In Perpetuum: Farmhouse Ale

The scale of most of the homebrew solera projects I’ve read about is beyond my means right now---I don’t have room for a barrel, and it would take me weeks to fill it even if I did.  But there’s no reason not to try something similar on a much smaller scale, and I have a couple of solera-style projects planned for this summer.  This post is about the first: a low gravity, hoppy farmhouse ale based on Jolly Pumpkin’s Bam Biere.

The original batch consists of around 4 gallons of a Bam Biere clone that I brewed at the start of the year.  The plan was to brew 5 gallons and drink it all this summer.  Although five gallons is more than my system can usually handle, I was trying to dial in a BeerSmith set up that would let me liquor down after the mash to reach the full volume for the boil.  Something went wrong, either with the BeerSmith profile or my process on brew day, and I ended up with 4 gallons of 1.042 wort, rather than 5 gallons of 1.037.  I should probably have added water to the fermenter once I realized this, but I decided to just keep the beer as it was.

Fast forward several months, and its time to transfer the beer onto the dry hops.  Rather than doing this with the full batch, I decided to siphon off 3 gallons into a Better Bottle with the dry hops and keep the remaining gallon to cut a second beer.  A few weeks ago I brewed up another batch of the base recipe, but in keeping with the “Farmhouse Ale” moniker, I substituted grains based on what I had available: in place of the flaked barley and Crystal 80 in the original I used unmalted spelt and English Medium Crystal.  Today, after I transferred the 3 gallons of the original onto some Triskel hops, I added around 3.5 gallons of this fully fermented new beer onto the remaining gallon of the original batch. 

My process here is based closely on Ron Jeffries’s at Jolly Pumpkin (which you can now read about in Chapter 5 of American Sour Beers!), but it also fits the practices Yvan de Baets describes in his essay on historical saisons.  At Jolly Pumpkin the fresh beer is fully fermented with a sacchromyces strain before the wild organisms are added by transferring the beer into barrels that have active colonies of brettanomyces and LAB.  This should suit this pseudo-solera style project, since the low gravity of the young beer should prevent the base from getting too sour as it receives fresh batches.  My thought was that I could do a new pull every couple of months, transferring 3 gallons onto (different?) hops and replacing it with another 3 gallons of young beer brewed to a similar recipe with whatever grains I have available.  The result would be a hoppy, sour Farmhouse Ale in perpetuum!

That, at any rate, was the plan.  Unfortunately when I transferred the beer this morning I picked up a bit of acetic character in the base.  Since I was short on the original batch there was a fair bit of head space left in the fermenter, and I’ve definitely opened it once or twice over the last few months to see how it was getting along.  The relatively large amount of oxygen in contact with the beer, combined with the warmer temperatures in the last month or two might have provided the perfect environment for acetobacter to thrive. If that is what’s happened it may only get worse as this second beer ages.  There is still some headspace at the top of the fermenter, and the temperatures are only going to get warmer as the summer progresses (I have limited temperature control beyond my fermentation chamber, so I spend the hot Chicago summers worrying about my sour beers).  One option I might take would be to top the carboy up with another beer so that there was no headspace at all.  From reading American Sour Beers I learnt that Vinnie Cilurzo at Russian River keeps some fairly neutral low gravity beer around for just this purpose.

My original plan was to let this second batch age all summer, but if I don’t top it up what I may do instead (assuming it doesn’t all turn to vinegar!) is pull the next 3 gallons in a month or so and then make sure I have enough to completely fill the fermenter afterwards.  Since the base beer is pretty dry when it goes into the fermenter, I could probably package it on the earlier side if I used heavy bottles and took the remaining gravity points into account.  In fact, since there should be healthy colonies of brettanomyces and LAB in the base beer, it may even be done by then---based on what he says in this interview, I think Ron Jeffries only leaves Bam Biere in barrels for a few weeks.  So I guess I’ll either top it up this week, or open the fermenter again in a month and see what’s happened.

Update: The thought of ending the summer with 5 gallons of malt vinegar has been niggling at me all day.  Luckily, in keeping with my usual practice I saved and strained the left over kettle wort from the rye saison I brewed this weekend to make starters with during the week.  When I got home this afternoon I watered some of this down, boiled it briefly to kill anything that had started to grow in the wort, and topped up the carboy until it was nearly full.  The wort isn’t an exact match to the Farmhouse Ale, but it shouldn’t change the flavours much, especially in such small quantities.  Hopefully the small fermentation caused by the fresh wort will flush any remaining oxygen out of the carboy.  Of course, there’s nothing I can do about the high temperatures that will surely come this summer.