Beer - Chilling The Wort
This type of system dramatically decreases the risk of contamination during cooling since the wort is only exposed to the environment while it is still too warm for microorganisms to survive. When the wort becomes vulnerable to contamination (at temperatures below 140 degrees F) it is in a closed system, protected from outside sources of contamination. For additional protection, surface coolers are usually housed in specially constructed rooms where sterile filtered air is continuously circulated and precisely controlled to prevent condensation. The walls and ceiling in such facilities are typically lined with porous bricks to absorb moisture and the ceiling is insulated as a further protection against condensation.
As mentioned previously, coolships are still used by a few small, traditional breweries, especially in Belgium and Bavaria. In traditional lambic brewing, the coolship is something of a necessity. Coolships in Belgian lambic breweries are typically located in the attic, where the windows are left open, and often, parts of the roof are missing or the roof is fitted with slatted ventilators. Here, the wort is left to cool overnight, during which time it becomes naturally inoculated with the wild yeasts and other microorganisms so crucial to the development of the character of the style.
The Cantillon Brewery in Brussels, Belgium is an excellent example of a traditional lambic brewery. Although the brewery dates only from 1937, Cantillon adheres to traditional lambic brewing practices. They use a copper coolship that's about ten inches deep, 12 feet wide and 15 feet long. It is located on the top floor of the brewery where the slatted roof permits entry of the appropriate micro flora.
The Traquair House Brewery of Innerleithen, Scotland is one of the smallest and most primitive breweries in the world. The brewery is housed in the oldest inhabited building in the country, parts of which date from 1107. Though the present brewery was started in 1965, brewing was conducted there at least as early as the middle of the sixteenth century. When the house's present owners discovered the brew house tucked away in one of its many rooms, they revived the tradition of brewing. Although it was antiquated, they decided to use most of the original brewing equipment. A receipt for the kettle is dated 1738. Also among this equipment was a small, wooden coolship which is still used today. The wort spends less than an hour in the coolship before being pumped through a baudelot cooler. The use of such antiquated equipment is credited in part for the house character of the distinctive beers produced by Traquair House.
But, by and large, the coolship is a thing of the past that would certainly be out of place in today's modern breweries. Or would it? Just a few years ago the Sleeman Brewing Company of Guelph, Ontario had a half million-dollar custom coolship designed and constructed so they could authentically recreate a historical steam beer recipe. The new coolship was installed in a specially designed sterile room which was also built specifically for this special brew. According to Sleeman, steam beer was named for the steam that rose from the huge coolships used to cool the beer. Sleeman Steam beer was introduced in 1999.