Besides lagers and ales, there is lambics.
Lambic beer is produced using wild yeast, instead of the carefully cultivated yeast used with most commercial beers. It is the product of spontaneous fermentation.
Lambics, first of the great triad
Beers are most commonly divided into two great classes, ales and lagers, depending on the yeast strain used in fermentation. But most ale and lager yeasts are cultured, with many hybrids and sub-types and sometimes the classification is a little forced.
There's one type, however, that clearly stands apart: Lambics. True Lambics are made only from wild yeasts, and only those grown in a very specific region in Belgium, the Payottenland southwest of Brussels, Belgium.
Here nature has generously provided a strain of fungus - all yeast is this type of unicellular organism - in the Senne Valley that forms a key component in beers produced here. The special techniques employed have a long and honored tradition, passed down from generation to generation since medieval times.
In a deviation from ordinary brewing practice, when the wort is cooled, the liquid malt fermented by adding yeast, it is deliberately exposed to air. Spontaneous fermentation then occurs. Brewing this way is done only between October and May, to prevent the introduction of unwanted bacteria.
The result is a fruity brew, delightfully acidic and tart, almost like cider. Served with a sharp cheese and brown bread, Lambic drinkers have the opportunity to experience the perfect taste experience.
Those looking for a standard taste will be disappointed, though. Every batch is unique, owing to the use of wild yeasts and the natural fermentation process.
There are several other differences between Lambics and conventional brews, from differences in ingredients to fermentation and storage techniques to aging.
To the usual raw materials is added raw wheat, which makes up about a third of the total. During fermenting, yeasts from the walls and storage casks 'infect' the beer to carry out fermentation. Unlike the vast majority of beer brewing, casks are wooden, often oak, sometimes having been used to transport wine and often 100 years old.
Fermentation typically takes place over a much longer period. Ales ferment in about a week or two, lagers for perhaps as long as a month or so. Lambics may take two to three years to complete.
Homebrewers and connoisseurs are blessed with another byproduct of the process: many Lambics age as well as wine. Kept in the proper conditions, some Lambics are actually better after 20 years than when drunk fresh.
The genuine article was once heinously difficult to find, but with the growth of the Internet importation is easier. Good copies that respect the name by using Lambic-style or pseudo-Lambic are also more common than in decades past. Lambic yeasts can be purchased by home brewers, as well.
But for the best experience a visit to Brussels is in order, where the brew is served at the Gueuze Museum housing the still-operational Cantillon Brewery. Several styles, such as the well-known gueuze and kriek, are served.
Tip a glass to the ancestors who left such a delightful brew.