Lambic: Belgium's Unique Treasure


by Martin Lodahl (Brewing Techniques)




Lambic: Belgium’s Unique Treasure


But is it really beer?” The first taste of a lambic is almost always a surprise — sometimes even shocking — especially to those whose concept of beer is defined by North American industrial lagers. Where’s the malt? And the hops? Why is the mouthfeel so dry? I have always enjoyed introducing people to lambics, watching their eyes open in astonishment at the first taste. The surprise is to be expected — lambics are the product of an altogether different brewing tradition, one that varies strikingly from the Pasteur-inspired methods used by virtually all of today’s breweries. Yes, it’s really beer, but…


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Lambics Defined


First, let’s be completely clear about what lambics are and are not. Lambics are made with wheat, but only a few wheat beers are lambics. A few lambics are made with fruit, but using fruit in a beer doesn’t make it a lambic. Adding to the confusion, commercial brewers have produced beers they call lambics but that have, in fact, nothing to do with the legal definition of a lambic.

Yes, legal definition. Unlike most beer styles, lambics have laws that define them. Readers of this column know that beer is taken very seriously in Belgium. Lambics are perhaps the most traditional of the myriad Belgian styles, so it should come as no surprise to learn that in Belgium lambics are defined both by royal and ministerial decrees. The first defines lambics as beers brewed from a grist of at least 30% unmalted wheat and spontaneously fermented. The second reaffirms (in case anyone missed the point) that they are the product of spontaneous fermentation, then goes on to define that fermentation as one that results from the action of “yeasts and characteristic bacteria indispensable to the success of processes of fermentation,” which specifically are carried in the air. The ministerial decree expressly forbids pitching with pure cultures or fermenting beer.

Spontaneous fermentations: When I first read about lambics, I was sure this description couldn’t be right. Modern brewing technique leaves as little to chance as possible, and one of the keys to consistency is eliminating or minimizing the chance of infection by airborne yeast. Could it be that a whole family of beer styles really depends on apparently random infections, and could those beers possibly taste anything other than awful?

My first taste of gueuze, in a cafe in Paris, convinced me that if beer that good could be made using a pitching technique like this, then something truly unique was happening here. These products of spontaneous fermentation are not in any way disgusting, as you’d expect infected beer to be. The best examples have an intense refinement and a beguiling complexity that place them among the finest of any beverage. The worst are merely insipid.


Lambic History - From Time's Distant Past


Origins: I have heard and read a number of intriguing theories concerning the origins of the term “lambic,” but the one I tend to believe holds that the name is taken from the village of Lembeek in Payottenland, the heart of the lambic production region, itself named for the nearby creek flowing through chalky hills on its way to the river Senne. The village of Lembeek was once a major hub in the commerce in beer of this type, and for centuries these beers have been made in the region. The lambic production area includes the west side of Brussels and the suburbs and surrounding countryside, never more than 20 miles from the spectacular Gran Place.

Lambic beers seem to have changed little since Pieter Brueghel the Elder (1525?–1569) painted lively pictures of the region’s Flemish peasants. Michael Jackson has suggested that the russet-colored liquid being poured from one stoneware vessel to another by a figure on the extreme left of “The Wedding Feast” may in fact be a lambic, an identification far more believable than the assertion found in some art history texts that it is wine. Payottenland is simply not wine country, and the people in the painting are grain farmers. What’s more, a lambic ordered in a rural cafe today will often be served in a stoneware vessel strikingly similar to those in the painting.

In Brueghel’s day, spontaneous fermentation was not so unusual. Most worts were pitched with a quantity of fermenting beer from a previous batch, and airborne microorganisms and the biota living in the barrels and fermenting vessels became part of the biological stew conducting the fermentation. Fermentations were not entirely random, however; brewers found many ways of guiding the progress of the fermentation, even if they weren’t in primary control of the organisms involved.

In the 19th century, the brewing traditions of the rest of the world were profoundly influenced by the works of Pasteur and the experiments of Emil Hanssen and others. Belgium, however, held tenaciously to its traditional methods and styles and continued to rely on spontaneous fermentation for many beer styles. Of those styles, though, it was clearly the lambic beers, principally faro, that was first in the estimation of most Belgians. By 1900, some 3000 lambic breweries dotted the tiny production area, not much larger than Brussels itself.

