German Brewing

PPO may be denatured during kilning of darker malts but I do not believe it is the case for Pilsner malt. Ideally one would dough in at 72c if only beta amylase still survived at those temperatures.

Take a look at Table I and Table II in the Clarkson paper.

It looks to me as if there are three different finished malt varieties being tested. In Table II, the lager malt is shown to have high concentrations of SOD, catalase, peroxidase, and PPO remaining. The ale malt has reduced yet still significant concentrations of SOD and peroxidase, a small amount of catalase, and no PPO.

The malt analyzed in Table I seems to have final enzyme concentrations in-between the lager and ale malts detailed in Table II. My hunch is that it was kilned more aggressively than the lager malt from Table II but less aggressively than the ale malt.

The conclusion I'd draw from those results is that very lightly kilned base malts appear to retain high levels of oxidative enzymes, including PPO. Between Pilsner and Pale Ale malt it seems like a threshold exists at which PPO is denatured, although other oxidative enzymes survive past that point.

Of course, this begs the question of why any brewer would ever bother to brew with lightly kilned malt rather than ale malt when it seems that lager malt is at such an enormous disadvantage when it comes to the oxidative dangers presented by processing. To which my answer would be, "I've never tasted a Helles made with ale malt which was quite so delicious as one made with lager malt..." Heat sufficient to denature PPO is heat sufficient to destroy a great number of other things. As I'm sure we all know by now, Pilsner malt (and beers made with it) is exceptionally fragile.