Steam beer may be defined as a highly effervescent beer made by brewing lager yeasts at ale fermentation temperatures. It has two distinct but related meanings:
- Historic steam beer, by all accounts bad-tasting, produced in California from the mid-1800s to the mid-1900s;
- Modern California Common beer, the official name for the beer family which includes Anchor Steam® beer.
Historic steam beer, associated with San Francisco and the U. S. West Coast, was brewed with lager yeast without the use of refrigeration. It was an improvised process, originating out of necessity, perhaps as early as the Gold Rush. It was considered a cheap and low-quality beer, as shown by references to it in literature of the 1890s and 1900s.
Modern steam beer, properly known in the brewing community as California Common beer, was originated by Anchor Brewing Company, which trademarked the name Anchor Steam® Beer in 1981. Although the modern company has corporate continuity with a small brewery which was still making traditional steam beer in the 1950s, Anchor Steam beer is a craft-brewed lager. The company does not claim any close similarity between it and turn-of-the-century steam beer.
Explanations of the word "steam" are all speculative. The carbon dioxide pressure produced by the process was very high, and one possibility is that it was necessary to let off "steam" before attempting to dispense the beer. According to the Anchor Brewing Company, the name "steam" came from the fact that the brewery had no way to effectively chill the boiling wort using traditional means. So they pumped the hot wort up to large, shallow, open-top bins on the roof of the brewery so that it would be rapidly chilled by the cool air blowing in off the Pacific Ocean. Thus while brewing, the brewery had a distinct cloud of steam around the roof let off by the wort as it cooled, hence the name. (Full article...)