This article originally appeared in the July/August 2010 issue of The New Brewer.

La Método Solera –Traditional methods for the production of unique beers

By Will Meyers, Brewmaster, Cambridge Brewing Company

“Hey, Phil, I’ve got a great idea!”  So began a journey which continues today in all of its rewarding, sometimes frustrating, but ultimately drinkable manner. I was speaking to Phil “Brewdaddy” Bannatyne, founder of the Cambridge Brewing Company (CBC), where I brew. The year was 2004, and I had just gotten off the phone with my friend Carl Sutton, owner and winemaker of Sutton Cellars. We had received some wine barrels and lees for various barrel-aging experiments from Carl, who is heavily influenced by Spanish winemaking traditions despite his location in California’s Sonoma County. Our subsequent conversation was about Carl’s visits to the sherry producing region around Jerez, Spain, and how I had the idea to craft a beer which was produced through the same system as sherries, known as soleras.  For better or for worse, Phil gave the project the thumbs-up and we proceeded down a now seven-year-long path.

A solera is essentially a number of casks which contain an identical liquid of consecutive ages.  In the case of sherry, a quantity of the wine is drawn off at intervals throughout the year, and the cask refreshed with slightly younger wine of the same style.  The younger wine will gradually take on the character of the older wine, and after several months the wine in the cask becomes virtually indistinguishable from what it was before.  A dynamic system of maturation is developed whereby wine is constantly transferred through a system of barrels containing wines of increasing age. Each stage is called a scale, and includes the solera – the oldest barrel or set of barrels – and the criadera, literally the nursery, which is made up of a series of barrels of successively younger vintages. The term solera denotes both the entire system as well as the oldest set of barrels.  In Marsala wine production, the system goes by the name perpetuum, and a similar program is in place for the production of banyuls, maury, muscatel, and some port wines, as well as brandy and rum, balsamic and sherry vinegar, and even whiskies.

Our project started with a beer we’d begun producing called Cerise Cassée, a beer initially produced via a sour mash of 100% of the grist in order to produce an acidic beer without the required extended aging time and danger of contamination from lactic acid-producing organisms. One fifth of the original batch served at CBC was racked into a French oak wine barrel and inoculated with B.bruxellensis, just for kicks, and after several months we determined that this beer had a complexity which surpassed the original in a very pleasant way. It was this beer which would form the foundation of our project.  A full batch of Cerise Cassée was brewed and racked to a set of four newly procured, neutral French oak red wine barrels, plus the original Brett-inoculated barrel from Sutton Cellars, which to this day is named “Carl.” A liter or so from the original beer aged in Carl was added as inoculant to each of the other four barrels. One year later, 30% of each barrel was racked out and blended to be served and another batch of the same beer was brewed. The head space was topped up with the new batch, and the remainder went into a new set of five barrels set atop the originals. Our solera and criadera were in place!

The word solera derives from the Latin solum or the Spanish suelo, meaning ground, floor, or earth according to Julian Jeffs in his comprehensive book on sherry.  While this system of wine production has likely been common knowledge amongst winemakers since the earliest days, the terms solera and criadera first appear in an inventory of the sherry house of Garvey in 1849 (though they were probably in use much earlier). Amazingly, two of the criaderas of amontillado sherry mentioned in that inventory are still working today.  Even more incredible is a two hundred year old cask of beer, still maintained in Sweden, of an old Walloon ale. Old ale was brought to Sweden by Walloons who emigrated to develop the burgeoning iron and steel industry. Their tradition of brewing, today closely resembling Flemish Red ales and Old Bruin, was to age a beer in oak casks, drawing off as much as half of the beer every one to two years and refreshing the barrels with new beer or wort. After aging in oak the pH drops, thanks to resident flora, and ultimately produces a tart brown ale with considerable winelike character.  The single remaining barrel of an 1806 set from the Bayerska Bryggeriet in Sweden is privately owned and still maintained by the same family since 1860!