Foreign beers: Foreign influences, however, began to make inroads into Belgian drinking habits as early as 1840, when a few barrels of English beer appeared in a cafe in Brussels. By 1850, several specialty cafes were serving English beers, and Bavarian beers had begun to arrive. At first, lambic drinkers felt these new beers were just a passing fancy that would never challenge the supremacy lambic beers enjoyed.

Because of their tawny color, these beers were called “browns” by lambic brewers, a subtle and derisive comparison with the first batch or two a lambic brewer would produce upon reopening the brewery each September — beer intended more for cleaning out the equipment and seasoning new barrels than for consumption. Quicklime would be added to the water, which would darken the color of the beer substantially, and the beer was sometimes used in small quantities as a coloring agent to make over-aged beers seem younger than they actually were. Because these beers were also referred to as “browns,” the implication was that the non-lambic imports were not “real” beer and were actually unsuitable for consumption.

Almost from the beginning, though, lambic enthusiasts waged a losing battle. Belgian drinkers were long accustomed to a specific price range for lambic beers, and consumers were considerably resistant to paying more. The new beers, however, were a novelty, and because they were imported, drinkers had little objection to paying the higher prices. For retailers, that meant higher profit margins. The number selling “brown” beers in Brussels increased from 6 in 1865 to all 8099 in 1885. Between 1869 and 1885, some 25 breweries were built in Brussels to brew these new beers. Lambic’s long decline had begun and would continue through most of the 20th century.

World War II dealt a bitter blow to the country’s many small family-owned breweries when the copper brewing vessels were confiscated during the Occupation for use in making munitions. During the postwar years, lambics, which are naturally quite sharp and acidic, found themselves on the wrong side of the shift in public taste toward less assertive flavors. The extremely high cost of producing lambic beers forced prices upward as well, just at a time when many sophisticates were dismissing lambic as a “farmer’s beer.”

When extinction seemed inevitable and the number of producers had fallen to a tiny handful, natural and traditional products returned to favor in the late 1960s and 1970s, bringing a reassessment of Belgium beers. Michael Jackson, however, deserves the credit for their remarkable surge in popularity outside of Belgium in recent years. In books, articles, and television appearances, he has made millions of beer lovers aware of these remarkable beers, which in turn has created a demand that some lambic producers still find astonishing.


Meet the Family


Lambics young and old: Lambic begins with a single basic wort, but by the time it is served it can be one of many different substyles, each with a range of possible characteristics. There is such a thing as “straight” lambic, or lambic from a single cask, sold either when it is young (called vos or foxy lambic) or old (vieux lambic) — relative terms, of course, as any lambic that has aged through only one summer is considered young.

Straight lambics are highly variable products; they are frequently sold straight from the cask at specialty cafes and continue to change from day to day. Both vos and vieux lambics tend to be quite sour, and many cafes serve them with a few lumps of (usually dark) sugar so they can be sweetened to taste. This practice has its roots in antiquity when lambics were somewhat more sour then they are today. While the lactic acid content of today’s lambics ranges from less than 2000 ppm to more than 5000 ppm, lambics analyzed in 1839 and 1871 were in the vicinity of 11,000 ppm both years. Although the analytical methods of the day make it possible that these figures could be measuring acetic acid as well, these figures are still considerably higher than the combined acids of modern lambics. The flavor characteristics of these two acids are dramatically different from each other, so not only is the total amount of acids important, but also the balance between them.

The 20th century has seen a substantial consumer preference for very mild levels of both acids, but interest now appears to be a growing in the more assertive products, with both “hard” and “soft” products winning their partisans. In a soft lambic, there may be a substantial presence of lactic acid, but acetic acid levels don’t stray too far from the flavor threshold. Producers and blenders of lambics of this type look for subtlety and balance in their products; examples include the Hanssen’s line, the Boon line, and Lindemans’ Cuvée Rene Geuze. A hard lambic, with acetic acid levels that are sometimes very high, is a far more assertive product, even aggressive. Its wildness can make sampling it a delightfully invigorating and sometimes challenging experience. Cantillon products tend to be hard. It is inevitable that the production process will produce some barrels of beer that are harder than others, but producers try to guide the course of the fermentation so as to make the final blend representative of the “house quality” they work very hard to maintain.

