Well the firt piece of information I will supply is that there is no reason with any of the malts we can get nowadays to do a stepped mash . . . apart from flavour development. The traditional reason for stepped mashes was to allow the breweries to use poorly modified malts that would yield a very low level of extract if mashed in the traditional infusion techniqueLeicesterLad said:
There are several ways to accomplish a stepped mash, and the simplest is just to add additional boiling water to raise the temperature from one rest to the next. It is really of benefit going from say 62 (beta amylase rest) to 67 (alpha amylase rest) and 67 to 72 (mash out), you don't need a massive amount of additional water, and if you start with a thicker mash than you would normally do (say 2L/Kg) then going to 3L/Kg is not necessarily a problem. . . . However you do need a bigger mash tun to do this successfully . . . and this technique doesn't work to develop melanoidin flavours . . . It can be used successfully for the glucan rest or the Ferrulic acid rest though in a wheat beer or Oatmeal stout.LeicesterLad said:
Moving on from infusion stepped mashes you come to the classic method of decoction. Where you take a portion of the main mash (always the thick portion, leave the liquor behind, that's where the enzymes are). and raise it using direct heat, pausing at each of the remaining temperature steps . . . before raising it to boiling and adding it back to the main mash to bring the main mash up to the next rest temperature. . . . It develops wonderful melanoidin flavours that really accentuate the malt. . . it is time consuming and can burn on the pan during the heating.
Direct heating of the mash is possible if your tun is designed right, so you turn on the heat stir to ensure scorching doesn't take place and turn off the heat when the rest temperature is obtained. It is very quick and easy to do, and effective . .not that good with electric mash tuns . . . although with a dilute mash of around 3-4l/Kg it is very effective, and I believe it's possible to do it with Brew In A Bag technique, but I've not tried it myself.
As an extension of this you come the the RIMS and HERMS world . .. where the mash liquor is continually recirculated via a pump, from the bottom of the mash tun through the pump into a 'heat unit' and back to a return manifold at the top of the tun. The heat unit is controlled by a PID temperature controller that applies exactly the right amount of 'heat' to the wort to raise the temperature to the next step in a safe manner without overshooting the set temperature . . . once properly 'tuned' these systems are really set and forget.
