The Methods of Mashing
Decoction Mashing is a way to conduct multi-step mashes without adding additional water or applying heat to the Mash Tun. It involves removing about a third of the Mash to another pot where it is heated to conversion temperature, then boiled and returned to the Mash Tun. The portion removed should be pretty stiff, no free water should be showing above the top of the grain. This procedure accomplishes three things. First, the addition of boiling hot gruel to the main mash raises the temperature of the mash to the next rest. Second, the boiling process breaks up the starch molecules of the unconverted grist and produces a higher degree of extraction from moderately-modified continental malts. Lastly, it makes it possible to achieve the crisp, dry maltiness characteristic of German Oktoberfest and other continental lagers. For more information on Decoction Mashing, see the Recommended Reading Section in the Appendix.