The wonders of lambic beer

If there is one beer style that can compete with wine in terms of complexity it is the lambic beer. Unfortunately, if lambic beers are known at all, it is typically because the name is also used for the sweet fruit beers that are produced by some macrobrewers. Traditional lambics, however, are rarely sweet and often quite sour. As a matter of fact, it is this sourness and spontaneous fermentation that distinguishes lambic beers from most other contemporary beer styles.

In 1996, Scientific American published an article by Jaques De Keersmacker called “The Mystery of Lambic Beer.” The blurb of the article says: “An ancient brewing technique produces a beverage so complex that it is still yielding its secrets to organic chemists.” In the article the author introduces the reader to the rich history of lambic brewing and discusses the complex organic chemistry of lambic.

Although lambic beers may be a “living anachronism” today, most beers were once brewed by exposing grains to the wild wind-borne yeasts in the area. 5000 years ago an alcoholic drink called Sikaru was made with roughly the same ingredients and proportions as traditional lambic. No hops were used in these brews. Contemporary lambic brewers do use hops, but only aged hops to preserve the beer, not to add flavor. The flavor of lambic beers solely reflects the (local) spontaneous fermentation of barley malt and unmalted wheat.

During fermentation, a variety of wind-borne and local microorganisms  in the barrels convert the wort into ethanol,  carbon dioxide and acids. Food scientists and organic chemists have identified a number of overlapping stages during fermentation of lambics: first, enteric bacteria and wild yeasts proliferate, followed by alcohol and carbon dioxide production by Saccharomyces. During stage three, lactic and acetic bacteria (such as Pediococcus) proliferate, giving lambic its distinctive sour taste. During the fourth stage, the dominant yeast is of the Brettanomyces genus, which is the microorganism that is associated with the distinct “farmhouse/barnyard” taste of lambic.  During fermentation a film forms on the surface of the brew that prevents oxygenation and excessive proliferation of acetic bacteria. And, as if nature “intended” to create lambics, the alcohol and low pH in turn prevent the proliferation of enteric bacteria.

Although the resulting product, “straight lambic,” can be enjoyed in some local pubs in Belgium and is sometimes bottled (Lambic breweries and blenders Cantillon and De Cam have bottled aged lambic), it is usually blended with other lambics to produce gueuze (or geuze). The traditional lambic brewer blends lambic of various ages (for example 1, 2 and 3 years) to induce additional fermentation in the bottle. The resulting gueuze is sour, dry and complex. Another popular lambic style is to add whole fruits to  a young lambic to induce a second fermentation. The most  popular variety is Kriek, which is made by adding (sour) cherries to the lambic. Such lambics may smell sweet but the long fermentation period produces the distinct tartness, but with subtle aroma differences, of the unblended lambics or gueuzes.

Unfortunately, these traditional fruit fermented lambics often have to compete (if available at all) with beers to which fruit syrup is added to a lambic base, or even to another type of beer. Although there is a growing market for such beers, the shared use of the name “lambic” has the unfortunate effect that the traditional lambics, which require long production times (2 years or more) and reflect a unique brewing process, have to compete with such “simplistic” sweetened brews. Ironically, the increased popularity of these “lambics” have raised renewed interest in traditional lambic brewing, such as practiced by Belgian brewers and blenders like Cantillon, 3 Fonteinen, Oud Beersel, De Cam, and Hanssens.

As one book says, lambics are beers beyond  the influence of brewer’s yeast (hence the importance of blending to create a consistent product). The author of the article reports that researchers at the University of Leuven in Belgium have identified 100 different kinds of yeast colonies, 27 colonies of acidic bacteria, and 38 colonies of of lactic bacteria in a single type of lambic. Such complexity is an exciting field of research for organic chemists and curious “molecular brewers.”

De Keersmaecker ends his article as follows:

“Lambic’s future rests with adventurous beer lovers and that small but enthusiastic segment of the population that goes out of its way to sample traditional ethnic foods. Lately this group seems to be expanding as more people pass up processed foods in favor of the old staples: fine cheeses, hearty breads, wines, abbey beers and real ales. Who knows? If the trend continues, lambic may be around for another 500 years.”