Have you ever wondered how a spontaneously-fermented beer is produced? Well, they don’t just put the wort (unfermented beer) into a regular fermenter and wait for something to happen. It’s a bit more complicated than that. There are biological critters in the air — bacteria and yeast. These microbes are safe to humans and necessary to life as we know it. I have been studying beer extensively for over a decade now and part of that study has been brewing beer at home. I wouldn’t call myself a zymologist, as I tend to leave the scientific method out of my practices. I’m more of a beer artist when it comes to the brews I make at home, focusing more on the process and outcome than knowing exactly which variables cause the results. I like to think about monks brewing in a monastery — it’s not like they had microscopes and pH strips hundreds of years ago. An interesting piece of hardware that the brewers of old did have is a Koelschip, or Coolship, which sounds a lot more high-tech than it actually is. A Coolship is simply a flat open fermenter that resembles an enormous baking pan, or a small swimming pool. The hot wort is pumped into this open fermentation vessel and allowed to cool overnight and naturally become inoculated with wild yeast and bacteria that live in the air. It is then subsequently pumped into barrels, or a secondary fermentation vessel.
I decided this would be fun to try at home on a very small scale — about 2 bottles. What did I use for my Coolship? Well, a baking pan, of course. I have done this several times now with mixed results. I make a small batch of wort with dry malt extract (DME), and add a hop pellet or two (I like to use Citra, one of my favorite hop varieties). Then I set the Coolship next to an open window in my condo in downtown Anchorage, Alaska. Spring and Fall seem to be better times of year for this when I have heard there is more yeast in the air, and the air temperature is neither too hot, nor too cold for the wort to start spontaneously fermenting. I left the Coolship out for 4 nights and then poured the contents into a growler and capped it with an airlock (no need to make vinegar here, I was trying to make beer). The results have been… very interesting. I definitely made a wild beer. The original two bottles were nearly unpalatable (I heard it described as prison beer), but when I made a second generation of the stuff, it started to become a lot more palatable, and arguably delicious! I think the yeast in my Coolship was strained and just needed to become a little more domesticated (and I also added more hops).
There is a fun relationship between hops and yeast. The hops themselves don’t make the yeast start tasting good, it’s the collaborative efforts of the yeast working alongside the hops that make beer tasty. Hops provide nutrition for the yeast. So, I invite you to try this yourself, if you are getting bored of your current beer making procedures. See what kind of flavors live in your part of the ‘hood. I suggest you start your own yeast ranch. All you need is a baking pan! Cheers!