At Oliver Breweries at the Pratt Street Alehouse, in downtown Baltimore, Maryland, the beer is fermented in open vats. Viable yeast is skimmed from the uppermost, spumous, layer of the fermenting beer —called kräusen (pronounced KROY [like boy] zen) —and used to ferment the next batch of beer.
Here, the fermentation, although still quite active, has already passed the most active stage of fermentation called high kräusen. Notice the yeast and protein crust on the side walls of the fermenter, above the active yeast layer.
Open fermentation is traditional method of fermentation, unlike the current practice of almost all breweries in the U.S. —and worldwide— of fermenting beers in closed vessels, and collecting the yeast after fermentation in cone-shaped sections at the bottom of the fermenters.
11 February 2011.
- Pic(k) of the Week: one in a weekly series of personal photos, often posted on Saturdays, and often, but not always, with a good fermentable as a subject.
- Commercial reproduction requires explicit permission, as per Creative Commons. For non-commercial purposes, no permission is required (but kindly link back).
- Caveat lector: As a representative for Select Wines, Inc. —a wine and beer wholesaler in northern Virginia— I sell the beers of Oliver Ales.