Cask Conditioned Brewing


By Steve Parkes (Brewing Techniques)


A Speidel Pressure Cask


Modern Approaches to Cask-Conditioned Brewing - Lessons from Britain


When the Campaign for Real Ale resuscitated the market for cask-conditioned ales in the United Kingdom, many brewers had to make significant adjustments to their brewing processes. As real ale becomes increasingly popular in the United States American brewers are well served to take note of the lessons learned by our fellow brewers across the sea.



British brewers have a great many advantages over their American counterparts when it comes to producing and selling cask-conditioned beer. Customers in Britain appreciate it, bartenders understand it, distributors know how to handle it, and brewers are devoted to perfecting it. And now, thanks to the work of an organization called the Campaign for Real Ale (better known as CAMRA), Britain’s dying style of brewing has been resurrected.

CAMRA coined the term real ale to describe ale brewed from traditional ingredients, matured by secondary fermentation in the container from which it is dispensed, and served without the use of extraneous carbon dioxide. When CAMRA came into existence in the changing beverage market of the 1970s, modern modes of thinking pervaded the brewing process. Financial issues such as product consistency, product stability, loss prevention, and the expansion of retail outlets threatened to reduce the venerable art of brewing to mass-produced keg beers served “American style.” The traditional pub with its landlord and landlady living above the bar, personally taking care of the beer, and deriving a reputation based on their beer-tending prowess, was on the wane, and modern, profit-based businesses were taking its place. Instead of underground cellars to keep live beer year-round at the perfect 55 °F (13 °C) temperature, these new pubs kept their beer warm in a corner of the kitchen and ran it through an under-bar flash-chilling unit on the way to the tap. Instead of beautiful, long-handled beer engines with sensuously shaped porcelain handles and shiny brass taps, their beers were identified only by a lighted cowl on the bar that designated which bland, pasteurized, fizzy, weak beer was being poured. They inspired no buzz in the community that their “London Pride” was particularly good this week. Instead, their business increased when word went round that the payoff on the slot machine was set higher this week or that they had some good songs on the jukebox.

Then CAMRA stepped in, and over the course of the next 10 years its efforts to preserve tradition and choice in Britain’s brewing circles turned the British brewing scene around. Old styles were resurrected, and new beers were born. By the mid-1980s, every brewery in the country was once again producing cask-conditioned ale in some form or another to keep up with consumer demand. Cask ale sales increased to 10% of all beer sales. The new, modern pubs with their space in the kitchen, their refrigerated dispense lines, their plywood bar tops, and their trendy jukeboxes needed to sell real ale too, just to survive.


Modern Solutions to Traditional Challenges


To make the transition from cold, carbonated, filtered beer back to real ale under today’s economic conditions, brewers and publicans have compromised on the use of some traditional techniques.

Malts: Cask-conditioned beer does not “benefit” from filtration; instead, brewers add finings (isinglass) to cause yeast to settle out naturally in the belly of the cask. The source of most hazes (other than yeast) is the malt, particularly malt protein. Brewers of cask-conditioned ales must have barley varieties that are low in protein and well-modified to produce beers that will clarify easily with the aid only of kettle coagulants and auxiliary fining agents.

Dry-hopping: Brewers used to add whole hops to the beer at racking to impart a dry-hop character that changed over time. Once consistency became a major issue, most brewers abandoned dry-hopping, although a few brewers still do it. Additionally, adding whole hops to beer can be problematic when it comes time to clean the casks back at the brewery. Hop leaves can stick inside casks, potentially contaminating future batches and causing serious problems with the brewery’s drains and effluent stream. Some brewers instead add hops by way of a hop back; others add hop oils or extracts to the finished beer.

Fermentation: Fermentation was traditionally carried out in open fermentors, and yeast was collected by skimming it off the top of the brew at the appropriate time. The beer was then cooled to 50 °F (10 °C) and left to mature for 3–4 days before it was racked into casks. Although many British brewers are still using their traditional fermentation systems, many large breweries must now learn to ferment cask-conditioned beers in their cylindroconical vessels, which means that some brewers will have to choose either to wait for the yeast count to fall into the correct range or to rough-filter the beer and then add back measured amounts of healthy yeast.

