Strainmaster | The Oxford Companion to Beer

is a device developed and patented by Anheuser-Busch in the late 1950s to separate the solids in the mash—the spent grain—from the liquids—the wort that becomes beer. It essentially functions as an alternative to traditional lauter tuns and mash filters. The Strainmaster is a large rectangular vessel with inward-sloping walls that form a hopper-like enclosure at the bottom. The lower portion of the vessel contains several wort lines, each equipped with a series of draw-off tubes (so-called fins) that are perforated to allow wort to enter the tube while keeping grain particles out. For straining, mash is pumped into the Strainmaster from the top, and once the wort lines and draw-off tubes are covered, wort is drawn off and recirculated back over the top of the grain bed, similar to “vorlaufing” in a lauter tun. See vorlauf. Once the wort runs clear, it is diverted to the kettle, while wort clarity and gravity are monitored at a grant. The draw-off rate for each wort line is adjusted for maximum straining efficiency. As with conventional mashing and lautering techniques, the grain bed in the Strainmaster is sparged with hot liquor to completely flush out all usable extract. See sparging. When the kettle is full, straining is stopped and the hopper bottom opens up, emptying the spent grain into a receiving tank below. The Strainmaster is then hosed down before it is filled with the next mash. The key advantage of the Strainmaster compared with conventional lautering techniques is its drainage speed. Whereas lautering my take 90 to 120 minutes, the Strainmaster usually accomplishes the same task in about an hour. Because the Strainmaster can operate with fairly deep grain beds, it takes up only about half the floor space of a conventional lauter tun. The Strainmaster has a few drawbacks, however. Because it has no rakes or knives to loosen up highly compressed grain beds, it lacks the tools to alleviate a stuck mash. It also produces 5% to 8% less extract than a lauter tun would from the same grain bill, which is one reason why even the Strainmaster’s inventor, Anheuser-Busch, abandoned the concept during the 1980s.