Souring a Belgian Strong Dark Ale

Question

I brewed something last fall with friends, and the recipe was somewhat off-the-cuff. I wasn't super happy with the results. We were aiming for a Belgian Tripel, but weren't careful in selecting our grains and ended up with something between a Triple and a Quad. It is a bit more malt-forward than a Tripel, but not as dark as most of the Quads I have had. It also had a pound or more of Belgian candy sugar which left quite a bit of residual sweetness despite finishing at about 12% ABV.

I don't really like the end result, and the beer has been kegged in my fridge for about the last 10 months. The beer doesn't really have any off-flavors, I just don't care for the combination of sweetness and maltiness. I'm considering trying to sour the beer with lactobacillus or doing an additional fermentation with brett. I love sour beers, and was thinking this might be a good opportunity to salvage this beer and turn it into something I'm excited about. If it turns out undrinkable I won't be heart-broken.

Does anyone have any suggestions for me? I'm not sure what strain of bugs to use, and for how long, and whether I will need to add fruit or something to provide additional food for another fermentation. I'm assuming this will affect the alcohol content as well, but I'm not sure to what extent.

Thanks!

Answer 1

The two you will want to use are either Wyeast 3763 Roeselare blend, or WLP655 Belgian Sour mix. If you want to get real squirrely, follow the Mad Fermentationist's lead and go grab a (fresh) bottle or two of your favorite sours from the store, smoothly pour out all but the last half inch of the bottle, swirl the dregs settled at the bottom of the bottle, and pitch those in.

Now before you go and do this, there's a couple of things to keep in mind. The little critters provided by Wyeast and WLP (rumored to be the same yeast strain) will tolerate up to 11% ABV. You have 12%. This is going to be a problem. The brettanomyces which is in the pack/vial is a bit more tolerant, but the Lacto and Pedio may be overwhelmed. Brett won't sour your beer alone, but it'll give it a huge farmhouse apple funk. You certainly could try to pitch a vial or two, toss in some (pasteurized) oak, and see how it looks after a year of aging, but don't be too surprised if you don't get the sour character you were hoping for. If you go this route, try and purge your carboy with CO2 to get all the oxygen out of the head space. By next year when it will hopefully sour, it'll be two years old, and while it's certainly high enough ABV to last two years, oxygen will only degrade the final outcome.

Finally, unless you want to add fruit, you probably shouldn't. I'd suspect that if it's a year old, the yeast is probably not healthy enough to fully ferment out the sugars, so that's all the more work the Brett is going to have to do, and it's already going to be stressed by the immense ABV.