Racking: The increased demand for consistent, stable beer, whether cask-conditioned or not, has brought about an increased concern for how beer is filled into casks. Care is taken to monitor yeast counts, priming rates, and residual extracts. Several UK brewers add a small quantity of priming sugar to the cask to ensure adequate carbonation. (The technique of kräusening, that is, adding some actively fermenting wort as a priming agent, is not practiced in the United Kingdom). Other brewers add a preservative at this point. All additions are carefully tested for optimal performance.

Casks versus kegs: Traditional wooden casks have, for the most part, been replaced by stainless casks or enamel-lined aluminum casks. To conserve floor space in the brewery and the pub, some breweries have adopted a cask siphon, consisting of a long tube and valve that allows the cask to be stood on end. The tube, or spear, is gradually lowered into the cask as the beer clears. The siphon also allows venting, and the procedure often allows the beer to be served sooner than otherwise possible because the beer will clarify from the top down.

Conditioning in the brewery: In the past, the publican had an important role in beer maturation. With its year-round cool temperature, the pub’s cellar was an ideal place to continue the beer’s flavor generation. But when so many modern pubs have begun storing beer under less than ideal conditions, brewers themselves have taken on the role of ensuring correct maturation before dispatch. This has required that brewers create new facilities for conditioning and extend the beers’ storage period. Storing beer is a financial burden on breweries, which may have to pay tax on the beer before the pub has paid them for it. Currently, some larger breweries store the racked beer in temperature-controlled conditions until the carbonation is correct and the flavor is fully developed. This can take from 3 to 10 days after racking, so the beer may be as much as two weeks old by the time it is shipped.


A Sampling of Cask Methods from U.S. Brewers

Middle Ages Brewing Co.

Syracuse, New York

Brewers: Marc and Mary Rubenstein

Middle Ages brews 14 beers throughout the year and casks 11 of them. Cask ales account for 5% of their total sales. They use stainless firkins and sell 65 casks a month to the trade.

“We really try to do it the British way,” brewer Marc Rubenstein says. For one thing, Middle Ages uses open fermentation. After fermenting, the beer is conditioned at 45–48 °F (7–9 °C) so that the yeast count drops to 100,000 cells/mL. Then the beer is casked. Alginex (Savilles Clarification, Aldridge, West Midlands, UK) and isinglass are added for fining in the cask. Some of the beers are dry-hopped with a handful of whole hops in each cask — a source of serendipitous variation, because Rubenstein and his assistant have different sized hands. The casks are conditioned at 50–54 °F (10–12 °C) before shipment to pubs. The length of the conditioning period depends on the beer’s gravity. A 1.045 beer might condition for 10 days, whereas a 1.080 Scottish ale might condition for 10 months, but the average is 1 month.

The pub must agree to supply a cooler for the firkin. Rubenstein recommends that his pubs use cask breathers, which blanket the beer in carbon dioxide to prevent it from oxidizing as the cask empties. The cask breather extends the shelf life of the beer to 7–8 days. “I have three or four places that do not use cask breathers, but they can go through a cask in 2–3 days.”

By working closely with pubs, Rubenstein is able to safeguard the reputation of his beers. “If someone wants to start serving my cask beer, they really have to beg,” he says. “I go and feel them out and see if they really have a passion to do it.” He makes sure that the pub really has the facilities and knowledge to serve cask beers. “It’s important that my beer is served correctly. Shelf life is short, and temperature is so important.”

Back Bay Brewing Company

Boston, Massachusetts

Brewer: Tod Mott

Tod Mott’s version of cask conditioning happens partly in the unitank and partly in a serving tank. “I do my second fermentation in my unitank,” he says. “We do a three-day primary fermentation and cap off (close the tank so carbon dioxide can’t escape) at 1 °P above terminal gravity. The beer sits at 38 °F (3 °C) for 7 or 8 days, then is transferred to the serving tank.”

