Webinar on Hot Side Oxidation

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lupulus
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Fri Sep 22, 2017 12:01 pm

Techbrau wrote:No, not if the malt is sufficiently modified to already have enough FAN.

There's no reason to dough in any lower than 62c if your Kolbach index is above 38 or so.

Doing so is more likely to decrease wort quality than increase it for the following reasons:

1. Excess FAN is actually going to increase wort darkening during the boil and contribute to reduced flavor stability

2. Well-modified malt already has enough FAN for the yeast, and providing them with more than they need will increase fusel alcohol production

3. The additional FAN produced from a low dough in has to come from somewhere, namely from breaking down medium chain, foam positive proteins.

4. Pretty much all oxidative enzymes in the mash (LOX, PPO, peroxidase) are much more active at protein rest temperatures than saccharification temperatures. Actually they're also far more active at beta rest temperatures than alpha, but doughing in high enough to denature them would also denature beta amylase so in a sense a Hochkurz mash is a compromise between fermentabilty and flavor stability

I rarely deviate from this mash:

30 min 64c
30 min 72c
5 min 76c

With this past year's barley crop I get a consistent 37-38 PPG extraction rate, and a 1.048 OG wort will have an attenuation limit of 1.008

If I had some malt and the above mash didn't work well with it, then I would get some better malt :P


Clarkson 1992 (Bamforth) did an interesting study on enzymes during mashing. From my reading at the time, I understood that PPO is destroyed by kilning and peroxidase is still active at 65C. The take home for me was that to neutralize peroxidase one needs to prevent oxygen uptake as the mash-in temperature will not prevent its effect. I am interested on the interpretation of others, maybe I got it wrong. Cheers!
Ich trinke Bier nur an Tagen die mit G enden , und Mittwochs
Techbrau
German Brewing
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Joined: Thu Oct 15, 2015 1:45 pm

Re: Webinar on Hot Side Oxidation

Postby Techbrau » Fri Sep 22, 2017 12:10 pm

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.
If you always do what you've always done, then you'll always get what you've always gotten.
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lupulus
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Fri Sep 22, 2017 3:26 pm

Techbrau wrote: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.


The article is pretty solid methods-wise, did study pilsner malt (and pale ale malt), and Bamforth has done quite a bit of research in the area (not one and done...). Have you seen conflicting evidence?
Ich trinke Bier nur an Tagen die mit G enden , und Mittwochs
Techbrau
German Brewing
Posts: 400
Joined: Thu Oct 15, 2015 1:45 pm

Re: Webinar on Hot Side Oxidation

Postby Techbrau » Fri Sep 22, 2017 4:08 pm

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..." :D 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.
If you always do what you've always done, then you'll always get what you've always gotten.

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