Kellerbier is a beer that merges the best of British cask ale with German malts and hops in a unique lager style. It has an atypical flavor profile that, depending on your finishing steps, can represent itself as a kind of German ESB or a Continental IPA. Because it’s a relatively new style to the U.S. craft and homebrewing market, you might have trouble finding commercial or homebrewed versions to compare yours to, but this version should get you pretty close to the mark!
Style
There’s some dispute over whether Kellerbier is an actual style of beer or a production/serving method. Strictly speaking, Kellerbiers are cold-fermented (in cellars), bottom-fermenting beers that are generally served young and unfiltered. Many are also served with low levels of residual CO2, having been matured in vented casks that retain very little carbonation in the beer. For our purposes, though, you can refer to the “Amber Kellerbier” descriptions in the 2015 BJCP guidelines for a sense of the target flavor profile. It’s essentially an amber lager that differs from Oktoberfest in the relative intensity of its hops character across all fronts—bittering, flavor, and aroma. It is also unique in that a touch of acetaldehyde and other “green” beer flavors are not necessarily considered a fault (though we’re going to avoid them here).
A strict reading of the guidelines also suggests that the beer should have moderate carbonation, but we’re going to deviate from that (in the interest of historic authenticity, and, I think, enjoyability). If you plan to enter this beer in competition, you’ll want to carbonate to a full 2.5 volumes, at least for the bottles to be entered!