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What's Old...Is New Again By Jim Anderson
First of all, the terminology.
A cask is like a keg, only smaller (about 12 US gallons), and with a different design. This design allows for a special tap and a venting system which allows the cask to breath while the beer is being poured.
Beer normally does all its fermenting at the brewery. In some cases (as with many Belgian and French beers that come in 750ml bottles) a second fermentation occurs in the bottle. This is called "bottle conditioning", and is evidenced by a layer of yeast on the bottom of the bottle. When that second fermentation occurs in the cask, it's called cask conditioning, and the layer of yeast collects in the bottom of the cask. This second fermentation in the serving vessel allows a brewery to release a fuller-flavored "live" beer that does not have to be filtered or pasteurized.
Normally, draft beer is dispensed by forcing CO2 into the keg and pushing it up through the draft lines. This method not only adds carbonation to the beer, but also protects the beer remaining in the keg from spoiling. Since casks are not designed for a CO2 line, the beer must be dispensed by gravity -- simply pouring it directly out of the cask (which is sometimes perched right on the bar) -- or by a hand pump, which acts just like an old-fashioned water pump -- as you pump, beer is sucked up through the beer line and out the spout. In both gravity and hand pump dispensing, the displaced beer in the cask is replaced by air, which will break down the beer quicker than CO2 will in a conventional keg. Because the beer is undergoing a second fermentation as it's being poured, it creates its own carbonation.
Pasteurization is a process which keeps perishable liquids from spoiling quickly. It can be done by several methods, the most common of which in the beer business is to pass a filled keg or bottle through a hot water bath to kill any microorganisms that might remain in the beer. An unpasteurized beer is "live", containing living microorganisms such as yeast. The alcohol in beer will kill any harmful bacteria, which is why unpasteurized beer is not the health risk that unpasteurized milk is. The second problem with cask-conditioned ale is the special care it requires in order to be served at optimum flavor.
Cask-conditioned ale has a very short shelf life (two weeks if the cask is kept sealed; about five days once it's been tapped), which means if you can't turn the product over quickly, you'll end up selling bad beer.
Casks require a special stand (stillage), as well as airflow regulators (spiles) and special taps. If you are considering selling cask-conditioned ale, look to your distributor or brewery to supply this stuff. You'll also need a handpump to pour the beer (about $350), unless you want to give up a customer seat and pour it by gravity from right on top of the bar.
There is hope, however, for the more timid. Several breweries are trying to offer the public the flavor of cask-conditioned ale without the hassle. Brewery-conditioned ales and keg-conditioned ales are not as sensitive to temperature or handling as their cask-conditioned cousins, and can be driven through your normal draft system without any special equipment. While these products don't have the purist appeal and yeasty softness to their palate, they're a substantial improvement over normal keg beer, and enjoy a longer shelf life. Locally, look for excellent keg- or brewery-conditioned ales from Yards, Stoudt's and Dock St. Brewery & Restaurant. All these products come in a variety of styles, most commonly Pale Ale, Stout, Porter, and India Pale Ale.
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