In the spirit of Home-brew 101, I wanted to take a moment to discuss the differences, why they exist, and hopefully encourage fellow craft beer enthusiasts to give cask beers the reverence they deserve.
What Exactly is a Cask Beer?
Casking a beer is simply a different way of storing and then serving a beer. Rather than bottling or filling a keg with a finished beer the beer is inserted into a cask.
Uh… How is that Different From a Keg?
The devil is always in the details. When beer is kegged it is a totally finished product. The beer is filtered to remove yeast and any other sediment, it is carbonated with CO2, and when served the beer gets to your glass by CO2 being added to the keg to push the beer to your glass.
When casking a beer, the beer is intentionally unfiltered. When it is transferred to the cask (aka racked) it has freshly fermenting wort added to the cask to have the unfiltered live yeast slowly continue to ferment the beer and produce carbonation in a process called krausening.
Why Cask Condition Beer?
Well the resulting beer has a lower level of carbonation, similar to a beer on nitro. Yet the lower carbonation is not an illusion of a replacement nitrogen for carbon dioxide but a truly lower level of carbonation. This provides a nicer, smoother mouth feel when drinking cask beers. As the beer is unfiltered it generally is a bit cloudy but both the aromatics and the flavor of the beer are enhanced by the complexity of the beer plus the unfiltered yeast and possibly other sediment. It is often served warmer (at around fifty-five degrees Fahrenheit) so the more delicate complexities of flavor are more striking than a typically colder draught beers.
If Superior, Why Aren’t All Beers Casked?
The downside to storing/serving beer this way is that it makes the beer extremely perishable. Unlike kegs that push either nitrogen or CO2 into the keg to push the beer through the lines into your pint glass, cask beer is served via a hand pump system. Much like a portable keg tap, air (with the very unfriendly to beer element Oxygen) is pushed into the cask to push the beer out into your glass.
Once tapped a cask beer should be drank as quickly as possible. It is possible that within 48 hours the beer will begin to go completely flat and begin to spoil. Thus most bars prefer something with a bit more longevity as if the beer is not consumed within that timeframe it may go to waste taking the potential profits with it.
Why Should You Try Cask Beer?
There is always a danger to having cask beer as it is thee most likely way to get a sub par beer experience. Too often an inexperienced or apathetic bar might let their cask beer sit too long and serve beer that has gone flat or spoiled completely. Which of course might turn a novice or even seasoned drinker off from the style. Cask beer should never be warm, muddy, or flat. If it is any of these, demand a refund as you were served unacceptable and undrinkable beer.
However, when served properly this style of serving a beer accentuates what distinguishes the greatest elements of craft beer. Served at a warmed yet still cool temperature allows the palate to appreciate more subtle flavors that might otherwise be masked by colder temperatures. At the same time, the lower carbonation encourages the drinker to hold the beer a little longer in the mouth before swallowing, enhancing the experience of each sip. The unfiltered nature increases the smell of the beer often adding subtle notes that are not available in a non-casked counterpart. It also adds another layer of complexity to the flavor of the beer which can push a good beer into greatness.
In the end, this is a style that replies wholly on the quality of the beer brewed. With this style you cannot hide behind an overabundance of hops, the frigid cold, or filtering out errors in your beer. A true craft beer enthusiast who wants to taste a beer without anything between them and the beer’s flavor should revel in the ability to try a beer casked.
So I urge you to try a beer on cask the next time you see it as an option. Especially a beer you have had before. See if having a favorite beer on cask is suddenly like having an almost different beer. And use these facts above to convince a friend to try it as well.