and aroma characteristics associated with some wild yeast strains (Brett, especially), I also like sour beers. It may sound strange given the fact that I suffer from GERD. But I don’t overindulge in sour beers. I rarely drink large quantities of beer and sour beers would be the last thing I’d drink large quantities of. Besides, there’s a lot to be said about balance in pH. I may be off but I get the impression that there are times in which sour things are either beneficial to me or at least harmless. Part of brewer common knowledge in fact has a whole thing about alkalinity and pH. I’m not exactly clear on how it affects my body based on ingestion of diverse substances, but I’m probably affected by my background as a homebrewer.

Despite my taste for sour beers, I don’t necessarily have the same reaction to all souring agents. For instance, I have a fairly clear threshold in terms of acetic acid in beer. I enjoy it when a sour beer has some acetic character. But I prefer to limit the “aceticness” of my beers. Two batches I’ve fermented with wild bugs were way too acetic for me and I’m now concerned that other beers may develop the same character. In fact, if there’s a way to prevent acetobacter from getting in my wort while still getting the other bugs working, I could be even more carefree as a brewer than I currently am.

Which is a fair deal. These days, I really am brewing carefreely. Partly because of my “discovery” of lactobacillus.

As brewer common knowledge has it, lactobacillus is just about everywhere. It’s certainly found on grain and it’s present in human saliva. It’s involved in some dairy fermentation and it’s probably the main source of bacterial fear among dairy farmers.

Apart from lambic beers (which all come from a specific region in Belgium), the main sour beer that is part of brewer knowledge is Berliner Weisse. Though I have little data on how Berliner Weisse is fermented, I’ve known for a while that some people create a beer akin to Berliner Weisse through what brewers call a “sour mash” (and which may or may not be related to sour mash in American whiskey production). After thinking about it for years, I’ve done my first sour mash last year. I wasn’t very careful in doing it but I got satisfying results. One advantage of the sour mash is that it happens before boiling, which means that the production of acid can be controlled, to a certain degree. While I did boil my wort coming from sour mash, it’s clear that I still had some lactobacillus in my fermenters. It’s possible that my boil (which was much shorter than the usual) wasn’t enough to kill all the bugs. But, come to think of it, I may have been a bit careless with sanitization of some pieces of equipment which had touched the sour wort before boiling. Whatever the cause, I ended up with some souring bugs in my fermentation. And these worked really well for what I wanted. So much so that I’ve consciously reused that culture in some of my most recent brewing experiments.

So, in my case, lactobacillus is in the “desirable” category of yeast taxonomy. With Brett and diverse Saccharomyces strains, lactobacillus is part of my fermentation apparatus.

As a mad brewer, I can use what I want to use. I may not create life, but I create beer out of this increasingly complex microflora which has been taking over my brewery.

And I’m a happy brewer.