Webinar on Hot Side Oxidation

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lupulus
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Thu Sep 14, 2017 5:22 pm

Big Monk wrote:Just as good as the first time I read it. This should have more visibility. Well done.

Thanks Monk !!
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wobdee
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Re: Webinar on Hot Side Oxidation

Postby wobdee » Thu Sep 14, 2017 5:34 pm

Well done Lupulus! Question, you mention dough in temps due to LOX should be 64c, how critical is this? Doesn't the oxygen scavangers help with this so we can mash in lower temps and maintain optimum Beta?
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Thu Sep 14, 2017 5:49 pm

Ancient Abbey wrote:Darn, they didn't have time for my questions :)
While darker beers have measurably more antioxidants, more redox potential and are generally considered more stabile, does oxidizing those dark malts compounds change their flavor? Do you believe HSO still negatively affects dark malt flavors?
Great job, btw!

Per the Wurzbacher Weihenstephan dissertation (2011), darker malts oxidize faster than pilsner malt. I have not seen research on what is being oxidized, but my guess is that it is not fatty acids, leading to nonenal (Wurzbacher did chemoluminiscence which shows oxidation overall).
I have not seen much improvement in my dunkel with HSO prevention, but it was a very good recipe from a great Munich brewer, I have always been anal on the cold side, and I was not doing a lot of splashing to begin with...
I know this is not the answer you were looking for.
Thoughts...

BTW mostly unrelated - I need to read Wurzbacher in better detail, but the big oxidation at mash-in may result from not pre-boiling the water. If you do not pre-boil and do not flush the mash tun with nitrogen there is likely to be a lot of reactive oxygen at mash-in.
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lupulus
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Thu Sep 14, 2017 5:59 pm

wobdee wrote:Well done Lupulus! Question, you mention dough in temps due to LOX should be 64c, how critical is this? Doesn't the oxygen scavangers help with this so we can mash in lower temps and maintain optimum Beta?


For Künze it is very important, for Narziss, not so much.
If you wish to maximize the effect, I would suggest mashing at 64C and 5.2pH to ensure gelatinization, and then let the temperature drop slowly to 62-61C to preserve as much beta as possible. This is only applicable to when you want to achieve the lowest possible FG.
Preboil or another method to get rid of the initial O2 is a must.
Scavengers should help but go low. I am at 600g sulfite and 600mg AA for 30L water and 1L of sauergut with 1.5g of tannins.

NOTE - There are brewers in this forum (you know who they are) that know at least as much, and most likely more than I do. Many of the things I do, I learnt from them :-)
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Techbrau
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Re: Webinar on Hot Side Oxidation

Postby Techbrau » Thu Sep 14, 2017 9:11 pm

lupulus wrote:
Ancient Abbey wrote:Darn, they didn't have time for my questions :)
While darker beers have measurably more antioxidants, more redox potential and are generally considered more stabile, does oxidizing those dark malts compounds change their flavor? Do you believe HSO still negatively affects dark malt flavors?
Great job, btw!

Per the Wurzbacher Weihenstephan dissertation (2011), darker malts oxidize faster than pilsner malt. I have not seen research on what is being oxidized, but my guess is that it is not fatty acids, leading to nonenal (Wurzbacher did chemoluminiscence which shows oxidation overall).
I have not seen much improvement in my dunkel with HSO prevention, but it was a very good recipe from a great Munich brewer, I have always been anal on the cold side, and I was not doing a lot of splashing to begin with...
I know this is not the answer you were looking for.


As far as dark base malt (i.e. Munich malt) goes, I have noticed that reducing HSO results in a richer, clearer, and less muddy Munich malt flavor.

However...

You may have also noticed that low oxygen beers brewed with large amounts of Munich malt tend to develop soy sauce off-flavors down the road, much moreso than dark beers brewed with ample HSO. Most commercial German dunkels and doppelbocks imported to the USA already have developed this flavor by the time they hit the store shelves.

I did some looking into the chemistry behind the flavor of soy sauce (this is a good overview: http://pubs.acs.org/doi/abs/10.1021/jf0709092), and it appears that many of the compounds responsible for the soy sauce flavor are volatile aldehydes that can be formed via oxidation of higher alcohols.

How does that oxidation of higher alcohols happen in beer? Well this paper found that Maillard reaction products, specifically melanoidins, act as oxidizers for higher alcohols in beer, forming these volatile aldehydes: https://www.researchgate.net/publicatio ... ns_in_beer

The first kicker is that this oxidation doesn't require molecular oxygen to take place. The melanoidins themselves are stealing elections from the alcohols.

Now for the real kicker: it is primarily the low molecular weight melanoidins that are acting as oxidizers, as opposed to higher molecular weight melanoidins. Why is that important? Because in nearly the same way that low molecular weight phenolics are oxidized in the mash into quinones and then polymerize into polyphenols, low weight melanoidins, upon oxidation, will polymerize into high weight melanoidins.

Low weight melanoidins, in their reduced state, are often said to have a "finer" flavor than high weight melanoidins, which are purported to taste duller overall.

The summary of the little theory I've put together is:

    Dark beers which experience significant HSO have the majority of their low weight melanoidins oxidized and polymerized into high weight melanoidins. This results in a duller overall malt flavor, but with less of a tendency to develop the soy sauce off flavors over time.

