Lambic is a very distinctive type of beer brewed only in the Pajottenland region of Belgium (southwest of Brussels) and in Brussels itself. Lambic is now mainly consumed after refermentation, resulting in derived beers such as Geuze or Kriek. Most modern beers are fermented by carefully cultivated strains of brewer"s yeasts, Lambic"s fermentation, however, is produced by exposure to the wild yeasts and bacteria that are said to be native to the Senne valley, in which Brussels lies. The beer then undergoes a long aging period ranging from three to six months (considered "young") to two or three years for mature. It is this unusual process which gives the beer its distinctive flavor: dry, vinous, and cidery, with a slightly sour aftertaste.
Lambic can be broken into three subclasses: Gueuze (oud Gueuze and Lambic), Fruit Lambic, and Faro.
The first of these, gueuze, blends both old and young mixtures to stimulate a second fermentation. Many are laid down like fine wines to age for several more years. In its most natural form, Lambic is a draught beer which is rarely bottled, and thus only available in its area of production and a few cafes in and around Brussels. Some more mainstream brewers elude the orthodox rules of lambic production, adding extra sugars to sweeten their beers. Gueuze, also known informally as Brussels Champagne, is a sparkling beer produced by combining a young Lambic with more mature vintages.The majority of flavored beers are made on base of Lambics. The last of the Lambic brews, Faro, adds sugar or caramel to prompt the fermentation.