I remember when I first began homebrewing back in 1986 and almost immediately wanted to start brewing all-grain. At that time the information related to homebrewing was a little more difficult to find and my quest for information quickly landed me in the stacks of McKeldin Library on the University of Maryland campus in College Park. There I found a bunch of texts that seemed so confusing to my young mind. Luckily I later found some homebrew books that helped demystify mashing.
The mashing method I cut my teeth on was the “simple” infusion mash. One mash temperature followed by sparging with hot water and onto the kettle wort flowed. Only later did I pay much mind to step mashing and decoction mashing. These days it seems that many homebrewers have thrown out the KISS philosophy and have replaced simplicity with complexity. I suppose I am a hypocrite for taking this view since I actively encourage commercial brewers who are building new brewhouses to invest in equipment permitting temperature profile mashing, but I really don’t believe that there is a compelling argument for most homebrewers to mess around with step mashing.
OK, so now that I have set the stage, onto the answer. You are describing the dilemma of an infusion masher, that’s you, who is peeking over the fence at what step mashers do. Step mashers tend to “mash-off” at the end of the mash before they move their mash to the lauter tun. Infusion mashers go straight from mashing to sparging and skip the mash-off step. So what’s the difference and why?
When mash is stirred in a mash mixer and pumped to a lauter tun it behaves differently than an infusion mash. As it turns out, wort separation is easier when the mash is heated or “mashed-off” before the transfer. This also serves to inactivate enzymes and allows the brewer to control mashing, stop the mash, then get on with wort separation. This is not necessarily a better method from infusion mashing, it’s just different. Most commercially brewed beer in the world uses some sort of stirred mash and lauter tun or mash filter for wort separation. Decoction mashing and the American double-mash used for dealing with solid adjuncts like rice and corn are both variants of stirred mashing.
In the infusion method there is no mash-off and hot sprage water, usually around 168 °F (76 °F), is sprayed directly on the mash bed after mashing. Since infusion mashing usually is conducted at 149–158 °F (60–70 °C), enzyme activity continues as wort flows from the mash tun to the kettle. Even when hot sparge water is sprayed on the mash bed the wort temperature in the kettle is never much hotter than the mash temperature due to heat loss. This method works very, very well and is the traditional method the British use to brew ale.
Discussions of yield improvement may include increasing the sparge temperature of infusion mashes to reduce wort viscosity and eek out as much extract as possible from the grain bed. There has been a lot of research related to tannin/polyphenol extraction associated with high sparge temperatures and some of the studies conducted in the mid-1990s convinced me that high temperature sparging is not the recipe for disaster that many believe. Most of this research also included milling methods, especially hammer milling, that have dramatic improvements on extract yield when combined with modern mash filter technologies. The take home message is that “hot sparging” can be used to produce high quality wort as long as the variables effecting tannin/polyphenol extraction, mainly pH, are controlled during sparging.
In practice, most brewers these days continue to sparge with water that is about 168 °F (76 °C) because it works well and brewers tend to be a fairly traditional lot. The old adage stating “if it ain’t broke, don’t fix it” is alive and well in the modern brewery.