Interesting German Brewing PDF

It is interesting. I wish there was someway to know how true it is, they seem very pedantic and a take it at their authority with little references. It would be difficult for me to try it without a large investment in equipment, since i have a copper immersion cooler, and a mash tun set up for top sparging.

Also not adding o2 to a lager yeast concerns me.

giraffe said:

It is interesting. I wish there was someway to know how true it is, they seem very pedantic and a take it at their authority with little references. It would be difficult for me to try it without a large investment in equipment, since i have a copper immersion cooler, and a mash tun set up for top sparging.

Also not adding o2 to a lager yeast concerns me.

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Not sure you read that last part right... You add o2 AFTER adding yeast FYI.

Would be interesting to have more details of their methods. What experiments did they conduct to compare outcomes from changing the variables? What assumptions are they actually making? Their comparisons between "normal" homebrewed beer and their magical low O2 brewed beer are a bit hyperbolic, though. I am skeptical the differences are so pronounced. In intervews Charlie Bamforth has stated that all the hot side OCD O2 purging makes a miniscule, if any, difference compared to the effects of O2 pickup during packaging.

If I brewed the same beer and skipped all the hot side O2 putzing and just started from Section 4 would they really be able to taste a difference within the normal lifespan of a typical strength Helles?

Ah, I see it now. Thanks.

I have tried it.. and it's life changing.

Ditto ^^^

Ok im intrigued. One question though, how do you prevent oxidation during the decoction?
Actually two questions, is a stainless immersion chiller sufficient, or what do you recommend for cooling?

giraffe said:

Ok im intrigued. One question though, how do you prevent oxidation during the decoction?
Actually two questions, is a stainless immersion chiller sufficient, or what do you recommend for cooling?

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Decoction causes a lot of O2 unless you can keep the splashing down somehow during transfers. I just do Hochkurz direct heat now.

Yes, stainless steel IC and I just carefully Whirlpool with a spoon being careful not to splash.

I think a reason Germans mash thin so decoction transfers can be pumped in with minimal splashing. Probably also transfer into the bottom or lower part of the tun.

Ugh. I dont have a direct fire-able mash tun. This is getting problematic. Perhaps i should pick up an o2 meter first, do you all have a recommendation for a inexpensive one?

DO meters aren't cheap, maybe you should just try a pre boil and recommended dose of MBS first. Try a hochkurz using boiling water infusions, just be careful when mixing in.

You don't have to follow the document to a T to see a difference. I'm still not there yet, still working on the fermentation phase, need more equipment.

A summary of the main points:

• Hot Side Oxygenation is actually a big deal, but happens so early in the brewing process that homebrewers didn't know how to prevent it.
• Copper increases oxidation, so throw out your copper chillers.
• Grind grain slightly damp so the husks stay intact. Mill immediately before mashing.
• Degas your mash water by boiling it, then add sulfite in fairly large doses (100 mg/l; a Campden tablet is 440mg).
• Chill to mash in temperature.
• Infuse with minimal stirring, by underletting if possible. If your grain floats it's trapping too much air.
• Cover the mash tun during the mash. They advocate a two-rest Hochkurz mash and melanoidin malt rather than decoction.
• Treat sparge water similarly (a bit less sulfite) to mash water, or use no-sparge.
• Expect lower mash pH and higher sulfate due to the sulfite scavenging O2.
• Boil at a high simmer rather than a rolling boil.
• Pitch before oxygenating.
• Keg in a CO2-purged keg before primary is complete. Keep headspace to a minimum and put a pressure relief on the keg. Allow some yeast transfer.
• If you re-keg or bottle purge and allow yeast transfer, consider adding sulfite as well. For bottling the easiest is to krausen and counter-pressure fill. For re-kegging the easiest is – don't.

Did I miss any high points? If you want to get into the details, of course read the paper – it's a quick and easy read, but very very opinionated!

Given all the debate about whether HSA is real, this is an interesting counterpoint to the skeptics. It reinforces my feeling that commercial brewing practice has a very different set of concerns that are either irrelevant to home brewing or (as in this case) pretty difficult to achieve without industrial process control. A few things stand out as easy to do – sulfiting to scavenge oxygen and pitching before aeration come to mind. Others (grinding and doughing in) seem a lot harder.

