Yeast plays a pretty central role in brewing beer. In fact, were it not for these tiny fungi (yeast is a fungus, not a bacteria), there would be no beer. There would be no wine or mead, either. Even most types of bread would be problematic. However, not all yeast is created equal. While it’s absolutely critical to creating beer, many breweries are tinkering with their cash cow. They’re going wild.
The Reality of Yeast
Most breweries, both craft and Big Beer, use a “house yeast”. That is, they use a strain of yeast, usually purchased commercially from a yeast production lab like Wyeast, that has been adapted to their production facility. Creating an in-house strain from a commercial yeast doesn’t take all that long and isn’t really all that difficult. It just takes brewing beer, harvesting yeast from the fermenter, revitalizing it, and then repeating the process many times.
Eventually, the yeast adapts to the water and brewing conditions specific to that one brewery, and it becomes a house strain. Some breweries don’t bother with house strains. The cost of yeast from labs has come down in recent years, and, lacking the facilities to harvest, wash and store yeast, some breweries just purchase from the labs over and over again.
Here’s the thing, though. Yeast is all around us. It’s in the air. It’s on our skin. It’s inside our bodies. Yes, the yeast used for brewing beer (and for baking yeast breads) is quite literally everywhere.
This is called “wild” yeast. That is, it’s yeast that was not captured and then bred over successive generations to focus on desirable characteristics and to weed out unwanted ones. This is what brewers used to ferment their beer for most of its 6,000-year history.
Today’s craft breweries are starting to focus more on these wild yeasts. Why in the world would they do that when they have commercial yeasts available?
A Connection to the Past
As mentioned, brewers only recently gained access to commercial yeast. Before that, they were at their mercy of the environment. They were forced to allow wild yeast to ferment their beer (and the same was true with bread making, wine making and mead making).
In fact, prior to the identification of microorganisms, it wasn’t even known that yeast was needed for fermentation to take place (no one knew what yeasts were). If you examine the very earliest versions of the Reinheitsgebot, you’ll find that it lists water, barley and hops as the three ingredients of beer. Yeast isn’t on the list.
So, many craft brewers are using wild yeasts in an attempt to connect with the roots of their art. In some instances, this is done in conjunction with an ancient recipe for beer. In others, it’s done just to see what wild yeast can bring to a modern recipe, or to learn more about what ancient brewers went through in pursuit of their art.
It’s the Style
Some beer styles require the use of wild yeast, and possibly some other microorganisms. Take lambics as an example. They use far more than just saccharomyces. You’ll find brettanomyces in the mix, as well as lactic acid bacteria (lactobacillus – the same bacteria responsible for helping to create kimchi and sauerkraut), and many other tiny invisible helpers.
Lambics are not the only style of beer that relies on wild yeasts to give them their trademark flavor – virtually any Belgian beer requires the use of wild yeast to create the funk that they’re so well known for. Berliner weisse is another beer that relies on wild yeast.
Wild yeast goes well beyond the range of sour beers that are so popular today. It can be used to create funky beers, as well as those with a slightly tamer taste, more in line with what consumers are accustomed to enjoying.
They’re Capturing Terroir
Terroir is French, and means “the character or essence of a place”. There’s a huge push toward “going local” in the craft beer industry and in many other areas of the economy. Brewers are trying to use locally grown grains, locally grown hops (where possible), and locally sourced ingredients to create a truly authentic regional brew.
Harvesting wild yeast from the air around a brewer ties directly into that. It doesn’t get much more local, actually. When brewers are able to combine locally sourced ingredients with wild yeast captured in the area, they can truly create a beer that exhibits the terroir of the area – the taste and flavor of that specific place, at that specific time.
How Is Wild Yeast Captured?
Capturing wild yeast isn’t as difficult as it sounds. Obviously, it can’t be that hard or beer would never have been reliably brewed in the distant past. Bread makers using wild yeast to create a sourdough starter do much the same thing today (and saccharomyces is the yeast of choice for both beer and bread). However, it’s also not that simple. Yes, you can set out a container with wort and wait for the tiny beasties to colonize it, but there’s really no telling what you’ll get that way.
While some breweries do catch wild yeast the old-fashioned way, many have moved to a more high-tech method. They capture yeast from the air, or from flowers growing in the area, and then have those sorted, developed, studied and cataloged by a local laboratory. This allows them to identify the various types of yeast captured, which ones would be best suited to their brewing needs, and then create and maintain a stable of yeasts for use.
What are your thoughts? Do you enjoy beers brewed with wild yeast? Do you prefer sours? Lambics? Belgians? Something else? Chime in below and let us know.