Mash rest times

[Brewstilla]

I've been mashing the following successfully, but in an attempt to streamlining my cook days, wondering if the rest times may be overkill that could be shortened. 

300 gallon mash

250 gal water, 250#rye, 250#wheat

pH to 5.5 add 40ml Bioglucanase and 200ml Hitempase - hold at 120 for 30 min

heat to 180 - hold for 60 min

cool to 140, pH to 5.5 add 40ml Bioglucanase and 200ml amylo300 - hold for 60 min

 

In my past brewering career I played with saccharification rest times, all the way from a full hour to as short as beginning vorlauf as soon as I was mashed in and began runoff.  I settled on 30 min as I got the same conversion as 60 min - rests shorter than 30 min resulted in less conversion, but not nearly as bad as you would think being as modern malts are so well modified.  So I got to thinking that I could potentially shorten my 140 rest and maybe my 180. Thoughts? 

[Tom Lenerz]

We do just hitempase, no bio up front with no hold until 185 for 20 minutes. Add bio, amylo and malt at 145 and hold 30, cool to fermentation. Works well for us, we see between 4.3 and 4.8 PGs of hearts per bushel on a single pass run.

[adamOVD]

I use the same enzymes and the same rest stages on a also about 2# per gallon 80% Wheat whiskey. I have a Bain Marie still so my heat times are probably slower. I only rest at 15 min at 120. When the mash temp reaches 165 I start my cook time, and turn off the heat at 180, which is usually about 20 minutes later. My last rest is at 130-140F and 5.3 pH(not sure where I got a different number than you) for 30 min. I figure even though the grains aren't as well modified as malt, the enzymes remain active during the fermentation. 

My final gravity is .1-.2 Brix, but I also use some specialty malts, and I'm not sure they would ever finish out 100%. You could always try a shorter rest, and see if your final gravity goes up at all. I'd be interested in the results. I tried a few changes in my rests when developing the recipe, but didn't notice much of a difference. I was changing a couple of things at once though, and still figuring things out, so my numbers aren't very reliable.