Of the two most common types of unblended lambics, the vos lambic seems to be the more extreme of the two — the result, I suspect, of its relative simplicity of flavor. It is usually cloudy, with very little carbonation. The vieux lambic has much more interesting flavors, frequently featuring the rural earthiness that is the calling card of Brettanomyces yeast and an accompanying wide range of esters. These lambics are usually dead flat, and I have met one or two that were “ropy.” Ropy beers take a little getting used to. They are characterized by a certain viscosity, in some cases in the form of filaments that you can actually draw from the beer. In others, it takes the form of a gelatinous mass, similar to a vinegar “mother.” In my own experiments, I have seen ropiness develop and then spontaneously disappear.

Gueuze: To my palate, the finest of beverages is this blend of old and young lambics, refermented in the bottle in a way that is frequently compared to the Méthode Champenoise. The process of making gueuze lacks the remuage and dégorgement of the true Méthode Champenoise, though, so I can’t help feeling that the local joke about gueuze being produced by a “Méthode Bruxelloise” is actually more to the point.

Gueuze is bottled in very strong champagne-style bottles (complete with punt), which are corked, then capped, and stacked on their sides to mature through at least one summer. Because the blend often contains as much as 70% young beer, carbonation can be considerable. In fact, during a heat wave in the summer of 1931, more than 3 million bottles of gueuze burst.

As is frequently the case in the lambic world, every producer has a distinct idea of what a gueuze should be and blends the beers carefully to achieve it. For reasons that will soon become clear, blending is the highest art of the lambic producer, and the characteristics of the blend are nowhere more important than in gueuze.

By the way, this article uses the French spelling of the name, which is the most commonly used in English-speaking countries; the Flemish spelling, “geuze,” is the preferred spelling in its native land. Creation of the style has been attributed to many different places and times ranging from 1870 to 1893. Several stories make a connection between an early producer in the style and a liberal political party, the Geus.

As mentioned above, each producer has an independent concept of the style, so someone who has only tasted the delicate fruitiness of Mort Subite, for example, might be a little surprised by the extreme sweet fruitiness of St. Louis or shocked by the intense lactic and acetic sourness of Cantillon with its successive waves of delightfully assertive complexity. Very traditional gueuzes like Cantillon, Boon, or Hanssen tend to be emphatically dry and complex. High percentages of aged beer in the blend and long bottle fermentations produce very complete attenuations, showing off the fermentation effects to best advantage.

Not all gueuzes, however, are produced using traditional methods. Some are a blend of lambic and a less unusual top-fermented beer, bulk-fermented, filtered, and artificially carbonated. This approach was originally developed to produce a gueuze stable enough to ship to homesick colonials in the Belgian Congo, but it lives on for economic reasons. Gueuze produced in this fashion tends to be sweet, with a fuller mouth-feel and relatively little complexity. These are often very pleasing beers, but they lack the profound depth and truth of the traditional examples.

Fruit lambics: To judge from the “how do you make a lambic” questions that regularly appear in the electronic brewing discussion forums, most North Americans who are aware of lambics at all think of them as fruit beers. This comes as little surprise; fruit lambics seem to be the most readily available in North America. Here in my part of the United States (northern California), for example, it is far easier to find a framboise than to find a gueuze. The largest lambic brewery, however, reports a far different production profile, with gueuze at 48% of its annual production, kriek at 45%, and framboise a trifling 7%.

Confusing the picture further are the non-lambic beers made with the same fruits as in lambics, and known by the same names. This does not necessarily imply deception. Such designations as kriek and framboise are not defined in the way lambic or gueuze–lambic are and refer solely to the fruits used, without specifically indicating the base beer.

