Lowering Gravity With Brett

It's true, good things do come to those who wait, at least this time, and here's why. I took an under-attenuated beer that I thought was destined for that long slow pour down the drain and instead, created something wonderful.

First, a little background history. Back in November of 2011, I was getting ready for my return to San Miguel for the Winter and so was brewing a series of lagers that would age in cold storage here in Santa Cruz for the 5 months that I would be gone. My plan was to come back to a set of delicious beers including a schwarzbier, bock, dopplebock and a Munich dunkel. All went well with the exception of the dunkel which simply would not ferment lower than 55% of it's original gravity. (I discovered much later that I may have mashed at a higher then presumed temperature because my thermometer was out of calibration. While it read 152f. the actual temperature was in all likelihood 158f.)
Unfermentables or long chains of sugar molecules left in solution due to a high mash temperature I believe was the problem although I suspect that a low pitch amount was also a contributing factor. I only stepped my WLP833 yeast up once for an expected cell count of approximately 150 billion. Too low for ten gallons of beer fermenting in the low 50's.

Label your beer - it's the law!

I left this sad sweet dunkel to age with the other beers with the idea that I would deal with it when I returned. When I say deal with it I mean dump it. But, once back here in Santa Cruz it dawned on me that there may be another solution. What if I introduced some bacteria and wild yeast to consume the remainder of the sugars and at the same time create a sort of mock Flanders brown style of beer. I checked with a few trusty homebrewers who although had no personal experience with a scheme like this, still thought it seemed like a reasonable idea. I then shot an email over to Mike at The Mad Fermentationist for advice, someone I've come to respect regarding sour beers and more importantly brewing outside the box. He wrote back regarding my question about what I could expect from re-pitching:

All strains of Brett can deal with chains at least 9 glucose molecules long, so it will certainly dry the beer out given time. Lacto/Pedio are much more variable, but with the queuze dregs something should sour it. Should be good, I've gotten stone fruit aromatics from my few lager fermented sours. New Belgium uses a lager primary for all of their sours.
Good luck! I look forward to reading about your results.
-Mike

With this new encouragement I prepared two different doses of yeast/bacteria, one dose for each Corney keg. The first received a smack pack of Wyeast Rosealare blend and the other the dregs from a bottle of gueuze that I stepped up twice. I kept the kegs at room temperature while I waited for a build up of Co2 to let me know that fermentation was going on. After a few weeks, nothing. I continued to wait, becoming concerned with the inactivity. All of a sudden after six weeks the gravities started to drop and I was venting co2 from the kegs often. It took awhile to get going but when it did, the gravity in both kegs began to go down quickly dropping from 1.026 down to 1.014 in a matter of a couple of weeks.

Dunkel With Bugs

I pulled off a sample and the flavors are good and unique for each keg and I expect the gravity to continue to drop a couple more points before I force carbonate and refrigerate. While writing this I'm sampling the beer with the Roeselare blend and it has a prominent vinegar acidity from acetobactor that plays well with the caramel maltiness from the Munich malt in the grain bill. After that comes tart/sour cherry and green cantaloupe finally ending with mild barn like qualities of brettanomyces. Tasty, thirst quenching and very drinkable. I'm happy and excited with the way this experiment turned out and would recommend it as an option for certain beers that stall out during primary.

Here's the recipe (10gal.) and statistics:
Mash at 158f (?) for 60 minutes 4 lbs. 2-row, 16 lbs. Munich 35, 10 oz. carafa II
Boil 60 minutes with 9/10th oz. Galaxy 12% and 20 min. with 1 oz. cascade 5% (24 IBU's)
Pitch WLP833 stepped up yeast culture
Eff. 90%
O.G. 1.058
F.G. 1.026 Attenuation * 55% (*after re-pitch F.G. 1.014 Attenuation 76% as of 6/6/12)

Finally, I took the opportunity to bottle some of this beer while it was still losing gravity points. My expectation is that as the beer continues to ferment I will achieve some nice natural carbonation and conditioning in the bottle without having to add additional sugar. I borrowed my friend Mark C's corker to get the job done. This is a great machine for corking Belgian style ales and wine. I've included a short video HERE to show the proper use while I bottled my Flanders Oud Dunkelbruin. Cheers!

Oh! Let's not forget that I'm right in the middle of my Kickstarter campaign to raise money to start a Beer School. Please contribute as much and as often as you can. Tell your rich friends, it's a good cause.