Enzymatic activity during mash-out

Today I brewed the wort for one of my Weissbier experiments (70% light wheat and 30% Pilsner malt). During that brew session I also conducted an experiment to test for enzymatic activity during mash-out. I felt that this was necessary since even some knowledgeable folks (BYO Wizard) seem to disagree with me on that subject.

The used mash schedule was a Hochkurz mash:

45 min at 63C (145F) – Maltose rest

15 min at 70C (158F) – Dextrinization rest

10 min at 76C (169F) – mash-out

The the dextrinization rest was reached with a boiling water infusion and the mash-out was reached with a thin decoction. After 10 min mash-out I filled a small 20 ml vial like the one on the right.

 with a gelatinized wheat starch solution (about 20%) and wort from the mash (about 80%). I did the same with a control where I added water instead of the wort. Both vials were thrown into the mash, where they quickly reached the current mash temperature of 76C. After about 10 min the wort filled vial showed a significantly weaker iodine reaction than the control and at the end of  the ~30 min sparge the wort filled sample was converted. Here is what the iodine test looked like at the end:

 

The control shows a significant reaction between the starch and the iodine whereas the sample doesn't show any reaction between starch and iodine. There is a faint reaction of the dextrines (reddish brown color) visible. The black spot next to the sample was already there.

 As a result of this experiment, I'm convinced that there is still significant enzymatic activity potential during mash out.