The two most common fruit lambics are also the two oldest. Kriek, made with cherries, dates from approximately 1930, and framboise (Framboos, Frambozen), made from raspberries, is from 1978, making it a very late arrival in the lambic world. Some of the more adventurous brewers have continued experimenting with other fruits, and one can now readily find lambic made with peaches (pêche, perzik) or black currants (cassis). Still others have been made with bananas, pineapple, and even strawberries, passion fruit, and mirabelle plums.

The method for making fruit lambics was traditionally quite straightforward, with whole fruit and lambic racked into barrels to referment for months or years, then the resulting beer lightly filtered and bottled. For a kriek, the preferred cherry is the now-rare Shaerbeek, a dark red sour cherry with a large stone and very little flesh, though many now substitute Moreno or Northern cherries.

In a 650-L (5.5-bbl) pipe, the traditional quantity was 150 kg (330 lb) of cherries and 500-L (4.25-bbI) of lambic, though many producers now use much less fruit. A loose bundle of sticks is then placed in the bunghole to keep it from becoming blocked by the pulp and stones of the fermenting cherries. When fermentation is complete, three parts of the resulting beer is mixed with one part young lambic (for priming) and bottled. A number of producers still use this method, though only few use it exclusively. Juices, syrups, and concentrates are increasingly used, as is the practice of pasteurizing before the secondary fermentation is complete, to obtain a sweet product.

Krieks. Traditional krieks are some of the world’s best-looking beers, with an astoundingly deep ruby to garnet color offset by a delicate pink head. The fruit comes through strongly in the nose, along with hints of the lambic character. The flavor is sharp and dry, with almond notes from the cherry stones. Some producers favor an intense sourness while others prefer balance and finesse, but all in this category (which includes Boon, Cantillon, and Hanssens) have a very direct real-fruit flavor and clean dryness that makes them an outstanding aperitif.

For many consumers, though, such an approach is too hard-edged, and they prefer the far sweeter and less complex krieks that dominate the market. Very much the same sort of situation is the case for framboise. In general, the lambics made with other fruits are very sweet beers, sometimes to the point of being cloying, but they often go well with fruit-based desserts.

Faro: A century ago, faro was the most popular drink in Brussels and was well-regarded all over Europe. Its enthusiasts called themselves “farocrats” and composed songs and poems to celebrate the beer. Beaudelaire, who spent two less-than-successful years in Brussels in the 1860s, was somewhat less enthusiastic and wrote, “Faro is drawn from that great latrine, the Senne. It’s a drink extracted from the excrements of the city the river divides. In that fashion, the city has been drinking its own urine for centuries”.

Described by less hostile observers as a lively drink of lightly tawny color, it was then a point-of-sale mixture of lambic and mars, a light table beer. Mars, now completely extinct, was made by doing a second mash with the spent grains of a lambic batch and fermenting it separately. The proportions of this mixture varied widely, but the fact that an equal mixture (called half-en-half) was slightly more expensive is suggestive. By the 1950s, faro had come to mean a beer made from barrels of lambic too acid to serve, blended with a much larger quantity of a light blending ale and sweetened with sugar. The few examples produced today seem to be of this description and are sometimes lightly spiced.


The Unorthodox Lambic Brewhouse


The world of lambic brewing is a very disorienting place for a conventional brewer. It is a world in which the grist contains unmalted wheat, the mash encourages the formation of starches, dextrins, and tannins, and the wort reaching the kettle is extremely thin and is boiled for several hours using an immense charge of hops aged to the point where bitterness and flavor are just a memory. The wort is then deliberately exposed to the breezes overnight, run into barrels known to contain wild yeast and bacteria, fermented, and aged for years in a cellar festooned with cobwebs. …

The grist: Let’s start with the grist, which is invariably pale, consisting of a two-row pale malt (unkilned “wind malts” are occasionally used) and an unmalted wheat. Crystal or color malts are not used. The wheat, as much as 40% of the grist, is a soft variety and often white. Sacks of wheat chaff are sometimes added to the mash to aid in lautering. A few brewers replace a fraction of the wheat with corn or rice. Typically, the wheat is milled first at 0.04 in., then the mill is reset for a gap of 0.06 in. and the malt is milled.

