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Mashing
Mashing Equipment
There are a number of configurations of mashing systems employed by brewers. Mashing is performed in a mash tun when an all-malt wort is being mashed or in the special case of a pregelatinized or liquid adjunct being employed. If pregelantinized adjuncts are not used, a double-mash system that employs a cereal cooker and mash tun is required. Although mash tuns can be used for lautering, some breweries have installed lautering vessels for greater flexibility. Temperature-controlled and decoction mashing require separate conversion and lautering vessels. In temperature-controlled and decoction mashing, a lautering system separate from the mash tun is needed to apply heat directly to the mash tun.
Holding Hopper
A holding hopper (often called a scale hopper) for grist is mounted above the cereal cooker or the mash tun. Hoppers are usually equipped with vibrators to aid in the emptying process. They have automatic load cells for exact weight measurement (to an accuracy of +/- 1%). A dust collection system or a breather filter is installed on the holding hopper in order to minimize the dust.
Cereal Cooker
Cereal cookers are usually stainless steel vertical cylinders equipped with a variable-speed agitator, as shown in Figure 9.1. A water station controls the temperature at mash-in as well as the proper grist-to-water ratio. Heating is done by steam jackets on the side wall and bottom of the vessel or by the less sophisticated method of direct steam injection. The side and bottom jackets can operate independently for optimum temperature control. Some cereal cookers are equipped for pressure boiling. The cooker is usually insulated and equipped with temperature probes accurate to +/- 0.25ºC. Modern cereal cookers have permanent cleaning-in-place (CIP) systems. A sparge ring that enables contents to be rinsed after the transfer is located at the top of the vessel.
Mash Tun
British brewers use the same vessel – commonly referred to as the "mash tun" – for both mashing and mash filtration, as shown in Figure 9.2. Among craft brewers, the mash tun is the preferred equipment for both mashing and wort filtration. Mash tuns are made of stainless steel and are equipped with a sparge arm for spraying high-temperature water (sparging) over the mash bed to displace the extract at the end of the mashing cycle. This dilutes the sugar solution and washes out the extract. The sparge arm consists of concentric pipes suspended just below the ceiling of the tun. The pipes are equipped with spray nozzles directed downward to deliver the sparge water in a uniform pattern over the entire surface area of the mash bed. The wort collection system is fitted into the bottom of the mash tun. It is equipped with a slotted false bottom that is supported a few inches above the true bottom, with the total slot area typically totalling about 11% of the filter-plate area. It also consists of runoff pipes arranged in concentric rings that lead through a system of valves. Through these the wort is delivered to a collection vessel called a "grant" or directly to the kettle.
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