Other beers known to be produced in solera-like systems include Gale’s Prize Old Ale, which according to Ron Pattinson (his blog, Shut Up About Barclay Perkins, should be required reading) was fermented at Gales in unlined wooden fermenters, then shipped to the Fullers Chiswick brewery and aged for two years.  At bottling, forty barrels were left in the maturation tank and the next batch racked atop to maintain the Gales character. Greene King’s Strong Suffolk Ale was once similarly a blend of young-into-old ale, though I was not able to ascertain specifics of production and it may now be more simply a fresh beer with a smaller portion of aged, sour beer added before pasteurization. The famous Ballantine’s Brewery is reported to have produced their incomparable Burton Ale in a system whereby IPA was aged for several years in mammet-lined wooden tanks with additional dryhopping, and each year after a small portion was bottled off the tanks would be topped back up. Representing the current Italian brewing revolution, Teo Musso of Birreria Baladin in Piozzo crafts a beer which bears the influence of metodo solera. Called Xyauyu, it is produced in three versions – Gold, Silver, and Copper labels - which differ in terms of degree of oxidation and character due to differing amounts of time in the tank and barrel. It is exceptionally vinous and sweet, similar to a vintage port or aged wine from Marsala. And I would be remiss in failing to mention the Danish Norrebro Bryghus, where I was involved as guest brewer in the creation of their beer Stevns CCC with then-Brewmaster and founder Anders Kissmeyer. After the inaugural batch, the beer was subsequently brewed by Kissmeyer and Shaun E. Hill, now of Hill Farmstead Brewery in Vermont, who guided it into a multi-barrel solera of its own.

On the American craft brewing front, New Belgium Brewing Co. in Fort Collins, CO, has been an innovator in terms of barrel aging thanks to a project overseen by Lauren Salazar, QA Director, and Brewmaster, Peter Bouckeart. Their initial forays into “wild” beer production evolved from individual barrels to massive oak foeders. Bouckeart, previously Brewmaster at Belgium’s Rodenbach, has had considerable experience with extended aging and blending of wood-aged beers, and it was Lauren who had much earlier first impressed upon me the idea of never completely emptying a barrel, in order to maintain the integrity of the resident flora. New beer or wort added to replace beer that was drawn off would provide a constant level of sugars and nutrients to maintain the culture. New Belgium’s iconic ale, La Folie, was one of the first beers of this type produced by an American craft brewery.

On the East Coast, Delaware’s Dogfish Head Brewery makes waves with its exotic Paraguayan wood-aged Palo Santo Marron, and Dogfish Head Brewmaster Floris Delée is developing a framework for continued production of this beer. Delée writes, “The challenge that we face with Palo is that nobody has used a similar wood before and we experience over time, while aging Palo, that this really cool beer is becoming more and more complex, mainly favorable. However, we also need to map this aging and release and bottle our Palo when it is best. The Solera technique allows us to explore and capture the peaks (what we like and are excited about) and valleys (what we have to live with but also learn from) in this rich flavor development of the aging Palo. At the same time it allows us to bring more Palo barrels into the system with their specific permeable wood conditions. Second, Palo has a relatively high alcohol content compared to the oak aged beers as Rodenbach Vintage or Marriage Parfait from my fellow countrymen - it leans closer to Manzanilla van La Guito from Spain for example. I believe the higher alcohol content is an advantage here. Third and last, I believe that by never truly emptying the barrels we allow a microbiological micro cosmos that helps us deal with some of the less favorable aspects of the wood.”

Not all soleras need to be produced through massive oak tanks or dozens of barrels. Freetail Brewing Company’s Scott Metzger and his team are producing solera-style beers in single barrel batches at their brewery in San Antonio, Texas. While their beer, Solera, is relatively new, they are using a bourbon barrel filled with their flagship Freetail Ale and pull a half barrel of beer from the wood each month for service. “We really like the idea of single-barrel soleras as we can isolate time as the sole variable in the changes to the beer,” says Metzger. “It’s also nice because it helps maximize the limited space we have to devote to barrel aging.”