Aren't sulfites forbidden by Reinheitsgebot, and aren't these guys German? Some of their methods are certainly not used by German commercial brewers.

My opinion of the article is that it is very week from a scientific standpoint. The science world won't accept a paper presenting lots of things stated as "fact" without any supporting data. They don't even present any results of blind triangle testing, not to mention that they appear to have changed countless variables and concluded they are all important, without any indication at attempts to isolate individual variables and rank them.

I'll stick with methods that have better supporting data.

Brew on

So are they recommending using like 5 campden tablets?

giraffe said:

Ugh. I dont have a direct fire-able mash tun. This is getting problematic. Perhaps i should pick up an o2 meter first, do you all have a recommendation for a inexpensive one?

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I use the Extech DO600. A direct fire mash tun is really handy, because I can preboil my water directly in it. I actually brew no-sparge, and use a pump to slowly recirculate the liquid out from under a false bottom back into the top of the mash, but under the liquid level. This is really handy, because it keeps the temperatures even (especially when moving between steps in the Hochkurz mash) and I never have to stir or agitate the mash. I have an inset lid which sits nearly flush to the top of my mash, leaving less than 0.5 liters of airspace. So, it's kind of a pseudo-closed system, and doing no-sparge further decreases my oxygen exposure. I do one (and only one) transfer on the hot side, gently pumping from the mash tun into the boil kettle. I chill with a stainless steel immersion chiller.

jmaessen said:

A summary of the main points:

• Hot Side Oxygenation is actually a big deal, but happens so early in the brewing process that homebrewers didn't know how to prevent it.
• Copper increases oxidation, so throw out your copper chillers.
• Grind grain slightly damp so the husks stay intact. Mill immediately before mashing.
• Degas your mash water by boiling it, then adding sulfite in fairly large doses (100 mg/l; a Campden tablet is 440mg).
• Chill to mash in temperature.
• Infuse with minimal stirring, by underletting if possible. If your grain floats it's trapping too much air.
• Cover the mash tun during the mash. They advocate a two-rest Hochkurz mash and melanoidin malt rather than decoction.
• Treat sparge water similarly (a bit less sulfite) to mash water, or use no-sparge.
• Expect lower mash pH and higher sulfate due to the sulfite scavenging O2.
• Boil at a high simmer rather than a rolling boil.
• Pitch before oxygenating.
• Keg in a CO2-purged keg before primary is complete. Keep headspace to a minimum and put a pressure relief on the keg. Allow some yeast transfer.
• If you re-keg or bottle purge and allow yeast transfer, consider adding sulfite as well. For bottling the easiest is to krausen and counter-pressure fill. For re-kegging the easiest is – don't.

Did I miss any high points? If you want to get into the details, of course read the paper – it's a quick and easy read, but very very opinionated!

Given all the debate about whether HSA is real, this is an interesting counterpoint to the skeptics. It reinforces my feeling that commercial brewing practice has a very different set of concerns that are either irrelevant to home brewing or (as in this case) pretty difficult to achieve without industrial process control. A few things stand out as easy to do – sulfiting to scavenge oxygen and pitching before aeration come to mind. Others (grinding and doughing in) seem a lot harder.

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That's most of it, but we're not suggesting that you use melanoidin malt to "emulate" a decoction or anything like that. I recommend the base recipe, and if you want to add a cherry on top for a subsequent brew, try the melanoidin malt or caramunich. I actually like the caramunich a lot better.

This should have probably been included in the pdf, but when conditioning your malt it's not a bad idea to dose the water in your spray bottle with an itsy bitsy pinch of sulfite powder, especially if you're using tap water with chlorine or chloramines.

doug293cz said:

Aren't sulfites forbidden by Reinheitsgebot, and aren't these guys German? Some of their methods are certainly not used by German commercial brewers.

My opinion of the article is that it is very week from a scientific standpoint. The science world won't accept a paper presenting lots of things stated as "fact" without any supporting data. They don't even present any results of blind triangle testing, not to mention that they appear to have changed countless variables and concluded they are all important, without any indication at attempts to isolate individual variables and rank them.

