Firkin awesome

Next to the usual CO2-pressed lines, tap beers touted as "on nitro" or "on cask" are a mainstay of your cookie-cutter West Coast brewpub. But how often do you get to sit down and do a three-way horizontal tasting of the same brew poured each way? Plus all the firkin jokes you can handle? How could we resist? The folks at CAMRA would certainly've been proud.
Sidenote: While the term "firkin" simply denotes a specifically sized keg (9.5 US gallons), its use in contemporary brewing circles connotes a beer being matured and pulled from the same cask via a beer engine, thanks mostly to a chain of brewpubs in England bearing the name. The brewing world is full of great terms (wort! bung!) but etymological Valhalla is reserved for the ones that look like misspelled curse words .
The test subject was the newly-minted pale ale "Shining Star" from our local brewpub. They describe it as "crisp" and "well-rounded", which is fairly accurate (if not a little vague) in terms of a West Coast style. The Iron Springs proprietary yeast strain exhibits more distinctively British characteristics (less hop accentuating, rounder malt flavor) than a California ale yeast would, but the beer is still dominated by Cascade hops in all its faithful, grapefruity bitterness in both nose and finish.
The CO2 version was unremarkable, but a good baseline for anyone who's ordered a pale ale in a brewpub in Northern California. Giggly preconceptions aside, however, the batch matured and served in the firkin was quite interesting. While it wouldn't have won any beauty contests, it certainly delivered the most complex character of the bunch and went down like any true session ale you'd ever want to find. What really surprised me, though, was the nitro version. Whereas I had visions of creamy, Boddingtons-like sweetness, it was the exact opposite. With the finer bead of the nitrogen unable to clean the resin off the palate, the balance was totally unhinged by the hops, pushing the sticky, piney, less respectable facets of the Cascade to the fore. All in all, an interesting test, but the cask ale easily outshined the others. Of course, a 9.5 gallon keg in a 100-seat pub doesn't last that long either, making it all that more precious in comparison to the daily fare.
Some of the results of letting a beer go through its conditioning phase in the same container that it's dispensed from were to be expected - a hazy appearance and a hint of yeast bite from the lack of filtration. Even your run-of-the-mill homebrew is racked off the sediment once it's completed its residency in the carboy as a final act of clarification. And unlike delicately decanted ale-on-lees, firkin ales are pulled forcefully by a hand-drawn piston, which not only stirs it up a bit, but accounts for a portion of the creamy mouthfeel in what is otherwise a very lightly (and naturally) carbonated libation. What surprised me was how the character was even rounder, more floral, and complex than I'd expected. Granted, the warmer temperature (55º F!) that it was served at might have contributed to the perceived complexity, considering the nitro and CO2 versions were considerably colder.
While the Shining Star is no longer on cask (we got the dregs, yum!), you can always find "real ales" at the Magnolia Pub & Brewery, or you can just go and brew your own. And if any of this sparks your interest, just think: only 11 months until the 3rd annual firkin festival at Triple Rock!