Since the craft brewing industry grew directly from homebrewing, it is worth mentioning that much of the information on soleras, like many innovations in American brewing, has been well-plumbed by our homebrewing brethren. Jeff Renner published an article on his solera-influenced homebrewing project in Zymurgy magazine in 2002.  He describes his system of annually blending barleywine or Scotch ale into a single Cornelius keg containing previous versions of strong ale. Originally meant to beef up a bland beer, he found he enjoyed the perpetual supply of increasingly more mature beer as the years passed. In online forums, homebrewers regularly post about their solera systems, using carboys, kegs, or barrels. The Blogosphere also bears several champions of solera-style beers, notably homebrewers Michael Tonsmeire of The Mad Fermentationist and Nathan Zeender of Desjardin Brewing  in the mid-Atlantic. Both bloggers regularly update their exploits in fermentation, and they teamed up to brew and fill a sixty gallon wine barrel over two brewdays with a lambic-style ale, and plan to rack out fifteen gallons annually to yield a beer with an eventual average age of three years. The two have even created a convenient spreadsheet for calculating the average age of a beer (or any liquid) aged in a solera system. Solera Spreadsheet Many homebrewing clubs have adopted this method, allowing many brewers to contribute wort or beer to a group barrel, and bottling off proportionately to their contributions.

It is important to note the difference between beers which are aged separately and then simply blended with younger beers, and those which pass through this cascading system of vessels. The distinction is that in a true solera, the finished product is meant to consistently come only from the oldest set of barrels, and these are constantly replenished by the next oldest regardless of the ultimate number of scales in the system. In working the scales of a solera, the brewer seeks to maintain as even a distribution as possible when topping up each older level. Therefore, if thirty percent of a barrel is emptied, an equal amount from each barrel in the next scale is drawn out to total the volume removed from the older barrel. If this is not done, significant variations can occur in the development of the individual casks. The solera system has been scientifically investigated and mathematicllay analyzed, and obviously a solera consisting of many scales requires a significant amount of effort to maintain!

Frustration comes from not only investing countless hours in support of this system, but also when realizing the limitations of a system like this in the CBC Barrel Cellar, which has notoriously low ceilings and creates a situation where barrels, once stacked in place, are nearly impossible to move. My biggest mistake was in placing the criadera barrels directly atop the solera, which is problematic as we have recently decided to remove some solera barrels for cleaning due to heavy sedimentation and some notes of autolysis in the beer. This now requires a dramatic and complicated series of racking out of and then back into barrels from several scales in order to rearrange the system for ease of use in the future. Each of these barrels at CBC must now be hand-carried upstairs for cleaning and then carried down again to return it to the cellar. Interestingly, according to Jeffs the belief that in Jerez the scales of a solera are mounted one on top of another is an erroneous notion. Also, when utilizing barrels housing many strains of microflora it is important to note that the porosity of the oak staves will diminish over time, and can affect the natural cycles of mixed fermentations, so our recommendation is to avoid the literal “stacking and cascading” interpretation of the solera and instead spread out the scales as much as possible for ease of exchange if necessary.

The CBC Solera has undergone some changes over the years, but consistently results in an annual release of about eight hectoliters of Cerise Cassée from the solera level of our system. Proportional blending has become the norm, as certain barrels have expressed a propensity for producing higher acid concentrations than others, or result in a more attenuated beer, and a balanced and consistent beer is the goal every year. Whimsy has also played a part, as over time we have sometimes added sour cherries to the beer during primary fermentation, other times directly to the barrels to spark a stronger secondary fermentation. While an essentially spontaneous fermentation takes place thanks to the organisms residing in the barrels, over the years we have also on occasion added various mixed cultures (from the dregs of some of our favorite beers) to the odd barrel here or there. Ultimately it should be noted that the solera is never refreshed with beer less than one year old, and this year’s release of Cerise Cassée contains a blend of beer aged up to seven years.

Despite the effort required in perpetuating such an intensive system, the results are worthwhile and unique. Applicable to a wide range of beers, from sour ales to barleywines and old ales and strong lagers, a solera system enables the consistent creation of complex beers with significant aged characteristics otherwise unattainable to most small production craft brewers. At CBC we also feel it is a tremendous learning experience, as it teaches us to be attuned to a greater extended lifecycle in brewing than that afforded by our regular production beers.

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i Jeffs, Julian. Sherry. London: Mitchell Beazley, 2004. 212. Print.
ii Pattinson, Ron. “Fullers Griffin Brewery.” Shut up about Barclay Perkins. Oct.-Nov. 2008. Web. 11 May 2010.