The Menuism blog has a post that covers the basics of a cask-conditioned ale pretty well, and it is definitely worth a read if you are not familiar with beer served from a cask, or as the Brits call it “real ale.”
Basically, regular kegged beer is carbonated and dispensed by using pressurized CO2 in a two-stage process. First, the beer is force carbonated inside the kegs using high-pressure CO2. The beer is then shipped to the customer who dispenses the beer through their taps using lower pressure CO2 to push the beer out of the keg, through the lines, and out of the tap faucet. Cask beer does not use any external CO2 for carbonation or serving. The beer, which unlike kegged beer is unfiltered, is stored in a small metal or wood cask or firkin with some additional sugar added. The yeast that is still in suspension in the beer eats this new sugar and naturally carbonates the beer. The ale is then served at “cellar temperature,” or close to 60F, with a hand-pump called a beer engine. The server literally pulls the beer (hence, “pulling a pint”) out of the cask and through the lines with the pump.
The result is a living pint of lightly carbonated beer with a thick, creamy head, and a mouthfeel that needs to be experienced. Additional flavorings can be added during the conditioning period, and anything from coffee beans to more hops are commonly used. The type of sugar used for the carbonation can also impact the flavors of the beer subtly.
There is more to cask beer, and the menuism post covers much of the additional information. If you still are intrigued by the concept you can read about all of the tradition that surrounds cask beer on the British site for The Campaign for Real Ale (CAMRA); an organization dedicated to preserving this historic method of serving and enjoying our favorite beverage.
There are a few spots in Los Angeles that serve cask ale. The Pub at Golden Road (Facebook) taps casks on Tuesday-Thursday and occasionally on the weekend, and both Blue Palms Brewhouse and Mohawk Bend regularly have beers available on cask. And beer festivals are a great place to try cask ales; watch our weekly Tapped Out feature for details. Have you tried cask ale? Let’s hear your thoughts in the comments.