Lambic: The Pinnacle of Natural and Native Brewing

If the concept of terroir can be applied to beer, it would be with the spontaneously fermented, wild lambics. Lambic is inoculated by airborne microbes of the landscape and banked within barrels. They are the pinnacle of natural, native, organic brewing—a cascade of countless transformations that separate them from the rest of the beer world.

True lambic is produced only in Brussels and Senne River Valley (the Pajottenland-Zennevallei) in Flemish Brabant. Its brewers adhere to a royal decree drafted in 1965 that states it must contain at least 30 percent unmalted local wheat, ferment spontaneously, use aged hops (surannés) and be brewed in Brussels or within 15 kilometers. Lambic that is brewed to these strictures are labeled as “oude,” a confirmation of traditional methods. Lambics are unfiltered, desert-dry and can be archived for years.

The name lambic has enigmatic and equivocal etymology. It may refer to the Zennevallei town of Lembeek (Flemish) or Lembecq (French), derived from alembic, a type of distilling apparatus, or lambere, Latin meaning “to sip.” 

Few beers travel such an intriguing and transitive journey from birth to maturity. Every turn is unorthodox; attention to venerable methodology and a close rapport with nature are essential. Lambic is not only a type of beer itself, but also serves as the base for blended lambic, or gueuze; fruited lambic; and sweetened faro. Brewing is only done in cool months, and age is measured in summers.

Lambic begins with roughly 1/3 local unmalted wheat and 2/3 pale barley malt. The grist is mixed with warm water, then a portion of the murky wort drawn immediately, boiled and returned to the main mash. This drain/boil/return cycle is repeated until the mash is sufficiently converted. This prolonged schedule takes the mash stepwise through critical enzymatic temperature points and dismantles components into simpler microbe-friendly compounds.

The boil lasts from three to six hours, greatly concentrating the wort, promoting further breakdown of starches and proteins and deepening the color from straw gold to light amber. Aged hops, devoid of flavor or aroma but effective antiseptic agents, are added during the boil.

Post boil, hot wort is sent to coolships (koelschips)—shallow, open basins in the upper reaches of the brewery—and cooled overnight. Windows are opened and the wort is ambushed by the native mosaic of microflora wafting in from the surrounding countryside. The drafts also circulate microbes from the interior building structure, perhaps centuries in the accumulating.

After overnight cooling, the teeming wort is drained into wooden barrels that serve the dual purpose of fermentation and aging. The barrels themselves are a virtual microbiological reservoir, the tiny grottoes on their inner surfaces home to invisible magicians from batches past. The barrels are oak or chestnut wood, formerly used for wine. They range in size from 250 to 9,000 liters.

The wort then succumbs to yeast and bacteria, some 100 strains strong, opportunistically pouncing as conditions, such as pH and residual or metabolic byproducts, successively favor one over the other. All leave their own unique calling card, and they work symbiotically. The workhorses are several Saccharomyces and Brettanomyces yeast strains, as well as bacteria such as Enterobacter, Lactobacillus and Acetobacter.

The fermentation and aging last several months to several years, depending on the fate of the lambic.

Saccharomyces strains provide “normal” fermentation and attenuation. Acetobacter (vinegar bacteria) strains then use ethanol from primary fermentation as their nutrient. After a few months, lactic-acid bacteria, Pediococcus and Lactobacillus get their chance to sour the lambic. Finally, Brettanomyces lambicus and bruxellensis (named for the beer and the city, respectively) toil during maturation, furnishing the coveted musty character, working alongside oxidative strains.

The base straight lambics are generally reserved for cafés around Brussels and can be casked, bottled, young (jonge) or old (vieux). Cantillon is one exception, as it exports Grand Cru, a straight, unblended lambic.

Some lambic producers purchase cooled inoculated wort from other breweries and ferment, age and blend it themselves. These “blenderies” are known as geuzestekerij, or gueuze blenders. They distinguish themselves by house conditions, barrel type and the skill of the blender. De Cam, Oud Beersel, Tilquin and Hanssens are geuzestekerij, while Boon, Lindemans and Girardin are wort producers and blenders.

Gueuze is blended lambic generally consisting of three different summers. Each batch of lambic is unique, and the blending of gueuze is the work of a skilled artisan known as a steker (blender). Sometimes more vintages are used for the desired character. Jonge lambic provides lively effervescence and energy, the vieux lambic lends its fully aged, mature character, and the middle-aged lambic rounds things out. Usually, jonge lambic makes up the majority and vieux the minority.

For fruit versions, one-summer lambic is racked into a barrel containing fruit, kickstarting a secondary fermentation. The most common fruit lambics are cherry (kriek), raspberry (framboise), black currant (cassis) and peach (pêche). Kriek is made with sour Schaerbeek cherries, a stellar sweet-sour complement to the vast tapestry that is lambic. Faro is blended lambic sweetened with dark candi sugar, filtered and pasteurized. It is a darker, sweet, bright version of lambic.

Lambic breweries are beer preserves, wild and woolly, but kept under control by their keepers. Lambics have never been more popular, and have spawned a broad corollary brewing movement in North America of wild, sour and barreled brews. There is nothing, though, quite like the originals, the finest work of Old World artisans, brewing as nature intended. 

The following beers were tasted by K. Florian Klemp.