The quest of beer-lovers leaves virtually no cellar undisturbed. That pursuit is often about the novel inspired by the venerable, with the current curiosity in sour, aged beers motivated in great part by Flanders red and brown beers. These brews are an alliance of ordinary top-fermentation, supplemented by unconventional organisms, finely sculpted by aging and blending. They borrow much from neighboring brewing practices and ingredients, mingling those to create something quintessentially Belgian and uniquely Flemish. These complex specialties are some of the most refreshing and remarkable brews in the world. Belgium itself is a melting pot, something reflected in their brewing attitude. Its brewers are wryly mindful of the big picture, but coyly ambivalent to their opinion.
The northern half of Belgium, Flanders, has been a cultural potpourri for the past few centuries. Historically there is an intimate physical and philosophical connection with Germany, France, The Netherlands and Britain, all of which contribute to many great beers of Belgium. The sour red and brown ales of Flanders may be the finest manifestation of that adoptive and adaptive mentality. The modern brewers of these closely related, nearly identical styles, retain sufficient traditional design to ensure a bond with that most rustic of all beers, and neighbor, lambic. They employ many of the same bugs as lambic, but without true spontaneous fermentation. In essence, these could be considered more modern versions of the archetypal white and red ales of Belgium, with controlled inoculation and fermentation. Lambic is a remnant of white (wheat) beers, and Flanders ales red (barley) beers of Middle Ages Europe. The understanding of microbiology has certainly aided brewing in many ways, and just as we appreciate the wildness of lambic, so do we admire the stylistic bravado of Flanders red and brown that this technology has kept alive.
Just a few scant centuries ago, all beers were either spontaneously fermented or spiked with slurry from a previous batch. That slurry could have contained any number of wild yeasts and assorted bacteria adapted to the region. The porosity of wooden fermenters and storage vessels would also have harbored a population ready to invade the fermenting and aging beer. In a nutshell, Flanders red and brown ales harken to those days, when terroir and primitive techniques ruled brewing world. Today though, design, rather than serendipity, drives these artisans.
Over time, brewers learned to control brewing, selecting purer strains, and learning about controlled fermentation schedules and seasonal cycles. In parts of Germany especially, bottom-fermentation and cool storage was becoming the norm some 500 years ago. But British, Belgian, Bohemian and Northern German brewers were still making top-fermented beers, mostly at the mercy of the season, often sour or musty, or both. Patient aging became de rigueur in Belgium and Britain, where aged and young beer was blended. In Britain, “stale” was not only the name of the aged stock ale, but also described its desirable tart and horsey notes. Much of this came from lengthy aging in wooden casks, from several months to several years. Oak (particularly French) was and still is the preferred cask material, being abundant, easy to work with and sturdy, while bestowing its own personality to the aging beer. Vanillin and tannin are the two most recognizable nuances imparted naturally by oak. It is also quite porous, providing microscopic grottos for persuasive organisms, and a permeable membrane, allowing oxygen, a nutrient for Brettanomyces and Acetobacter, to contact the beer. Only used wine casks are employed in the making of Flanders beers. New oak is overpowering, but aging brings almost magical distinction to the wood. Older oak looses some of its woody character, but becomes more hospitable to microorganisms. Coopers are as important for their barrel building and maintenance skill as are the brewers. The barrels are scraped regularly to remove pore-clogging material, and are periodically disassembled and reassembled. Rodenbach, the grandfather of the West Flanders red style, has many casks over 100 years old, and some that date to 1868. Wood aging makes for convenient sampling and hence, blending, during the process, an important aspect of brewing in the 18th and 19th centuries. The British were especially known for this then, and the Belgians still for some styles, Flanders ale and lambic among them. There was much brewing cross-pollination between the two countries during that era. The common Brettanomyces (British fungus) brewing strains were actually isolated from casks used to age British stock ales in the 19th century.
Though the Flanders styles are considered anachronistic, its brewers have modernized over the past few decades while retaining respectful attachment to heritage. Spontaneous fermentation has been replaced by mixed culture inoculation. Coolships, the large, shallow open fermenters that offer the best surface area for spontaneous fermentation, have mostly been replaced. Rodenbach introduces Saccharomyces cerevisiae, Lactobacillus delbrueckii and Pediococcus parvulus to their wort, allegedly culled from their old coolships. S. cerevisiae takes care of the initial ordinary fermentation of sugars during primary fermentation, with L. delbrueckii and P. parvulus taking their successive turns during secondary fermentation to produce souring, lactic products. Tertiary fermentation is done in their famous oaken barrels (foeders), where several Brettanomyces species finish the job, a duration of 18 months to 3 years. The voracious Brettanomyces is capable of fermenting sugars, including dextrine, which Saccharomyces cannot, resulting in ultra-high attenuation. This lengthy maturation and multi-organism fermentation coupled with the oaky nuances is, in the end, sublime. When mature, Rodenbach blends its young and old beer in two main products for bottling. The regular Rodenbach is three-fourths young and one-fourth aged beer, while the more assertive Gran Cru is two-thirds aged and one-third young beer. The aging beer, known as “foederbier,” can be sampled at selected times in its unblended, pristine condition.
The East Flanders brown, or oud bruin (old brown) style, is famously produced by Leifmans in Oudenaarde. The brand is known as Goudenband. The main difference between it and Flnders red resides mainly in the method of fermentation. All necessary organisms, Saccharomyces, Pediococcus and Lactobacillus strains, are added to the wort prior to fermentation. It is said that this mixed culture originated at Rodenbach. The primary fermentation is done in open squares, where some airborne wild organisms may alight, and lasts about one week. When the wort reaches about 75 percent attenuation, it is transferred to stainless-steel tanks and the secondary organisms, Lactobacillus and Pediococcus, take over. Brettanomyces is absent from the mix, as is oak obviously, a condition reflected in the finished beer. The result is less attenuation and a bit less fermentative complexity, but this is more than made up for with more robust contribution from malt. Goudenband is hopped a bit higher, giving it a more classic ale profile.
The grist composition between the two sibling styles varies from brewery to brewery, but all use continental malts, at home in top- and bottom-fermented brews alike. Rodenbach has a base of Vienna malt, with crystal and deep brown Special B for dextrine, flavor and color. Liefmans prefers pilsner malt and Caramelized Vienna and Munich malt for color and sweetness. Other brewers use variations on that template. A measure of 10 to 20 percent flaked maize is common to lighten body and aid lactic fermentation. Red emerges with a brisk fresh fruity character of cherry and plum, and brown with notes of dried dark fruit, toffee and caramel. The less famous versions of the two styles can come very close to one another in character, further proof that stylistic separation is sometimes futile. Regional conditions and a common pool of ingredients make it even more so.
The rather rare and highly unusual ales of Flanders are without a doubt an acquired taste, but in this era of experimentation and exploration, they are not without many devotees. Sour ales in general are becoming more and more popular, and even in America some adventurous brewers are toying with these wild and wooly organisms in a fashion that would flatter Flanders. If you haven’t tried them yet, take a taste on the wild side.