Soaked some decomposing oak leaves for 36 hours in preboiled water with some yeast flakes. Stirred, put 1-2 ml into test tubes with 5 ml of malt beer ("Karamalz", I just picked a random brand), filled up with equal amounts of 5 % vinegar and whisky (didn’t have any vodka at hand). Put a thin layer of neutral vegetable oil on top.
Should keep out the vast majority of bad microbes and provide a mostly oxygen free environment for yeast.
IIRC, I’ve also read on suigeneris brewing that oak leaf litter has a 50 - 80 % chance of catching bretanomyce, which I’d be thrilled to find.
If you are really interested in capturing wild yeast I would recommend reading Wild Crafting Brewer. There's a ton of information on great wild yeast sources.
I don't think oak leaves were a specific example but it's everywhere. He recommend flowers, fruit and pinecones as great sources
Thanks for the hint! I don’t see myself having time for an entire book anytime soon, but I’ll certainly put it on my list.
The oak litter idea stems from more recent studies where IIRC they found that brettanomyce is rarely found on the skins of fruit, only in vineyards where they dump their pomace (?) below the actual tendrils, but in forest floors and most particularly in oak litter.
If you’re interested, I posted a link to a video by suigeneris brewing where Bryan explains just the above somewhere here in the thread.
I'm sure it's going to work great. Wild yeasts are everywhere.
I recommend that book because it's all about brewing with things you forage using simple brewing methods. So you won't find a recipe for a traditional "beer" but lots of things like lemon and mugwort "beer". I got it this winter and can't wait to try it out