Community is a big focus for Council Brewing (we even mention it on every label) and this beer story exemplifies that. We are especially close to the homebrew community, more specifically the QUAFF Homebrew club. It's the reason that Liz, Curtis and myself (Jeff) all met in the first place. At one of the club meetings last Fall, some of our fellow members (Stan Sisson and Brian Kenner) were discussing their new venture, Julian Ciderworks and how they were starting to work with another member, Curt Wittenberg of Terrior Biologics, to isolate wild yeast. Curt, a yeast molecular biologist had already isolated a few yeast strains and together with Stan had started some small scale trials. Needless to say, we were excited to try these ciders and taste some domesticated wild yeast from our community.
The pilot batches were all promising, even a bit cleaner tasting than one would romanticize about the taste of wild yeast. Although, ciders tend not to be as expressive as beer due to the simple sugars and lack of other flavor precursors. From this point we set a date to get some pomace (the dried apple pulp leftover from the juice pressing) delivered fresh and to brew a pilot beer batch with one of Curt's isolated yeast strains.
We received a 5 gal bucket of 2 apple varieties, Arkansas Black and Winesop. Those buckets were immediately re-hydrated with a simple un-hopped starter wort. Only about a gallon of wort was absorbed before filling the bucket and then on went the lid and airlock.
Now seems appropriate to discuss some theory behind this technique. The idea was to learn from history, people were making cider hundreds of years ago without commercial yeast labs and many of those ciders (think Spanish sidre) still exist, so there must be some promise to this method.. Along these lines, wine pomace would also make an excellent starter material to harvest your own wild yeast. The science behind using pomace as a starter is that you are harvesting from a low pH environment (check the pictures above for the stats) that is an unwelcome environment for many poor tasting organisms. And if you can do your best to reduce the exposure to oxygen you can also increase your odds for a pleasant tasting product.
In order to reduce the level of oxygen exposure, it is best to strain the fermenting wort off the pomace as soon as you see some activity. If you wait until fermentation dies down then you risk mold occurring on the top layer where the apple chunks dry out. Mold needs a specific moisture level to form, which is more likely to occur when debris is on the surface. (If you are familiar with fermenting foods this is why a weight is used to ensure a liquid layer is always above the food). Once in a container that could be fitted with an airlock, additional wort was added. This time moderately hopped wort (25 IBUS, 1.040) was used to encourage yeast growth over bacterial growth. Each starter ended up with about a 1 gal total volume. (a lot of the original volume remains in the pomace, but was strained as best as possible).
After the fermentation had settled in the new starters (about 7-10 days), it was finally time to taste and measure the gravity. Both tasted relatively clean still (which was welcome, considering some "rubber band" tasting trials I've done with the traditional coolship method) and to the biggest surprise had about 75% attenuation so far. This was exciting news as a major concern with harvesting yeast from apples is that you may only get yeast that can ferment simple sugars and not the complex sugars found in beer wort.
The final step was to do one more additional step-up (and we ended up combining the two apple varieties) to get enough yeast to ferment a 3 BBL pilot batch at Council. We used a fairly simple, Saison-esque, recipe as we wanted the yeast to shine. After many months of aging, we were pleasantly rewarded with a flavor profile that has a nice balance of fruity esters (apple actually) and light phenolic spicy notes. No noticeable acidity and an incredibly dry finish.
If you want to taste it for yourself and also listen to a presentation with more details (as well as a couple other methods) for harvesting wild yeast, please join us Wednesday evening, 9/14 at 5:30 pm in Council Brewing tasting room.
-Jeff "Wild Man" Crane