DesertBrew, all,
This is exactly the kind of discussion we want to have in this thread and I'm thankful that it came up because I have run into this many times already.
How do we justify step mashes?
First of all, lets be generic and consider all the other possible rests that you can have in a mash. So far the focus was on protein rests (as the title suggests)
Dough-In at room temp: Enzymes go into solution
some sources suggest that there is a benefit to this. But I don't think that it should be done unless you have a mash system where this can easily be done
40C (105F) - Acid rest: acidification of the mash if necessary. and BetaGlucanase which helps breaking down cell walls
The acidification can be utilized if you don't want to use artificial acidifiers or acid malt. The BetaGlucanase will be important if your are using a significant amount of adjuncts (unmalted grain). But many of us are not using enough adjuncts to justify a BetaGlucanase rest.
50C (122F) - Protein rest: Proteolytic enzymes break down long and medium long chained proteins.
This is the most debated rest. Extending it for to long can be detrimental for head retention due to the degradation of medium long proteins. Even passing this range during heating the mash could be to long. This is why some brewers suggest mashing in above this rest or skipping this temp range by raising the temp with a hot-water infusion.
It should be employed if you use lot's of adjuncts and/or the soluble nitrogen ratio is below 40% (according to Noonan). Most British and American malts should be modified enough to have a SNR of >40%.
60-63C (140F - 146F) - Maltose rest: Since mostly the beta-amylase is working, mostly maltose will be produced. This is a rest that you can find in many German mash schedules for maltier beers. Since there is little alpha-amylase activity, the beta amylase will run out of dextrines/starches to convert before all the starch is converted. The amount of maltose generated is usually controlled by the length of this rest.
64-68C (148-155F) - combined alpha/beta amylase rest:
This is the single rest that you use for single infusion mashes. Both amylases work. Their activity can be controlled by the temp and the fermentability of the wort will be determined by rest temp and time. But the fermentability is fairly sensitive to the temp. This makes hitting a targeted FG with just one rest difficult as you need to be very precise with hitting the temp of the mash.
70-72C (158-162F) - Saccrification rest:
This rest is used in combination with the Maltose and/or combined alpha/beta rest if these rests did not result in the complete conversion of the mash. Especially in higher bodied beers this is intended. Only the alpha amylase works here and it will convert all the starches to dextrines. It may also produce glucose, maltose or matotriose if left at this rest for to long.
75C (168F) - Mash-out:
All enzymatic activity ceases and the fermentability of the mash is fixed. The Mash is less viscous which improves lauterting.
As you can see, not all of these rests are necessary or even desired. For English and American ales A single infusion mash with mash-out is the desired mash schedule. Everything else is neither authentic nor necessary.
German Lagers (with German malts) benefit from a step mash, but one has to be careful in not overdoing this with the highly modified malts that are available these days. But they should also be fine with a single infusion mash.
This said, don't make you mashing more complicated unless you know what is happening at the steps and why you think you should be doing this. There is definitely a difference in acquiring knowledge about the mashing process and actually getting a chance to use this knowledge in your own mashes.
I also have to ask Weyermann (my maltster for German malts) for an average lot analysis of their mats in order to keep the justification for a protein rest.
It looks like as if these days you will have to find a compromise between authentic/historic mash schedules and modern malts. BeeGee once pointed out that some HBSs sell undermodified pilsner malt. This is definately an indication that regular Pilsen malt may not be well suited for some mashed. E.G if you want to do use a decoction mash for flavor, you need to find some rests that you can decoct to. And these days you almost have to eliminate the protein rest.
Kai