Beliner weisse suffered the same fate as many regional beers during the latter half of the 19th century, muscled aside by the invasion of pale lagers. It withstood the storm long enough to find port in the rapidly developing disciplines of fermentation science and microbiology to maintain their identity. Berliner weisse was not spontaneously fermented, but inoculated instead by the brewer, and identifying the organisms and conditions responsible was paramount to properly perpetuating the style. Biochemist Max Delbrück, while working at the Institute for Brewing in Berlin between 1932 and 1937, isolated the potent souring bacterial strain crucial to the style. It was dubbed Lactobacillus delbrückii, a common contributor also to lambic, gueuze, Flemish sours and the new North American Wilds.
Berliner weisse has not seen quite the same revival that many other older beer types have of late, but is still in a happier place than a generation ago. There are now several brewers in Germany making Berliner weisse (three in Berlin), some of which are a bit outside the modern stylistic norm, and more like older versions. Most are brewed and fermented in traditional fashion, with parameters and methods collectively unique to the style; minimal wort heating, single digit IBUs, low original gravity, top- and lactobacillus-fermentation, warm and cold conditioning, extreme attenuation, krausening, bottle-conditioning and prolonged maturation (often in stainless steel vessels).
The proportion of malted wheat has dropped to 30 from 50 percent. Wort is boiled for a very short time or kept just below the boiling point. This serves to sanatize the wort while retaining protein components critical to nutrition and metabolism of essential lactobacillus. Conventional top-fermenting yeast is pitched with Lactobacillus delbrückii and fermented at standard temps. After the proper attenuation is achieved, wort is sent to conditioning tanks and kept either warm or cold, depending on the brewery, perhaps with a shot of krausen. The conditioning beer continues to attenuate under the influence of lactobacillus and also develop its sour sharpness. It is then krausened again and bottled, and never pasteurized, encouraging metamorphosis in the bottle. Attenuation can approach 100 percent, leaving it extremely dry, with an ABV of 2.7 to 3.5 percent. This otherwise delicate beer with a piercing and puckering edge is usually softened with fruit syrups (mit schuss) in its homeland. Either the herbal green woodruff (walmeister) or red raspberry (himbier) are the most common. Those who have had their palates jaded by other assertive sour brews may find Berliner weisse fine without the sweet softeners. Berliner weisse has the legal protection of appellation d’origine contrôllée, the same as kölsch has in Köln. On this side of the pond, there are a couple of very common ones, Dogfish Head Festina Pêche and The Bruery Hottenroth, as well as a fair number of one-offs and experimentals. As brewers learn to tame and employ the “savage” lactobacillus, we may see more of these in the future.
The style is ready for a reawakening, and even savvy reworking. A more pleasant, refreshing marriage of sour and sweet does not exist.