The mash: A variety of mashing systems are used in lambic production, but the most interesting and unique is the so-called turbid mash described in the accompanying diagrams. This system has elements in common with older Belgian mashing systems. What makes it different from other mashes in general use is the removal of a liquid mash fraction before conversion is complete. Unlike decoction mashing, which abstracts a “thick” portion of the mash, turbid mashing takes a “thin” one. From the beginning, then, enzymes are being removed from contact with the grain each time the turbid mash is extracted, and by the time the liquid is returned to the mash it has been heated to a high enough temperature to effectively denature the enzymes. The result is an extraordinarily thin wort, rich in starches and dextrins. Further, the high-temperature sparges and the additions of boiling and near-boiling mash water tend to extract tannins with unusual efficiency, producing a somewhat astringent wort.

Boiling and hop additions: Because of the thinness of the sweet wort, a boil of 5–6 h is required for the wort to reach the 10–12 °P (1.040–1.048) target. During the boil, a substantial hop charge is added (direct scaling would place it at 1.5–2 oz in a 5-gal batch), but these are not ordinary hops. Hop flavor is not desired at all in these beers, and hop astringency is scarcely more welcome. In lambic beers, the hops revert to their original role of controlling the microbiological growth in the beer, so the hops are aged for up to three years before use. Favored cultivars include Kent Golding, Fuggles, Brewer’s Gold, Northern Brewer, and the Hallertauer varieties.

The heart of lambic brewing: At the end of the long boil comes the real beginning of the story of lambic brewing. The hot wort is pumped to a shallow coolship, usually located in a louvered loft at the very top of the brewery. Coolships of this type were once a standard feature of breweries the world over and are still used in a few, though the tendency today is to enclose them in a room provided with carefully filtered air. In the case of lambics, however, the intention is actually to encourage the contamination of the wort by airborne microbiota, so the coolship is generally open and accessible to anything smaller than a pigeon. For these reasons, the production area is limited to a region of only about 10 square miles; only in that region has the ideal mix of microflora been found.

It cannot be overstated that the biological agents responsible for the unique flavors of a traditional lambic are truly the “local rot.” A stroll through the lambic production area will confirm this — that sharp, lambic tang is in the air. For this reason also lambic brewing is a distinctly seasonal occupation; in the warmer months, the microbiological climate becomes too “hot,” containing very high concentrations of organisms unfavorable to flavor development. The lambic brewing season today is typically reckoned to be from 15 October to 15 May, the dates being somewhat elastic. In the days when the demand for lambics exceeded the supply, brewers would frequently start the season earlier and end later, though the beers produced at the extremes of the season were less well regarded.

After a night in the coolship, the wort is run off the trub and into barrels. Old barrels are strongly favored over new ones, and some brewers prefer barrels that once held port wine. In recent years, the most productive source for a brewer’s barrel supply has been from the liquidation of breweries that have closed. The barrels are of a variety of sizes — the 650-L (5.5-bbl) pipe and 267-L (2.3-bbl) tonne are perhaps the most common, and the 3000-L (25.5-bbl) foudre the most impressive.

The barrels are prepared for use by washing them with hot water and steam. If they are to be stored empty, sulfur is burned in them to preserve sanitation. Because wooden barrels tend to carry microbiological agents including Brettanomyces yeast, the extent to which the barrel is cleaned can have a substantial impact on the beer it produces. A brush made of beechwood twigs called a ramon is used to scrub out the sediments, and, if desired, the barrel can be scraped clean by whirling sharpened chains inside it.

Fermentation. The barrels’ bungholes are left open during primary fermentation. They have been cut into a rectangular shape and are considerably larger than they were when the barrel was used for wine. The froth from the fermentation is permitted to slop over the sides and to harden into a porous plug over the bunghole, which gives the beer a measure of protection against oxidation but is probably a better defense against fruit flies. Fruit flies, which are known to be vectors of acetic acid bacteria, are the reason spiders are permitted to live unmolested in lambic breweries. What some visitors have taken for carelessness is actually a clever application of biological controls to influence the course of the fermentation and the nature of the final product. Later in the process, the bunghole is closed by covering it with several layers of coarse cloth held in place with a wooden billet.