    Dark beers brewed low oxygen have more low weight melanoidins kept intact, resulting in a finer malt flavor. However, over time, these low weight melanoidins will oxidize higher alcohols produced during fermentation into volatile aldehydes which impart a soy sauce aroma and flavor to the beer. This oxidation reaction does not require molecular oxygen to take place and therefore, no matter how good your cold side technique is, there is little you can do to stop it (which explains why even the best commercial Bavarian dark lagers turn to soy sauce by the time they reach the shores of the USA).

The paper I linked to above claims that the reaction between melanoidins and higher alcohols happens faster at higher temperatures and lower pH values. Presumably, having less higher alcohols around in general means that you are going to develop fewer of the soy sauce aldehydes. As far as I can see, the best way we have right now to prevent low oxygen dark beers from turning into kegs full of soy sauce is to take measures to ensure a final beer pH as high as possible (but no higher than 4.5), minimize the amount of higher alcohols formed, and keep them as cold as possible.

Cold fermented beers tend to have lower amounts of fusel alcohols and a higher final beer pH, so that's probably a best practice. However you are never going to be able to ferment any beer with zero higher alcohols, so it seems to me that every dark beer is ultimately doomed, at least after several months. So drink them fresh :lol:
If you always do what you've always done, then you'll always get what you've always gotten.
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Ancient Abbey
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Re: Webinar on Hot Side Oxidation

Postby Ancient Abbey » Thu Sep 14, 2017 10:07 pm

Indeed. I suspect that's why German bocks and doppelbocks tend to be lower in alcohol than American versions.
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Techbrau
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Re: Webinar on Hot Side Oxidation

Postby Techbrau » Thu Sep 14, 2017 11:18 pm

I should also mention that the offending melanoidins are destroyed in highly roasted malt like carafa. So roasted malt doesn't have the tendency to create soy sauce flavors - the worst offenders are Munich malts and melanoidin malts.

By my reckoning, the most flavor-stable malts appear to be pilsner malt, caramel malts, and roasted malt.

Not that any of this is a huge deal unless you are planning on letting beer sit around for 4+ months. Personally I like to start drinking my lagers at the 3 week mark (5-7 days primary, 5-7 days spunding, then a week or so of sitting cold).
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lupulus
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Fri Sep 15, 2017 12:49 pm

Thanks Tech !!
A very interesting hypothesis.
A keg of soy sauce is very appealing, personally. Need to learn how to make a keg of sashimi and another of wasabi and my life will be set :-)
I am a fan of umami (soy sauce) flavor in some beers, notably old ale, quads and weizenbock; have not had any aged dopplebocks yet. I have not noticed the umami flavor in a just finished keg of dunkel (8 months old) but I did notice it (only) recently in a keg of dopplebock that is 9 months old. I do like how the dopplebock is evolving so I will monitor the evolution.
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wobdee
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Re: Webinar on Hot Side Oxidation

Postby wobdee » Tue Sep 19, 2017 10:26 am

lupulus wrote:
Ancient Abbey wrote:Darn, they didn't have time for my questions :)
While darker beers have measurably more antioxidants, more redox potential and are generally considered more stabile, does oxidizing those dark malts compounds change their flavor? Do you believe HSO still negatively affects dark malt flavors?
Great job, btw!

Per the Wurzbacher Weihenstephan dissertation (2011), darker malts oxidize faster than pilsner malt. I have not seen research on what is being oxidized, but my guess is that it is not fatty acids, leading to nonenal (Wurzbacher did chemoluminiscence which shows oxidation overall).
I have not seen much improvement in my dunkel with HSO prevention, but it was a very good recipe from a great Munich brewer, I have always been anal on the cold side, and I was not doing a lot of splashing to begin with...
I know this is not the answer you were looking for.
Thoughts...

BTW mostly unrelated - I need to read Wurzbacher in better detail, but the big oxidation at mash-in may result from not pre-boiling the water. If you do not pre-boil and do not flush the mash tun with nitrogen there is likely to be a lot of reactive oxygen at mash-in.


Care to share that Dunkel recipe?
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lupulus
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Re: Webinar on Hot Side Oxidation

Postby lupulus » Tue Sep 19, 2017 11:07 am

Recipe as provided. I adapted it to my system.

for 30 L
5 kg Munich Malt
1 kg Pilsner Malt
0,3 kg Weizenmalz (hell)
0,2 kg Caradunkel (120 EBC)
0,15 kg Röstmalz - add to 200ml of water at pH 5,4 and let sit for 12 hours, then filter through a coffee filter.

Strike water 20 L = Munich tap water adjusted to mash pH of 5,3 using 10 ml of a 33% CaCl liquid solution and 13 ml of 80% lactic acid
Sparge water 25L adjusted to pH of 6,1 using 6 ml of 80% lactic acid

Step Mash
52° for 10 min
63° for 30 min
72° for 30 min
78° for mash out, no rest

collect 37 Liters of 14°P wort and boil for 60 minutes

Hops - all Hallertauer Perle 8,9% alpha
10 g first wort hopping
22 g at 30 minutes after start of boil
25 g at 5 min before flame out
19 IBU

starting gravity 16°P

Yeast from Schweiger brewery
pitch at 7°C
ferment at 8,0 - 8,5°C until gravity is 4,0 - 4,5°P (about 7 days)
then raise temp to 10°C until gravity is 3,5°P (about 2 days) then transfer to keg
(ending final gravity will be 3,0°P)
after racking, hold beer at 14°C for one week, then drop to 0°C
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