Why Cask Ale?
In a word, flavor. Cask ale has flavors that standard keg beer does not because it is served at a different temperature, has lower carbonation levels, and is continually worked on by living yeast interacting with the changing conditions inside the service vessel. When done right, there is nothing so thirst quenching and satisfying as a pint of proper pulled with practiced care. This experience has inspired such fervent devotion that in the United Kingdom there is a Campaign for Real Ale, CAMRA, that is fanatical in the defense of this ideal.
“Brewed as cold as the Rockies” is a familiar tag line for a representative of American macro-lagers. While undeniably refreshing and incredibly technical to make, this style of beer is served cold so that your taste buds are numbed to the point where they do a poor job recognizing the flavor of the beverage being consumed. This is to disguise the fact that the beverage itself doesn’t actually have much flavor. Brewing to exacting standards with a minimum of cost-effective ingredients is bound to have an impact on flavor and, if the emphasis is shifted to refreshment via strong marketing campaigns, that flavor can take a back seat.
At warmer temperatures taste receptors are better able to discern flavors that would be lost in the same beverage served at frosty temperatures. Malt flavors come to the fore as aromatic compounds are released. A perception of the thickness or gravity of the beer begins to fill the mouth, giving the beer a “mouthfeel”. This continues as temperature rises to a degree before the beer begins to lose that refreshing quality. Too close to room temperature and the beer isn’t very refreshing. Too cold and it isn’t very flavorful. That happy medium is called cellar temperature , which is 48 – 54°F.
Cellar temperature itself is a storied term. Legend will have you believe that it is that consistent temperature of a dug earthen cellar when you get about six to ten feet below grade. The practical reality of it was that refrigeration as we know it did not exist before 1834. It didn’t become commonplace until much later, perhaps as late as the first World War. Subterranean storage, when it did exist, made for a good place to store the local brewery’s wares. It is undeniable that the temperature in a cellar is more consistent and cooler than the above-ground area. A consistent cooler temperature is better for perishable goods such as beer.
The way cask ale is prepared and served also has an effect on flavor. The most obvious point is the lower carbonation levels of cask ale. It is less fizzy. This is apparent in both smell and taste. In the nostril, there is significantly less burning sensation due to gaseous CO2 converting to carbonic acid on your mucal membranes. This same acid is also reduced in solution so the beer has a bit less “bite” than the same at standard levels of carbonation. This also has some subtle impacts on the way the chemistry of flavors in the beer evolved while it was packaged.
With less fizz comes less in the way of prevalent aromatics. Those aromatics are still there (and more abundantly, given the warmer temperature as discussed above), but they are no longer being lifted off the beer by the escaping CO2. They stay closer to the surface of the beer and influence the experience of richer beer flavor as they are detected as the beer is being consumed.
The traditional service method for cask ale is to breach the vessel above the beer and allow air in to replace the volume of beer dispensed. This exposure to air introduces not only spoilage organisms but also atmospheric oxygen. The latter of these is typically more relevant as any spoilage organisms introduced lack the time to develop to the point where they are a detriment to the flavor. Usually a spoiled beer can be traced back to bacterial loading at the brewery!
Oxygen is a highly reactive gas that is available for a large number of chemical reactions. It can have a staling effect on beer flavor (wet cardboard) and a mellowing effect on harsh alcohols. The geometry of the vessel with its single small port at the top and the relatively undisturbed airspace above a beer slowly off-gassing CO2 causes these reactions to happen slowly. It is terrifically informative to try the same beer over several days of service to fully appreciate the oxidative effect of a maturing beer. The flavor changes over time!
Cask ale is an option for beer service. Some beers are simply better on draught or in bottles. Two examples are Imperial IPAs (the carbonation lift really favors the onslaught of hop aromatics) and lambics (the thinner body helps compensate for the far greater acidity of the style). This is not a polemic to convince you that cask ale is the only way to enjoy your beer. The fact that the styles that do best on cask happen to be the more interesting styles to consume is an exercise left to the reader.
Defining Cask Ale
Let’s differentiate between cask ale and real ale. Real ale is any beer (ale or lager, despite the name) that has undergone a secondary fermentation in a sealed vessel. Because the vessel is sealed, the carbon dioxide (CO2) produced by the yeast, and only the yeast, is trapped and has nowhere to go but into solution. This carbonates the beer, giving it condition. The terms carbonation and condition will be used interchangeably in this text.
There are a variety of vessels that real ale can be conditioned in. Since the late 1500s, bottles have been the vessel of choice for highly carbonated beer. That’s right – homebrewed beer is real ale when it is bottle conditioned! Before that, wooden casks or ceramic crocks were used. Due to these vessels being unable to hold significant condition, the beer carbonated in them tended towards much lower maximums. As you can read in the sidebar to the right, there has long been debate about the role of carbonation in beer. In the modern age we can use pressure-rated stainless steel vessels. So long as the yeast is the sole source of the CO2, you are making real ale.
Cask ale is real ale served from a vessel with separate gas inlet and liquid outlets. Some common ones include the English casks for which this style is named but also includes German gravity kegs, Cornelius-style kegs common in home-brewing, stainless steel 5L mini-kegs, and even Sanke kegs.
The one exception I’m familiar with is from David Line’s classic Big Book of Brewing where UK homebrewers were encouraged to make real ale in a collapsible water container. One could serve perfectly conditioned real ale from such a container by doing the secondary fermentation while the serving spout was positioned on the top of the container, venting the excess CO2 at the appropriate time, then gently rotating the container into serving orientation and allowing the container to collapse as pints were pulled. This is essentially what KeyKeg or KeyCask allows one to do, but I digress.
This definition of cask ale focuses on the source of the CO2 and does not require service from the vessel in which the secondary fermentation occurred, nor does it require the introduction of atmospheric oxygen. For these reasons, it fails the CAMRA definition of cask ale. This is perfectly fine. CAMRA should hold the line and stick with the historic definition of cask ale. Our modern times allow for additional strategies to get the benefits of cask ale while avoiding some of the pitfalls in order to get more cask ale done well to the drinking public.This allows for such strategies as: all of the German cask ales, rack-bright beer, blanketed service, and a host of other strategies that we’ll get to in due time.