So this is a very novice question, but I want to get some opinions on maintaining temperature during mash out/ fly sparging. I mash in an insulated cooler so obviously I don't have direct fire. I have no problem getting the mash up to 168-170 before I vourlauf/initiate run off, but the temp generally drops during the run off. My question is, does enzyme activity restart when the temp drops down (say to 158 for an extreme example, usually it's more like 162-165) or are they denatured to the point of no return when they hit 168-170? I do not have problems with flow rate/ channeling/ efficiency, I am more worried about screwing up my fermentable sugar profile that I worked so hard for during the sach rest. Thanks for the help!