I'll stick with methods that have better supporting data.

Brew on

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Well, you shouldn't think of this as a research paper because it's not actually presenting any original research. Think of it more like a recipe. We are presenting a methodology for oxygen control during the entire brewing process that is doable at home. Big breweries control oxygen too, but using different methods that would be a lot harder to emulate at home.

The books we cite contain references to dozens of journal and conference papers that have undergone actual peer review processes and corroborate our claims. The science behind HSA is more than 50 years old and widely accepted in the academic brewing community. The laws of physics and chemistry don't magically change just for you because you're a home brewer. It's really only in the home and craft brewing communities where it's disputed, due to some deeply flawed experiments that people have performed in the past which didn't take several things into account:

1) The strike water is already oxygen saturated to about 4-5 ppm before dough-in. Fix states that it only takes a little more than 1 ppm to cause irreversible damage to malt compounds. Furthermore, even if you degassed your brewing water completely, dough-in immediately mixes in another 1-3 ppm, and a further 1-2 ppm diffuse into the mash from the atmosphere every hour. No experiment claiming to "debunk" HSA that I've ever seen has actually measured the dissolved oxygen content at any point in the process with a meter. By the way, you probably shouldn't try to use a DO meter directly in your mash, because they're generally only good up to about 120 degrees F (mine is good up to 122). I typically scoop a sample very gently in a cup and rapidly chill it in an ice bath before taking my readings.

2) HSA isn't just about cardboard flavors. Trans-2-nonenal results from oxidized malt lipids and is often talked about as being the biggest concern with HSA. Interestingly, malt lipids can actually be oxidized without the presence of dissolved oxygen by lipoxygenase enzymes which are naturally present in the malt, but that's a bit of a tangent. Trans-2-nonenal is eventually what causes the cardboard flavor, but there's actually a lot more than just lipids that can oxidize in the mash/boil. Aromatic simple phenols from the malt are the chemical compounds which make fresh malt smell and taste like fresh malt, but upon oxidation they rapidly polymerize (i.e. link up into chains) into polyphenols and tannins, which don't have the "fresh grain" flavors, and instead taste kind of bitter. This is one reason why the wort you normally make tastes so different from the raw malt. The phenols are the things that we're trying to protect. Additionally, everybody knows that melanoidins and many Maillard products are antioxidants (meaning that they readily react with oxygen), but did you know that their flavor changes once they've been oxidized? Case in point, caramel malt tastes completely different in a low-oxygen brewed beer. Rather than tasting cloying and overpowering, the flavor comes across as sweet in a refreshing way, and lends a very unique flavor to the beer that really enhances the malt character. Nowadays, I'm using 5-10% caramel malts in my pale lagers (they still ferment from 1.048 down to 1.009-10, even following a traditional cold fermentation schedule, and end up around 4 SRM!) and even up to 15% in beers like hefeweizen. In fact, all malts come through with far more "clarity" in their flavor and are a lot less muddy with low oxygen brewing. You can read about oxidation of phenols and Maillard products in Fix's book.

3) The oxidation reactions that happen in the mash begin instantly, and reach peak activity within 30 seconds to 2 minutes, and the bulk of the oxidation has already happened after 4 or 5 minutes. You can see plots illustrating this in Kunze's book on page 234, where he has a graph showing oxidation reaction rates with respect to time (measured using chemiluminescence detection) under normal and low oxygen brewing conditions. The low oxygen mash has orders of magnitude less going on in the way of oxidation reactions! Some people have talked about throwing a couple campden tablets into the mash, but that's far too little far too late. The damage has already been done at dough-in!

I also want to mention that the pdf emphasizes that cold side oxygen control is just as important. You really want to keep the dissolved oxygen level in the final package under 0.1 ppm (this is the target that John Kimmich from The Alchemist discusses as well). But did you know that the amount of air it would take to fill a single shot glass, if trapped inside the keg, will raise the dissolved oxygen content of a 5 gallon batch of beer by more than 0.2 ppm? It's really hard to get ALL of the air out of a keg, and we measured that our own racking procedures going from primary into a purged keg picked up between 0.4 and 0.8 ppm! The only method we can currently recommend in good faith is spunding in the keg with active yeast, because the yeast will consume any oxygen picked up and keep the DO level of the beer close to zero.

