For all the all-grain brewers more experienced than me, I have a question. How critical is the temp of the sparge water? As I understand it the sparge serves several functions. Rinsing out as much of the fermentables as possible, fixing the flavor profile by killing off the amylase enzyme among others. Most recipes I've seen call for a sparge temp around 168 F, as well as my BeerSmith derived recipes. Basically I'm asking what happens if your temp is over 168 F, what happens to the sweet wort (chemically speaking) ?