At about three months, lactic acid-producing bacteria, Pediococcus and Lactobacillus, take their turn. Around eight months, Brettanomyces yeast species (bruxellensis and lambicus) grab the reins, and work for another year and a half to give the musty, barnyard character so craved by lambic devotees. Finally, oxidative species take over the final stages of fermentation/maturation, often alongside the Brett. Lambic may ferment and condition for several years, but one to three is the norm, with the youngest often used for further stylistic application.
A well-aged lambic serves up a multitude of distinct notes. They are vinous, fruity, musty, acetic and lactic all at once, with other minor constituents mingling about. Straight, traditionally brewed lambic is served uncarbonated from a cask in its most pristine form, ideally in greater Brussels. All things considered, it is truly an acquired taste, and a written column does little justice to the profile and experience. Lambic has two other incarnations that are more than worthy of mention. They are the rowdy and spirited gueuze, and fruit lambic, formulations of straight lambic that offer something a little more familiar and tame to those who can’t wrap their palate around the unaltered, purist originals.
Gueuze is a blend of old and young lambic, usually a mixture of one-, two- and three-year-old . After blending, the mixture is roughly filtered, but not entirely, to leave some of the vital bugs, and then bottled. The youngest (fox lambic) offers some unfermentables to the old lambic (vieux lambic), which in turn gives the product a rambunctious effervescence during bottle conditioning not unlike champagne. In fact, gueuze was initially inspired by the méthode Champenoise in the nineteenth century to make lambic more appealing to the masses.
Blenders are skilled artisans as lambic varies from batch to batch and even among casks within a batch. The blend and refermentation initiates yet another cascade of events within the bottle, initiated by the arousal of the different lambics. It is aged for three to nine months, and at least one summer, with the temperature swings being paramount to microbial activation. Gueuze is more than just a blend of lambic, but yet another distinct form of it.
As the name so simply implies, this is lambic laced with fruit. The most common are, in order, kriek (cherry), framboise (raspberry) and cassis (black currant). For kriek, local sour cherries, known as Shaarbeek, are preferred and most traditional. Their contrasting sour-sweet character meshes perfectly in lambic. The habit of fruiting may come from the ubiquitous agrarian practice of frugality and using every single morsel of labor. Fruit is nutritionally and calorically preserved in beer. Even dried fruit on the branch was used, and often preferred for its concentrated condition. The fruit is put into casks and fox lambic racked over, kick-starting another fermentation. The bung is stuffed with twigs to act as an airlock. After a few months, it is bottled with more fox lambic for carbonation.
If you haven’t already, explore these beguiling brews, for to appreciate lambic, is to appreciate the wild and genuine side of brewing.