You're correct that German breweries probably aren't using sulfites in their brewing processes. You can read through "Technology: Brewing and Malting" by Wolfgang Kunze, or look at the Krones catalog on their website, to get an idea of the equipment they're actually using. The German brewhouse has been designed around low-O2 since the 1960s, and was largely driven by Ludwig Narziss' revolutionary research on the topic of oxygen in the brewhouse which earned him a chaired faculty position at TUM Weihenstephan. The Germans are actually using mechanical means to control oxygen at many different steps in the process. Their brewing water is degassed as part of standard water treatment, but rather than pre boiling they typically bubble up a gas like CO2 through the water inside a packed column and under a mild vacuum. I think one of the coolest methods they use is arrays of vibration units in the mash tun, such as the Shakesbeer system produced by Krones. It actually transmits sound waves through the mash, which literally knock the tiny bubbles of dissolved oxygen out of solution. Kunze also highly recommends mashing under a protective blanket of nitrogren gas. There's a lot more to it as well, and you can read about it all (and admire the very detailed pictures and diagrams) in Kunze's book.

By the way, Charlie Bamforth has recently started acknowledging oxidation in the mash and has already published at least one paper on the effects of vitamin C and ascorbate oxidase (a naturally occurring enzyme in malt which catalyzes the oxidation of vitamin C) as one antioxidant strategy for the mash. I'm actually not sold on this method yet over sulfite, because the oxidized form of vitamin C (dehydroascorbic acid) sticks around in the beer and is highly reactive with many other compounds found in beer. Once it scavenges an oxygen molecule, sulfite simply turns into sulfate which is relatively inert in beer, and just about everybody has some sulfate in their brewing water anyway. Charlie talked about this on a recent episode of the beersmith podcast where he was the guest, and also mentioned the color reduction that low oxygen brewing brings.

But above all, I would recommend that you attempt the low oxygen mini-mash test posted here:

http://forum.germanbrewing.net/viewtopic.php?f=49&t=301

It's really easy, doesn't require any special equipment or ingredients (other than the sodium metabisulfite), and takes only about 2 hours. p-values are cool, but seeing (and tasting!) is believing!

We're not out to try and convince the entire homebrewing community to change the way that they brew, and we're certainly not out to sell you books or t-shirts either. This is just information which was the result of a few people working very hard to try and figure out why the Bavarian beers we love so much taste the way they do, and why no home or craft brew has been able to capture that special flavor. This information is freely available to anybody who wants to give it a try, but I admit that it is very involved and not for everybody.

I hope that answers some of your questions.

Nice write up techbrau, explains a lot.

I've seen some people mention the use of a little bit of sugar in your keg to scrub the O2 as well or just going ahead and using the right amount to fully carb if you want to bypass the spunding. I guess there's krausening as well.

techbrau said:

p-values are cool, but seeing (and tasting!) is believing!

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Actually it isn't at all. That's why we have double blind triangle tests!

Here I have a second opportunity this week to tell a favorite story of mine in this regard. About 3 yrs ago I was asked to write a chapter on beer color for a book Charlie Bamforth was doing (the final proof just went out today - hurrah). At right about that time ASC sent me a notice of a webinar in which Charlie was the featured speaker and the subject was beer color. Seemed to me it would be a good idea to watch that webinar and I did. In it he said "we taste with our eyes". I think everybody knows that but I was shortly after that invited to a gathering at which many of the local beer cognoscenti ((pro's, Master judges....) were to be present. I took two growlers containing similar lagers. One was darker than the other. I asked for criticism and comparative comments from several of these people and the distinctions they were able to draw astounded me. How much richer the dark beer was, how the one had more vanilla notes and on and on. One little lady asked if she could try nd upon tasting the two apologetically explained that she really didn't know anything about beer and was just accompanying her boyfriend but that she really couldn't taste any difference at all. I expect that you have figured out what the deal was by now. The emperor had no clothes. It was the same beer in the two growlers with a little Sinamar (I don't think the color difference could have been as much as 5 SRM). When my duplicity was revealed several people were pretty angry. One guy didn't speak to me for over a year and I didn't get invited back.

