Enzymes are denatured with time. Mash thickness, crush, pH and temp determine how quick it takes to denature enzymes. Mash pH is important because A and B-amylase work within a certain pH band. If a brewer treats the brewing water to lower pH to 5.2, Beta favors the pH. The same pH retards Alpha. At 149F in about an hour B amylase is denatured in a thick mash. In two hours at 149F A amylase is denatured. Below 149F starch doesn't gelatinize, limiting enzymatic action. Below 149F, B-amylase only eliminates long chain dexitrins formed and do very little to reduce starch. The starch chain is made up of a reducing end and a non reducing end. B-amylase only does its thing to the non reducing end. It's a molecular bond with water. A-amylase chops up the starch chain creating more non reducing ends. There are branching and debranching enzymes. The enzymes create many non reducing ends. The enzymes are denatured at 140-145F in lower modified malt. They are inverted in high modified malt during kilning, making them useless. Check for conversion in 20 minutes if the iodine color doesn't change, thin down the mash. It will convert quickly. Why screw around after conversion? Mash out to denature enzymes and run it off. The problem with a mash out with infusion method. Starch that gets stuck in the husk or that isn't ground fine enough to gelatinize will burst. The enzymes being denatured by the high heat will do absolutely nothing with the excess starch. The starch ends up down the line, reducing the shelf life and stability of the final product. Add to it a batch sparge, washing the rest of the goop into the boiler. But, who cares when going from boiler to belly in 4 or 5 weeks.
