Open-Fermented or Native Yeast Beers

Answering my own question a year later.

I've achieved this successfully by culturing a native wine yeast and then building it up via making multiple starters with DME:

Mash up some ripe wine grapes really well and then press off the juice. Say 5 gallons or so. By ripe, I mean 24 brix or so (~1.100 SG). Check the pH. If it's under 3.8, your safe, otherwise add tartaric acid until your pH is between 3.2 and 3.8. Put the juice in some kind of open container, with cheesecloth over it to keep the flies out. Leave the container at room temperature for a week or so. It will ferment on its own. Drop a pinch of Fermaid K in there at the beginning of fermentation.

When it's done fermenting, pour the wine off the lees (yeast sediment). Now cook up some DME in a quart or two of water. Cool it to 70ºF/21ºC and pitch your new lees into it. Cover the sanitized container with foil or an airlock and let 'er rip. You may need to repeat this a couple of times if your first starter has a funky wine color you don't want in your beer.

The resulting starter is a native yeast starter you can safely use in your beer. The low pH of wine grapes + the high alcohol usually prevents the growth of the worst of the spoilage bacteria. You might get some brett in there though... depending on what lurks in your vineyard or your house or wherever you let the native yeast rip.

Episode 42 of Brewing TV has Jeremy King harvesting wild yeast. One process is described at 5min 15sec in the video, but was basically:

He steeped 6 kernels of barley in 4ml of wort. Then over time repeatedly doubled the wort till final reaching 5 US gal. That resulted in three living organisms in the beer (one bacteria and two wild yeasts). This couldn't ferment beyond 3% alcohol, so he killed off the bacteria with chlorine dioxide and sent the yeast samples away to a lab. The lab isolated the two yeasts. One tasted horrible but the other was usable.

I've made sourdough starter with organic whole-grain flour, as well as one with rye flour. Here's how I made it:

1. Mix the flour with water.
2. Cover and let it develop for 12 hours in dark, draft-free place.
3. Remove half of it, replenish with fresh flour and water, then back to step 1.
4. Once the starter double's itself every 12 hours you start replenishing with white flour.
5. After yeast is a week old and still going strong, it's safe to use.

Like with the grapes you mentioned, this works because of the natural yeast from the fields it was grown in lives on the wheat or rye. I would be willing to bet that similarly, yeast lives on the barley, however, since the barley used in brewing has been malted all of the yeast is killed off.

I think you'd have to get the yeast using unmalted barley or organic barley flour, and along with it you'd probably pick up some Lactobacillus as you do in sourdough. This would give you that distinct sour flavor by producing lactic acid during your fermentation.

Also, as you mentioned, the vigorous boiling will kill any yeast off, so you must figure out how to: introduce barley and its yeast to a prime growing environment, crowd out any other bacteria that might be living on the barley, stabilize the yeast strain, and pitch it after your wort has cooled to room temperature.

I would just get a yeast culture the same way you do with bread (of course being more carefull and sanitary):

1. Mix some finely-ground barley/organic barley flour (unmalted would render the best results I imagine) with water (maybe some liquid malt extract as well to feed the yeast?).
2. Put in a sanitized container with an airlock or in an air-tight container and let it develop for 12 hours in dark, draft-free place.
3. Remove half of it, replenish with fresh finely-ground barley/organic barley flour and water (lme?), then back to step 1.
4. Once the starter is going strong (lots of CO2 and activity) you start replenishing with malt extract only so you don't introduce any more foreign organisms.
5. After yeast is a week old and still going strong (and doesn't smell funky), it's safe to use.

You pose a very interesting question and I am very tempted to try this myself. It works with bread, why not beer? I think the key is going to be to get the yeast culture up and going long enough to crowd out any other organisms that might be living in there. If you find a good strain, just keep it alive and reuse it!

Let us know if you try something out and how it went!

I made a great sourdough starter from plumbs growing near my apartment. I prepared a normal water/flour mixture, then put about a half-dozen plumbs in it. They all had that white yeast layer like you see on grapes. After a couple of days, when the plumbs got squishy and it was time to feed the starter again, I mashed the plumbs up to release the sugar.

You could do the same thing for your beer. Find fruit trees growing nearby or maybe some good organic fruits with the yeast still growing on them. Make a yeast starter like you normally would with beer yeast, but put the fruit in it. Might be tasty.