Let me start off by thanking you all for contributing to this website. I've been lurking about as long as I've been brewing (15 months) and I wouldn't have even known where to start if it wasn't for you guys (and gals)!
Now, let's get down to business. In November, I brewed a Vanilla Porter for the holidays. Brew day went smoothly, but in my typical fashion, I didn't plan far enough ahead for the beer to properly condition and carbonate before Thanksgiving. I think it only spent 10-14 days in primary. So, as one could imagine, the beer was pretty green at Thanksgiving. By Christmas, it was mediocre, but still a bit "sharp" tasting. Anyways, after the holidays I emptied the remnants of the keg into a growler (only half-full) and stuck it in the back of my fridge.
Fast-forward about 6 months. Today I was cleaning out the fridge and lo and behold, I stumble upon the forgotten growler. I almost dumped it down the drain, assuming that it would be oxidized to high hell after spending 6 months in a half-empty growler, but then curiosity got the best of me. I twisted the cap and was surprised to hear a hearty "psssssssst." It didn't smell funky and there wasn't any sign of a pellicle, so I filled up a New Holland Brewing Company pint glass. It turns out the brew was still slightly carbonated! Now for the moment of truth. I took a sip and wouldn't you know it, but the it actually tasted better than when I put it in the growler. All of the sharpness had mellowed out into a smooth, velvety mouthfeel and finish. Most interestingly, the vanilla flavor had subsided to the point that it pretty closely resembled the vanillin notes that result from cask conditioning!
So, for a Porter, I've (accidentally) discovered that vanilla + extended aging is a pretty decent approximation to cask conditioning. I assume this trick would work for other dark beers too, but I'm not positive. Does anyone want to weigh in on this?
p.s. Here's the recipe:
5 gal. batch
OG = 1.053
Broke hydrometer immediately before measuring FG
Estimated FG = 1.015
5 lbs Breiss Golden Light DME
1 lb Caramel 120
12 oz Dark Brown Sugar
8 oz Chocolate Malt
4 oz Munich Malt
2 oz Roasted Barley
8.25 AAU Willamette @ 60 minutes
5.4 AAU EKG @ 10 minutes
Wyeast 1028 (London Ale)
1.4 fluid oz Vanilla Extract in secondary (turned out to be a little too much)