The beer is fined in-line on the way to the serving tank. The brewers mix up finings in a pressurized Cornelius keg and add the finings to the beer through a T-fitting in the line from the unitank to the serving tank. Mott uses this method because he purges the serving tank with carbon dioxide before filling it, and the finings would tend to congeal at the bottom without clarifying the beer if they were added in the tank.

Hops are then added to the serving tank, and the beer is held at 52–56 °F (11–13 °C) under a 2–3 psi blanket of carbon dioxide. The serving tank holds only half the contents of the unitank, so the remainder of the beer stays in the unitank, conditioning further, until the first serving tankful is empty (about two weeks).

Back Bay always has Boylston Bitter on cask, and the brewery produces other cask ales seasonally. Although the brewery’s product typically is served on the premises, Mott has casked Boylston Bitter for shipment to festivals, including the 1997 Great British Beer Festival, where it met with an enthusiastic reception. (The brewery’s Freedom Trail IPA went to the 1998 festival.) Mott acknowledges that his methods are considered nontraditional. “But,” he says, “we’re in America.”

Wynkoop Brewery

Denver, Colorado

Brewer: Kyle Carstens

Kyle Carstens has developed a system incorporating the benefits of cask conditioning while avoiding the inconsistency that can result from a true secondary fermentation.

“We’re not really priming our beers at all,” Carstens explains. “We do a single fermentation and fine it with gelatin and isinglass finings on the 38 °F (3 °C) side of our cooler; then we’ll put it on the warm side (44–48 °F [7–9 °C]). We put 2–3 lb pressure of carbon dioxide on the tank, just enough to keep oxygen from getting to the beer. Then we serve it directly from the tank through hand pumps. The service makes all the difference in the world. It goes through a sparkler (a perforated plate that forces carbon dioxide out of solution), giving it a nice head and nice lace.”

The brewpub serves about 5 bbl of bitter, 7–10 bbl of IPA, and 7–8 bbl of stout in a week. “We do things pretty basic here, and as close to old England as we’d like to get,” Carstens says. “We do dry-hop our beers and we age the IPA on oak.” But with the high volume Wynkoop sells, consistency is an issue. “It’s difficult to hit your carbonation right. There’s more chance of infecting the beer, and there are clarity problems.”

“A lot of people are going crazy with the CAMRA thing, and I appreciate the nostalgia,” says Carstens. “But if the brewers of yesterday had had the technology of today, they would have used it.”

Wynkoop’s cask ale sales have increased 30–40% during the past six years. Fewer brewpub customers object to “warm, flat” beer. “A lot more people are catching on to why it’s that way. We try to explain that this is an authentic way to serve beer,” he says.

Yards Brewing Company

Philadelphia, Pennsylvania

Brewer: Tom Kehoe

Brewmaster Tom Kehoe has adapted the cask-conditioning process to make real ale accessible to pubs and taverns that have regular draft systems. “For our flagship product, Yards ESA (Extra Special Ale), we use a single-step infusion mash, open fermentors, a top-cropping ale yeast, and finings for clarification,” he explains. “Where we differ from tradition is in the racking: We put the ale in a keg rather than a cask. Oh, horror! A keg is nothing more than a cask with a standardized, modern tapping system. Conditioning takes place in the keg. We put hops in the keg, but to keep them from clogging the lines we tie them in a sack. Carbonation is done by a secondary fermentation in the keg. For a keg this requires a higher priming rate than a cask so the beer can be dispensed through the normal draft dispensing systems. Thus, a bar can dispense a real cask-conditioned ale with all the changing characteristics and appeal of traditional cask ales.”

Kehoe makes no apologies for his approach. “When cask ales were in their heyday, there was only crude microbiology going on in the brewery. Today technology has shown a more efficient way to nurture cask ales as a live product, and the old way may not be the best way. It is unfortunate that CAMRA does not accept technology such as filtration and even kegs for dispensing, practices that increase consistency and product stability.”

