Between Lagers and Ales: Hybrid Beers
Beers can have mixed parentage. These types of beers have been dubbed hybrid beers, and they exist due to brewers’ flouting of conventions by fermenting a beer with lager yeast at ale (warm) temperatures and fermenting a beer with ale yeast at lager (cool) temperatures.
Warm fermentations with lager yeast
Finding the exact temperatures used to produce hybrid beers and how long the beer is fermented and aged isn’t an exact science. The processes vary from one brewer to the next, as do the beers they create.
Not a lot of beer styles represent this type of hybrid. The most famous style is known as Steam Beer, but because the San Francisco brewery that popularized the style also trademarked the name Steam Beer, the style is now generically referred to as California Common Beer. (The Steam Beer style is also recognized as Dampfbier in Germany.
Though it can no longer be confirmed, one theory suggests that the origination of the steam label had to do with the vigorous warm fermentation that caused the vessel to hiss, or steam, while venting the increasing carbon dioxide inside it.
Cold fermentations with ale yeast
Ale yeasts, when fermented at warm temperatures (the usual process), tend to produce fruity flavors and fruity or floral esters (aromas). When beers are fermented with ale yeast at colder temperatures, however, the yeasts’ production of esters is reduced, thereby producing a beer with a more subdued aroma and refined flavor that mimics lager beers.
Because brewers tend to have individual ways of doing things, pinning down the exact fermentation temperatures or lengths of fermentation of these beers is difficult. Thus, you can expect individualistic beers from these guys as well.
The three most common beer styles in this hybrid category are Altbier, Kölsch, and Cream Ale. The first two styles are of German origin, and the last one is uniquely American.
Baltic Porter is kind of in a class all its own. Typically, Porter is considered an ale and is warm fermented. Many brewers who make Porters in the Baltic States like to cold ferment their beer, though — most often with lager yeast but occasionally with ale yeast, too. Go figure.