The fermentation process itself is astoundingly complex. For a clear and readable investigation of the details of the process, I recommend the remarkable book Lambic, by Jean-Xavier Guinard; he in turn gives references to the primary sources. Though much research has been done in recent years, a great deal remains unknown. The summary that follows is taken from this book and from notes of a lecture by Dr. Roger Mussche (University of Leuven), presented in Seattle in 1994.

Bacteria and wild yeasts. Of the wide spectrum of organisms that land in the wort during cooling, most will be unable to tolerate the environment. The first to “gain the upper hand” are enteric bacteria, which multiply rapidly in the wort, reaching a concentration near 108 cells/mL by the end of the first week. As the pH of the beer drops, their concentration drops also, and they are gone after a month or so. The population of various types of yeast increases along with the enterics. Kloeckera apiculata (which can ferment only glucose and produces lactic acid) reaches a concentration of 105 cells/mL in the first week, secreting enzymes that break down the proteins produced by the turbid mash. These yeasts are displaced by Saccharomyces yeasts, which reach a concentration on the order of 5 X 106 after a month or so. The Saccharomyces perform the main alcoholic fermentation and drop the pH to around 4.0.

After two or three months, the concentration of lactic acid bacteria, especially Pediococcus damnosus, begins to rise. Pediococcus damnosus is one of the few hop-tolerant lactic acid bacteria and is a feared brewery contaminant. Lambic brewers are on far friendlier terms with it and prefer to call it P. cerevisiae. Lambic brewers speak of the age of their beers in terms of summers, and when the temperature rises, so does the concentration of lactic acid bacteria. In general, they are very slow-growing, with highly specific nutritional requirements, and their concentrations never grow terribly high as they slowly drop the beer pH to around 3.2. These bacteria are implicated in the development of oily or ropy mouthfeel, which in extreme cases can grow to look like the surface of a brain.

Fortunately, this ropy quality seems to disappear in the next phase, when the yeasts of the Brettanomyces genus become established. These yeasts, prized in some wines and once a common feature of stock ales and stouts, add a great deal of complexity to lambics, especially the aromas and flavors described as “horsy,” “mousy,” or “old leather.” They also produce some acetic acid and prodigious quantities of esters. When they begin to grow (about eight months into the fermentation), they form a thin film, called a pellicle, over the surface of the beer, a film which brewers go to great lengths to avoid disturbing.

Two principal Brettanomyces species can be found in lambics — urban breweries frequently show a higher concentration of B. bruxellensis, while in rural breweries B. lambicus dominates. Naturally, this has led to considerable debate, each brewer insisting that the dominant species in his own brewery is the one producing the better flavor.

These are the “high spots” of the process; by one count more than 85 organisms are involved, each with its own appropriate time and unique contribution. The microflora in each barrel will contribute somewhat differently. Some barrels inevitably sour the beer to the point where they are too acidic to be used for anything other than cleaning the equipment, but others will be usable in blends of various sorts. The art of blending is so central to lambic production that specialists have made it a practice to buy fresh wort from brewers and perform the fermentation and blending operations themselves. As Jackson has pointed out, a simple bottling in a small lambic brewery may involve a coupage of some 50 selected barrels.


A Priceless Anachronism


This has been a very general overview of the world of lambic beers. For many generations the beers and the culture supporting them lived in harmony with a small, highly specific environment, but the environment has changed a great deal, and so have the beers. The overall shift in drinking habits to “industrial” lagers greatly reduced the number of breweries and nearly eradicated the geuze-steker, blenders who buy wort from a brewer, carefully conduct the fermentations in their own barrels, and blend the result. The lambic brewing process makes extensive demands on both space and labor, both of which are costly. Survival for most of the remaining few has meant either hiding traditional lambics behind sweetening agents and fruit flavors or streamlining the process to produce a far less interesting product.

Recent years, though, have also seen a sudden surge in interest in traditional lambics on the part of people who live far from the production area. This new demand may just preserve lambics that really are lambics, keeping the tradition intact. They’ve been with us for centuries, and I personally hope they remain with us in traditional form for centuries to come.

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