Yes - 20%
No - 79%
I'm surprised (and impressed) that 33 of you have given spontaneous fermentation a shot! The technique is currently only used commercially by the last few Lambic brewers in Belgium and a handful of American bug nerds (the likes of Russian River, Jolly Pumpkin, and Allagash). The general concept is that the boiled wort is exposed to the air, allowing whatever bacteria and wild yeast are present to colonize the beer and ferment it. The results can be mixed, so most breweries that employ spontaneous fermentation rely on blending for consistency and quality.
Despite my love of brewing sour beers so far I've only used microbes obtained from yeast labs and bottle dregs. Introducing added risk by trusting wild yeast for a beer that needs a year or more of age is a bit off-putting for me. That said, I'm considering giving it a shot later this year once cool weather returns (from what I understand the bacteria floating around during hot/damp weather often leads to off flavors).
The closest I've gotten was using a sourdough starter to ferment part of my second batch of Kvass, which is kinda-sorta like a bit like spontaneous fermentation. Speaking of which I was just up in Pittsburgh two weeks ago assisting at East End Brewing on their annual batch of Kvass (more details to come).
I'm also in the process of brewing my first batch soured with microbes harvested from the malt. It isn't exactly a sour mash, but it is in the same direction (souring the wort pre-boil with a starter grown from 1/2 cup of crushed Marris Otter) with a pure strain ale yeast added post-boil to complete the rest of the fermentation.
If you've given ambient/spontaneous fermentation a try please post a comment (or shoot me an email) with your technique and what your result were. I'd also be interested where you left the wort for exposure (orchards/vineyards seems to be a popular choice). As a side note I just noticed Freshops is selling 3 year old Willamette "Lambic" hops.
Saturday, July 3, 2010
Yes - 20%