Learn from our Brewers about the style, ingredients, and brewing process behind one of our latest Beer Hall Exclusives.
Polotmavý, quite literally meaning “half dark”, is a Czech style of amber lager. Brewed with a mixture of floor-malted bohemian pilsner and floor-malted bohemian dark malt, this beer will finish with a beautiful amber hue. But wait! What is floor malting, and why are we coolshipping a lager that isn’t meant to be spontaneously fermented?
Floor malting is an uber-traditional method of hydrating barley to induce germination. After the grain has been steeped in water, enzymes activate to begin the process of breaking down cell walls and proteins. This “modifies” the structure of the barley and allows starches to become accessible for conversion to sugars. The hydrated grain is then spread evenly across a smooth concrete floor to wait for the process of germination to begin. Over the course of several days, the grain is periodically turned over by hand to maintain steady conditions. If allowed to go too far, the seed will begin to consume sugars and grow into a lovely plant. Modern industrial techniques are significantly better at maintaining a controlled climate with adequate humidity, so floor malting tends to result in an “under-modified” product. So how do we get around that?
First, we mash in at a protein rest of 131 degrees F. This helps to break down larger proteins into smaller chains and amino acids. An enzyme called protease can help to reduce chill haze and to improve head retention, while an enzyme called peptidase works to provide amino acid nutrients for the yeast that ferments our beer. Then we decoct! This is achieved by separating a portion of the mash, bringing it to a boil, and reintroducing it to the remainder of the mash to achieve gradual steps in temperature. The boiling breaks up the not fully modified portion of the malt, and introduces maillard reactions that create a bready, caramelized, melanoidin quality to our finished beer.
“Traditionally”, in America, one of the final steps of brewing is the whirlpool. Before we knock out our wort and rapidly cool it to more ambient temperatures, we spin it around to pool trub (proteins and polyphenol) into a tight cone that separates from the rest of the wort. But where’s the fun in that? Enter coolship. Instead of spinning our wort, we bypassed the whirlpool altogether. We gravity-fed from the kettle, at boiling temperature, into a large and shallow open vat known as a coolship. Over the course of an hour or so, the surface area of the coolship allows rapid evaporation of water to dramatically increase the sugar concentration of our wort. It also allows all of those nasty long-chain proteins and polyphenols to gently fall out of the solution, producing a brilliantly clear wort that is ready to ferment without unwanted bitterness or astringency. Because the coolship is an open vessel, it is crucial that the temperature of the wort remains above pasteurization temperatures before being pumped through the heat exchanger into the fermenter. Otherwise, it could become infected with wild yeast and bacteria, resulting in a souring effect.
