A few weeks ago I made my first visit to Oxbow Brewing Company for samples and a quick brewhouse tour, on the way inside the brewery I spied a Koelschip sitting out front and realized I haven’t done a blog post about them yet.
Koelschip or Coolship is a large, shallow vessel in which hot wort (unfermented beer) is allowed to cool to ambient air temperature prior to fermentation, the act of cooling wort in this way also allows for naturally occurring wild yeast strains to inoculate the wort. Koelschips are old school brewing equipment often found in the production of traditional lambics.
Oxbow won’t be the only brewer in Maine using this piece of brewing equipment, Allagash Brewing Company in Portland, Maine was the first American brewery to build and use a Koelschip in the summer of 2008. Allagash currently produces three to four batches of beer a year using their koelschip, they would like to be producing six to eight batches a year but weather and temperature are key factors that determine how many times the koelschip see’s wort.
I contacted Dee Dee Germain at Allagash to get a feel for their process. She tells me that they brew a 15bbl batch of beer (about 465 gallons) which is roughly half the capacity of their old brewing system, comparatively their new brewing system operates at roughly 70bbl (2170 gallons). The wort (unfermented beer) is then pumped from the brewhouse into the koelschip room, which is located outside the brewery. The wort then rests in the koulschip for 8-10 hours before being transferred in to a stainless steel tank to be mixed before its final transfer into oak barrels. The finished product is determined by time and taste test and may be stored in barrels for months, even years before it is released.
Koulschip beer production is a time sensitive operation, Dee Dee tells me that they only use it in the spring and fall when the daytime temperatures are not too hot and the nighttime temperatures are not too cold so that the wort cools to a 60-65 degree range in the allotted time. I would also assume that this time frame works best for yeast collection which are also sensitive to temperature. Not implementing a traditional controlled brewhouse cool and exposing the wort to wild yeast seems like it would be a gamble and when you gamble often times you lose, but Dee Dee tells me “we have had to dump a few barrels over the years, not many, but a few.”
I had the opportunity to tour Allagash last summer before the Beer Bloggers Conference pre-excursion in Portland. It’s an interesting facility to tour because you step into a shiny new brewery with elevated catwalks and then walk around the corner to view their original brewhouse which is considerably smaller but still used today, then proceed past the fermentation vessels and on to the bottling line.
We got to do the extended tour and visited the Koulschip which is outside the brewery, tucked out of the way, to the untrained eye it looks like a small groundskeepers shed with ornate stained glass windows, but inside there are no gardening tools or lawnmowers only a small walk way that runs the length of the room, the rest of the room is consumed by the large stainless pan that is the koelschip, a pipe that enters from the brewery over into the Koulschip. Around the top of the room are stained glass windows that are propped open to allow heat to escape and air to flow in, screens keep insects and birds out. It’s one of those things that only a true beer geek can appreciate, otherwise it’s a shack with a large stainless trough in it. The tour ended in the wild barrel room, which had a small bar near the entrance for sampling and the rest of the room was devoted to stacks of barrels that rise up to the ceiling and giant foudre’s filled with beer.
Allagash Coolship beers are limited release and pop up from time to time at the brewery store, a Coolship Cerise with Montmorency and Balaton cherries was the most recent release on July 14, 2014, follow their Facebook page for release dates and keep an eye on the boys in Newcastle. I reached out to Tim Adams at Oxbow to find out about their foray into the world of wild yeast collection “First truly wild yeast project! Safe to say curiosity got the best of me” said Tim “firing it up this fall”. I have a good feeling about the“Goods from the Woods” with a Koelschip twist, the woods are usually where the wild things are found.