For a long time now my standard mash incorporates a long (30-45 min) rest at 160 F which usually gives me full conversion after it is done. I have yet to take the time to plot the mash gravity over time. Could you elaborate on your standard mash procedure, please? I'm trying to maximize my conversion efficiency and right now I am stuck at around 92-93%.
My standard mash, which I use for most of my German beers goes like this:
- 63 C (145-146 F) held for 30 – 45 min. This is the maltose rest and its length controls attenuation
- Then heating while stirring
- 70-72 C (158-162 F) held for 30-45 min (sometimes even 60 min). This is the dextrinization rest and it needs to be held until the mash is iodine negative. That may happen after as little as 15-20 min but I’m holding it longer since some literature sources mention head retention and mouthfeel improvements for an extended rest at this temp. The few explanations that I found involve glycoprotedies which are releases into the wort but the enzymes that would be able to degrade them have already been denatured. I haven’t done any experiments regarding this effect yet.
- Then heating and stirring to mash-out at 75-76 C (167 – 169 F)
My malt is milled at about 0.7-0.8 mm (28 – 31 mil). I think my good conversion is helped by the fact that I do stir the mash, mash thin and hold that long rest at 160 F. But mashing with direct heat may not be a viable option for everybody since it does take a little more effort.
Interesting, I think I'll give that a try on my next batch. I know the problem isn't my crush, so it's probably the lack of agitation during the (single infusion) mash and having a second rest at 160F. Two questions: (1) What is your conversion efficiency with this procedure? (2) Do you use a different mash schedule for non-German beer styles?