The point is, of course, that if you want to taste something badly enough, you will. As I said at the outset, this is widely enough appreciated that we use double (yes, even telegraphing of the 'right' answer to the taster can be a problem - look up der Kluge Hans) triangle tests with the triangle part being there to be sure the taster can correctly detect that there even is a difference.

So I think the guys are absolutely right to express the healthy skepticism that they have shown here. The devotees speak of the technique with almost religious fervor and wherever one sees that he is well advised to step back and say "Well let's see." Quotation from the Holy Books is often used in support of hypotheses such as the current one and I note that his is being done here. Kunze's book contains at least one glaring error (which the aforementioned Charlie Bamforth propagated by quoting in a fairly recent paper) and in fact he has very little to say about oxygen exclusion from mash including a statement to the effect that one should not minimize the oxygen content of a mash but rather reduce it.

None of this is to say that I think the thesis is a bad one. To some extent it makes sense. But you really want people to question and challenge and even try to prove you wrong. If you are on solid ground you will be vindicated.

ajdelange said:

Actually it isn't at all. That's why we have double blind triangle tests!

Here I have a second opportunity this week to tell a favorite story of mine in this regard. About 3 yrs ago I was asked to write a chapter on beer color for a book Charlie Bamforth was doing (the final proof just went out today - hurrah). At right about that time ASC sent me a notice of a webinar in which Charlie was the featured speaker and the subject was beer color. Seemed to me it would be a good idea to watch that webinar and I did. In it he said "we taste with our eyes". I think everybody knows that but I was shortly after that invited to a gathering at which many of the local beer cognoscenti ((pro's, Master judges....) were to be present. I took two growlers containing similar lagers. One was darker than the other. I asked for criticism and comparative comments from several of these people and the distinctions they were able to draw astounded me. How much richer the dark beer was, how the one had more vanilla notes and on and on. One little lady asked if she could try nd upon tasting the two apologetically explained that she really didn't know anything about beer and was just accompanying her boyfriend but that she really couldn't taste any difference at all. I expect that you have figured out what the deal was by now. The emperor had no clothes. It was the same beer in the two growlers with a little Sinamar (I don't think the color difference could have been as much as 5 SRM). When my duplicity was revealed several people were pretty angry. One guy didn't speak to me for over a year and I didn't get invited back.

The point is, of course, that if you want to taste something badly enough, you will. As I said at the outset, this is widely enough appreciated that we use double (yes, even telegraphing of the 'right' answer to the taster can be a problem - look up der Kluge Hans) triangle tests with the triangle part being there to be sure the taster can correctly detect that there even is a difference.

So I think the guys are absolutely right to express the healthy skepticism that they have shown here. The devotees speak of the technique with almost religious fervor and wherever one sees that he is well advised to step back and say "Well let's see." Quotation from the Holy Books is often used in support of hypotheses such as the current one and I note that his is being done here. Kunze's book contains at least one glaring error (which the aforementioned Charlie Bamforth propagated by quoting in a fairly recent paper) and in fact he has very little to say about oxygen exclusion from mash including a statement to the effect that one should not minimize the oxygen content of a mash but rather reduce it.

None of this is to say that I think the thesis is a bad one. To some extent it makes sense. But you really want people to question and challenge and even try to prove you wrong. If you are on solid ground you will be vindicated.

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Hi AJ,

You make excellent points all around, and I'm not going to try very hard at all to convince anybody that I'm right because I'd like the people who are so inclined to try it out for themselves.

To that end, I'd really suggest that you try the mini mash test for yourself and have somebody give you a series of 5 or 6 triangle tests with the worts. It will mean a lot more to you than what a panel of strangers says, because it's your own palette being tested.

All I ask of you is that if you do decide to try the mini mash experiment for yourself, you be completely honest with yourself and what you are tasting. Bias works both ways, you know.

