Anchor Brewing’s Tale of Open Fermentation

From Anchor:

As the process of brewing continues to evolve with modern technology, San Francisco’s Anchor Brewing Company remains one of very few US breweries that uses traditional open fermentation techniques on a commercial scale, bringing their brewing heritage from the California Gold Rush into the 21^st Century. As San Francisco’s oldest brewery,Anchor strives to find a balance between upholding the time-honored art of hand-crafted brewing and implementing carefully applied, modern methods. Fermentation is one area where Anchor artfully blends old and new—carrying out the traditional process of open fermentation, but with modern equipment and state-of-the-art industrial hygiene.

Fermentation is an integral part of the brewing process. In modern brewing, fermenters are typically enclosed in stainless steel tanks, and the entire process takes place within. Before the advent of modern metals, however, beer was fermented in tanks or vats that were mostly made of wood. Some were lined with copper or otherwise sealed and all were either open to the air or vented for pressure relief. Prior to mechanical refrigeration, basically before 1900, lager breweries would run the hot wort from the brewhouse into these wide shallow vats to facilitate cooling before moving it on to the actual fermenter. These “coolships” were adopted by the pioneering breweries of the gold rush years in California, including Anchor Brewing.

Although Anchor has modern equipment and their fermenters are made of stainless steel, Anchor has kept the open fermentation process as part of their heritage. Anchor uses this technique for several of their beers, whether lager or ale (although the design for ale fermenters are different). Since all Anchor fermenters are open to the air, the brewers must maintain a very high standard of cleanliness in the brewery. It takes more work, but Anchor believes that open fermentation is a tradition worth maintaining. Anchor brewers are steadfast in upholding their traditions, but they are also adventurous and pioneering in the way that they brew. While they continue the age-old process of open fermentation, for example, they are simultaneously on the forefront of new brewing technologies like cavitation—a process used in the brewing of fruit beers to maximize the extraction of the fruit.