Lambic is a type of beer brewed traditionally in the Pajottenland region of Belgium (southwest of Brussels) and in Brussels itself at the Cantillon Brewery and museum. Lambic is now mainly consumed after refermentation, resulting in derived beers such as Gueuze or Kriek lambic. Unlike conventional ales and lagers, which are fermented by carefully cultivated strains of brewer’s yeasts, lambic beer is produced by spontaneous fermentation: it is exposed to the wild yeasts and bacteria that are said to be native to the Senne valley, in which Brussels lies. It is this unusual process which gives the beer its distinctive flavour: dry, vinous, and cidery, usually with a sour aftertaste.

Today the beer is generally brewed from a grist containing approximately 70% barley malt and 30% unmalted wheat. When the wort has cooled, it is left exposed to the open air so that fermentation may occur spontaneously. While this exposure is a critical feature of the style, many of the key yeasts and bacteria are now understood to reside within the brewery and its (usually timber) fermenting vessels in numbers far greater than any delivered by the breeze. Over eighty microorganisms have been identified in lambic beer, the most significant being Brettanomyces bruxellensis. The process is generally only possible between October and May as in the summer months there are too many unfavourable organisms in the air that could spoil the beer. Since at least the 11th century and probably earlier, hops have been used in beer for their natural preservative qualities as well as for the pleasant bitterness, flavor, and aroma they impart. Today it is the latter that is the reason for their inclusion in almost all beer styles other than lambic. Since the method of inoculation and long fermentation time of lambic beers increases the risk of spoilage, lambic brewers still use large numbers of hops for their antibacterial properties. To avoid making the beer extremely bitter, however, aged, dry hops (which have lost much of their bitterness) are used. Consequently, lambics often have a strong, cheese-like, “old hop” aroma, in contrast to the resiny, herbal, earthy hop bitterness found in other styles.

Pictured above is a Lindemann’s Pomme (apple) Lambic.