I forgot to add, and this is very important, that I was not trying to impugn Kunze or Bamforth either!

ajdelange said:

Actually it isn't at all. That's why we have double blind triangle tests!

Here I have a second opportunity this week to tell a favorite story of mine in this regard. About 3 yrs ago I was asked to write a chapter on beer color for a book Charlie Bamforth was doing (the final proof just went out today - hurrah). At right about that time ASC sent me a notice of a webinar in which Charlie was the featured speaker and the subject was beer color. Seemed to me it would be a good idea to watch that webinar and I did. In it he said "we taste with our eyes". I think everybody knows that but I was shortly after that invited to a gathering at which many of the local beer cognoscenti ((pro's, Master judges....) were to be present. I took two growlers containing similar lagers. One was darker than the other. I asked for criticism and comparative comments from several of these people and the distinctions they were able to draw astounded me. How much richer the dark beer was, how the one had more vanilla notes and on and on. One little lady asked if she could try nd upon tasting the two apologetically explained that she really didn't know anything about beer and was just accompanying her boyfriend but that she really couldn't taste any difference at all. I expect that you have figured out what the deal was by now. The emperor had no clothes. It was the same beer in the two growlers with a little Sinamar (I don't think the color difference could have been as much as 5 SRM). When my duplicity was revealed several people were pretty angry. One guy didn't speak to me for over a year and I didn't get invited back.

The point is, of course, that if you want to taste something badly enough, you will. As I said at the outset, this is widely enough appreciated that we use double (yes, even telegraphing of the 'right' answer to the taster can be a problem - look up der Kluge Hans) triangle tests with the triangle part being there to be sure the taster can correctly detect that there even is a difference.

So I think the guys are absolutely right to express the healthy skepticism that they have shown here. The devotees speak of the technique with almost religious fervor and wherever one sees that he is well advised to step back and say "Well let's see." Quotation from the Holy Books is often used in support of hypotheses such as the current one and I note that his is being done here. Kunze's book contains at least one glaring error (which the aforementioned Charlie Bamforth propagated by quoting in a fairly recent paper) and in fact he has very little to say about oxygen exclusion from mash including a statement to the effect that one should not minimize the oxygen content of a mash but rather reduce it.

None of this is to say that I think the thesis is a bad one. To some extent it makes sense. But you really want people to question and challenge and even try to prove you wrong. If you are on solid ground you will be vindicated.

Click to expand...

Very well put, and rings true with my own feelings.

techbrau said:

To that end, I'd really suggest that you try the mini mash test for yourself....

Click to expand...

I am, actually, pretty much sold on the idea. Ever since I saw Sean Franklin's setup (Roosters) in Harrogate (tells you how long ago that was) with its CO2 flushed Steele's masher and CO2 blanketed mash tun I've been trying to figure out how I might rig something like that for myself. Never got around to it though.

Well I don't know if that paper's full of malarkey or what...pretty sure 19th century German brewers weren't doing any of that.

But I do know that ANYTHING would taste better if being served by:

ajdelange said:

Actually it isn't at all. That's why we have double blind triangle tests!

Here I have a second opportunity this week to tell a favorite story of mine in this regard. About 3 yrs ago I was asked to write a chapter on beer color for a book Charlie Bamforth was doing (the final proof just went out today - hurrah). At right about that time ASC sent me a notice of a webinar in which Charlie was the featured speaker and the subject was beer color. Seemed to me it would be a good idea to watch that webinar and I did. In it he said "we taste with our eyes". I think everybody knows that but I was shortly after that invited to a gathering at which many of the local beer cognoscenti ((pro's, Master judges....) were to be present. I took two growlers containing similar lagers. One was darker than the other. I asked for criticism and comparative comments from several of these people and the distinctions they were able to draw astounded me. How much richer the dark beer was, how the one had more vanilla notes and on and on. One little lady asked if she could try nd upon tasting the two apologetically explained that she really didn't know anything about beer and was just accompanying her boyfriend but that she really couldn't taste any difference at all. I expect that you have figured out what the deal was by now. The emperor had no clothes. It was the same beer in the two growlers with a little Sinamar (I don't think the color difference could have been as much as 5 SRM). When my duplicity was revealed several people were pretty angry. One guy didn't speak to me for over a year and I didn't get invited back.

