Here we are, it's finally time to put my 12% Imperial Stout down for a nice long twelve month nap. To quickly recap, I'm brewing a huge imperial stout, and trying my best to mimic the barrel aging process for the beer. I've been wanting to brew a beer like this for a quite a long time, so it feels really good to finally get moving with it. I'll skip over most of the barrel aging process, as I covered that in my last post.
For this recipe, I borrowed heavily from my prior Imperial Stout. I felt that beer turned out really nicely, so I wanted to carry over as much as I could. The main goal here was just to amp up the gravity to the 1.120-1.125 range to finish out around 12-13% ABV. To get there, I'm adding a couple pounds of 2-row, and I'm cheating with a couple pounds of DME. My efficiency starts to fall off a cliff around 1.100, so using DME for a beer like this becomes really attractive. Considering it's such a small percentage, and I really don't want to boil this beer for 3-4 hours, DME it is. Lastly, I added another quarter ounce of Apollo to get another 5IBU or so. Everything else with the recipe is the same.
The next step was charring 1oz of oak cubes. I got my propane torch, some water, and headed into the garage. I torched the cubes on one to two sides until they turned bright orange, and then doused them out with water. Those went into a few ounces of Maker's Mark for three weeks before they were strained and dropped into the beer. You can see the difference in the color of the two bourbons in the picture at the top. One is Maker's Mark straight out of the bottle, and the other is Maker's after 3 weeks of soaking.
The brew day for this beer was interesting. Any time you cram something like 27lbs of grain into a 5 gallon batch it always is. I started off by getting a huge starter of WLP090 going. I don't tend to worry too much getting 9-10% beers to the finish line, but 12-13% without using exotic yeast can be tough. I used 2 vials in a 5L starter for this one. As for the brew day, it was fun. I mashed for 60 minutes as usual. I also added a little extra water to the sparge volume for efficiency's sake, since this was a 120min boil. The first runnings of the beer were 21 Plato, and my gravity after the 2 hour boil was 27.75 Plato. This was a little under my target of 28-28.5, but I'm not too stressed about it. Next year, I'll boil the batch for another 30minutes, I had extra wort left over. I skipped the whirlpool for this one, and started chilling right away. It's always interesting just how much thicker wort like this is than a normal gravity beer. Anyway, after chilling to 60F, I hit the beer with a solid three minutes of oxygen before pitching the yeast.
Despite rigging up a blow off tube, I'm always surprised by how much yeast blows off of an Imperial Stout. I lost about a half gallon of wort, but I think something like 25% of the yeast must have blown off. Things really slowed down after 3 days, and at 5 days the gravity was still chilling at 1.048. After ten days I was still at 1.033. It took almost a full three weeks to hit a final gravity of 1.026. My only theory on what took so long is that the massive blow-off resulted in a large loss of healthy yeast, and maybe that slowed down the race to the finish. I'm not entirely sure. Either way, the beer tastes really great at this point, and the final gravity was in the range I was looking for.
.75oz Apollo @ 15
1oz Medium Plus American Oak Cubes - Charred, and soaked in Bourbon
And that's about where this story ends for now. I just got done racking the 12.1% stout into a keg, and tossed the oak cubes in a day later. My plan is to purge the pressure valve on the keg once every month or two to let in a tiny bit of O2 into the keg, and see where that gets me. The goal is to sit on this beer for close to 12 months so that it's ready to go for Christmas 2016. I can say that the base beer turned out pretty fantastic for being flat and quite young. Unfortunately, we'll have to wait a full year to get any conclusive results on how this little experiment went. Since time tends to be the hardest variable to quickly replace, I've already charred another 1oz of oak cubes, and I have them soaking in bourbon. If things go well with this year's batch, the oak cubes will be ready to rock for next years batch.
Anyway, cheers for now, and Happy New Year!