“Microbreweries are still fighting the battle to educate the server and the customer about the style and profile of the product that they produce,” Kehoe says. “Bringing that one step further and introducing a product like cask ale that requires the publican to care for the product on premise is an even greater challenge. Once there is an educated house (management and server), they can serve warm, flat beer to the customer with a different perspective. The education of a few will lead to the education of many.”


Fining: Without the benefit of filtration to clarify the beer, brewers have had to learn to optimize the rate of fining to ensure consistently clear beer in the trade. Beers that do not drop bright are unmarketable to a critical public, and storage conditions are often not conducive to beer clarification. (Temperature shifts can be disastrous; overcooling can create chill haze, and overheating beyond 68–70 °F [20–21 °C] will denature the finings.) Though finings of some sort have been in use for quite some time, a great deal of research has been done in an attempt to understand how isinglass and other finings actually work. Suppliers have also perfected new blends of finings to suit particular yeast strains and that are more effective under the range of conditions likely to be encountered in the trade.

Distribution: Cask-conditioned beer was once a distinctly local phenomenon. Brewers have an old saying that their products should never be distributed farther than a horse can walk to and from in a day. Either some brewers in England own some incredible horses these days or something has changed. As available local retail accounts become harder and harder to find, brewers are having to go farther afield to sell their beers. As some beers have become national brands, the need to ensure consistent flavor and clarity under a variety of conditions has become increasingly important.

Some of the solutions to this problem, such as extended conditioning periods at the brewery, have already been discussed. Concerns with distribution also relate to issues of fining. For instance, beer fined with isinglass will only reclarify disturbed sediment 4–5 times before it can no longer work; therefore, if the beer is moved too many times, it will not settle. Distribution by a second party will almost inevitably result in more product movement and problems with clarity. U.S. brewers deal with this problem less often because their cask ales are mostly brewed and served on the same premises.

Dispense: The biggest changes affecting cask-conditioned beers have come in the area of dispense mechanisms.

Taps. New hand pumps and gravity taps with sparkler attachments have changed the way beers are being poured. The “Northern pour” (a tight, creamy head with relatively flat beer underneath, produced by a sparkler or swan neck) is now fairly common throughout Britain, replacing the “Southern pour” (no head but fizzier beer). Some pubs even have hand pumps that incorporate both methods of pouring into the same mechanism.

Temperature. Temperature can now be better controlled by a number of innovations, including foot-shaped probes for the inside of the cask and jackets and coils for the outside.

Cask breathers. Most importantly, the development of the cask breather has extended the drinking life of many a cask by excluding harmful air from the finished product without adding extraneous carbon dioxide. Maintaining proper condition (carbon dioxide content) in the cask has always been a problem requiring careful cellarmanship. When beer is removed from a cask, carbon dioxide tends to come out of solution to fill the void, flattening the beer. The traditional porous spile allows oxygen to contact the remaining beer, resulting in oxidation over time. Cask breathers, introduced about 20 years ago, allow carbon dioxide to flow into the cask at the same rate that beer is removed, creating a carbon dioxide blanket over the beer and preventing oxygen contact with the beer underneath. Another alternative is keeping the cask under low carbon dioxide pressure (0.25–0.5 psi). CAMRA accepts breathers, but if the beer is to be consumed quickly (say, within 2–3 days), breathers are probably not necessary.


Real Ale in the New World


Fortunately, the research and developments that helped English brewers improve the consistency and overall performance of their cask beers will help American brewers in their attempts to authentically reproduce beers in this traditional manner. American brewers needn’t get hung up on tradition, of course (it is unusual to find just the right conditions to produce, market, and serve cask-conditioned beer even in England), but the fight to preserve cask-conditioned ales has breathed new life into Britain’s brewing scene and certainly has a place in the United States’ growing craft brewing market. So, if a horse named English Drayhorse shows up in the Kentucky Derby, bet your mortgage on it.

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