The point is, of course, that if you want to taste something badly enough, you will. As I said at the outset, this is widely enough appreciated that we use double (yes, even telegraphing of the 'right' answer to the taster can be a problem - look up der Kluge Hans) triangle tests with the triangle part being there to be sure the taster can correctly detect that there even is a difference.

So I think the guys are absolutely right to express the healthy skepticism that they have shown here. The devotees speak of the technique with almost religious fervor and wherever one sees that he is well advised to step back and say "Well let's see." Quotation from the Holy Books is often used in support of hypotheses such as the current one and I note that his is being done here. Kunze's book contains at least one glaring error (which the aforementioned Charlie Bamforth propagated by quoting in a fairly recent paper) and in fact he has very little to say about oxygen exclusion from mash including a statement to the effect that one should not minimize the oxygen content of a mash but rather reduce it.

None of this is to say that I think the thesis is a bad one. To some extent it makes sense. But you really want people to question and challenge and even try to prove you wrong. If you are on solid ground you will be vindicated.

Click to expand...

Thanks AJ. I wanted to reply in a similar vein, but you said it better than I could.

Brew on

techbrau said:

...

To that end, I'd really suggest that you try the mini mash test for yourself and have somebody give you a series of 5 or 6 triangle tests with the worts. It will mean a lot more to you than what a panel of strangers says, because it's your own palette being tested.

...

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Why would I pass judgment on a process based on the taste of the worts? I'm interested in how the beer tastes, and there are a whole lot of chemical reactions that need to happen before the wort is beer. I put very cloudy wort in the kettle and fermenter, but it pours clear out of the keg. I don't judge the appearance of the wort, why would I judge its taste?

Brew on

I'm not sure that I see what the difference is in process if you prevent as much O2 as possible from entering the wort during the mashing process to 'preserve' certain compounds in the wort, then introduce O2 after pitching the yeast. The compounds are still in the wort, the O2 is introduced... Won't the same oxidative processes happen? I know yeast is present, and they'll use the O2 but surely it's not happening nearly instantaneously?

This is something I'd like to see tested prior to changing *any* equipment out.

It actually happens pretty fast. The yeast cells can pretty much clear a wort of a bolus of oxygen in minutes. This doesn't have to be instantaneous. If it is comparable to or faster than the rate at which the relevant wort compound redox reactions take place the beer will be in a more reduced state that it would be otherwise.

I had no idea that the yeast oxygen uptake was so rapid.

Redox reactions are extremely temperature dependent. The same reactions that happen on the scale of hours at 45 degrees F take place within seconds at 150 F.

At 45 F, the speed at which the yeast take up the oxygen is much, much faster than the rate at which oxidation reactions take place.

techbrau said:

Redox reactions are extremely temperature dependent. The same reactions that happen on the scale of hours at 45 degrees F take place within seconds at 150 F.

At 45 F, the speed at which the yeast take up the oxygen is much, much faster than the rate at which oxidation reactions take place.

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At the Craft Brewer's Conference, this past week, I had the chance to discuss the premise of your paper with Burghart Meyer from VLB, Berlin. He didn't fully disagree, but made some important points.

1) Even with deaerated water, free O2 levels in a pumped or decocted mash routinely hit 3 to 5 ppm. This does not correlate to instant malt oxidation, since free O2 has many ingress and egress pathways that are easier than binding with malt.

2) He (and colleagues) believe that the use of Sodium Metabislufite is misplaced and the sodium is likely the cause of the flavor perception. They suggest that the same O2 control with Potassium Metab. or Ascorbic Acid would yield similar measurements, but different flavor profiles. In fact, Bamforth suggests Ascorbic Acid.

3) Your assertion that all sources of copper, iron, zinc and manganese be eliminated is probably a misread of your sources. It's impractical because they are contributed by malt and hops.

So, while they agree that reduction of hotside O2 is beneficial to Hellesbier, they don't think that the extent of your assertions are necessary. Not wrong, just more than required.