Thursday, June 9, 2011

Taming wild yeast

As my appreciation for and intrigue by "wild ales" has grown, I've been more and more interested in trying my hand at brewing a batch of beer with local, wild yeast. I originally thought I would try it the old school way by brewing up some wort and then setting it outside, open to the elements (and airborne microbes) to cool and see what I get with the resulting beer. But then I read a post by the Mad Fermentationist about collecting wild yeast using a simple starter technique and I was inspired to try something similar. Why waste a whole batch of beer when you have no idea what yeast/bacteria/mold might jump in?

So, after I realized I had a few cups of runnings left in the mash tun from brewing the "luau beer", I decided here was a great opportunity to try my luck. I diluted the runnings down to a gravity of about 1.030, boiled it for ~15 minutes with a couple grams of old Tettnang pellet hops, threw it in a bowl and covered it with some cheesecloth. I then placed the covered bowl of wort in my backyard in little wooded patch, under some oak trees. I let it sit there overnight. In the morning, I transferred the wort to a sanitized jug and affixed an airlock.

After a few days, I started to see a slight white foam forming on the surface of the wort. I wasn't sure if it was yeast or mold or what, so I just let it go, hoping to get some sort of krausen and some airlock activity to convince me I had something worthwhile. I never saw anything like that though. I'm guessing now that the relatively small number of cells, the low gravity wort, and the large amount of head space in the container just wasn't conducive to me seeing much activity.

With some advice from "Mad Mikey T.", I boiled up a couple cups of starter wort with some DME (1.040) and added that to the jug. This time though, I ditched the airlock and gave the jug a good shake/swirl every so often - just like I would do with a regular yeast starter. Well, much to my delight the starter took off and I had a nice foamy krausen after a couple of days. It smelled pretty good too - yeasty, of course, but also slightly fruity and a bit spicy. I think I have something to work with here! The gravity of the starter came down to 1.012 as of this evening. I ventured a taste of the hydrometer sample and I have to say I think this experiment could pan out - although pretty mellow, I definitely got hints of clove and pepper and some underlying fruitiness.

So now I know what my next brew is going to be - a local New England Saison (not yet an official BJCP style). Hopefully I will be able to get to this in the next week or so - I don't want to lose this yeast before I get to try it out. Stay tuned!


Unknown said...

any updates on this project? im thinking of doing the samething.

Jim Lemire said...

The beer turned out pretty well for an experiment of this type. My tasting notes and thoughts on the beer are here -

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