Temperature-Programmed Mash is commonly used in modern brewhouses as an efficient means of converting the starch, polysaccharides, and protein material in malt and in other cereal adjuncts into soluble form that can be rinsed by sparging to the wort kettle ready for boiling. See sparging. Unlike the older “single temperature infusion mash” which combines the mashing, conversion, and run-off of the wort into one non-heated vessel, called a “mash tun,” a temperature-programmed mash takes place in a vessel called a mash mixer, often called a conversion vessel. This vessel has heating panels that are used to heat the mash as it goes through the enzymatic conversion process; it also has a specially designed mixer to ensure thorough mixing and temperature distribution through the mash. The temperature program will vary according to the brewing recipe and the type of malt specified. If the malt used is “undermodified” (e.g., traditional lager malt), a program might include mashing in warm at 40°C–45°C and holding for 45 min, followed by heating to 62°C–65°C for 45 min for saccharification, before a final heat rise to 75°C. At this point the mash is transferred to a lauter tun or mash filter for sparging (rinsing the dissolved malt contents) to the kettle. “Well-modified” malts, such as American lager malts and British ale malts, will tend to have shorter holding times and fewer temperature set points. The different temperatures coincide with the enzyme activity for working on different constituents in the malt (e.g., proteases break down protein and are most active at about 45°C), whereas amylases that convert starch to small glucose units are most active at 61°C–67°C. Some beers have three holding temperatures and are mashed in at 35°C. The mash is heated to 75°C because at this temperature enzymes become deactivated and the wort viscosity decreases, which speeds up wort run-off. Temperature-programmed mashes can also be used to finely tune wort composition. For example, when brewing weissbier some Bavarian brewers will use mash rests that favor the development of organic compounds that yeast will later transform into aromatics typical of that beer style.