Low Oxygen Brewing

For those of you who are members of AHA there is a presentation that you can watch/listen to on the AHA website. I posted the below in another thread.

It is a fact that HSA occurs during the brewing process. The fundamental question is: Does HSA impacts the flavor qualities of the resulting beer. If you are an AHA member I would recommend that you watch/listen to the presentation linked in the below message I posted previously.

Cheers!

On September 13, 2017 there was an AHA online presentation by Ricardo Fritzsche entitled Hot Side Oxidation (HSO) – Fact or Fiction?

For those of you who are AHA members you can watch an archived version of this presentation:

https://www.homebrewersassociation.org/archived-zymurgy-live/hot-side-oxidation-fact-fiction/

IMO Ricardo did a very good job putting this presentation together and discussing the topic of Hot Side Oxidation (HSO)/Hot Side Aeration (HSA).

As Ricardo mentioned during his presentation there is no doubt that HSO/HSA occurs during the early portions of the brewing process (e.g., mashing, transfer of the mash, etc.) but the fundamental question is whether this HSO/HSA genuinely impacts the flavor qualities of the resulting beer.

There has been some scientific studies performed for the case of Pale Lager beers and the data of these scientific studies were part of the presentation. A number of brewing scientists were referenced including Professor Dr. L. Narziss, Dr. Charlie Bamforth, Wolfgang Kunze,..

I have read a number of papers authored by Professor Dr. L. Narziss but I have read more papers from Dr. Charlie Bamforth and listened/watched numerous podcast discussions by him (e.g., Beersmith Podcasts). One paper from Dr. Charlie Bamforth that I would recommend is:

http://onlinelibrary.wiley.com/doi/10.1002/j.2050-0416.2011.tb00496.x/epdf

I would encourage those of you who are members of the AHA to watch the archived presentation and decide for yourself whether HSO/HSA should be a concern for you in your homebrewing and whether implementing LODO (Low Dissolved Oxygen) techniques are worth the effort.

From my perspective some of the takeaway messages of this presentation are:

· All of the scientific data that has been obtained is for the case of Pale Lager beers. As Ricardo Fritzsche made mention a number of times during his presentation this data does not apply to non-Pale Lager beers (e.g., Ales).

· There is disagreement among the various brewing scientists as to whether HSO/HSA is a genuine concern for impacting beer flavor qualities.

· I have the most familiarity with Dr. Charlie Bamforth who has a Ph.D. in Chemistry and he has been a brewing scientist for many decades (first in the beer industry but since 1999 he has been at UC Davis and is the head of the Brewing Science program). His thoughts on HSO/HSA were summarized on page 40 of Ricardo’s presentation: “If the effect exists, it is small” and “Recommends that flavor stability be measured organoleptically”.

Maybe in the future some brewing scientist will study the effects of HSO/HSA on beers such as ales and measure flavor stability impacts organoleptically.

Cheers!

 

I think it holds some water, but the strength of what you can read into it is limited. Firstly it's about a limited set of procedures, which seem representative of what normal cautious homebrewers would do to mitigate HSA but which LODO advocates would say go nowhere near far enough. Secondly it's for one recipe under one set of circumstances. Thirdly it compares relatively fresh beer rather than looking at long-term stability. And fourthly as has been pointed out it's a smallish sample size.

On the other hand, even with a small sample I'd expect them to be able to pick up a sufficiently obvious difference, so it seems fair to say that for this sort of recipe, with this process, drunk reasonably fresh, the difference that normal HSA mitigation procedures will make is probably going to be subtle at best. Which is different from saying that detectable effects of HSA are definitely a myth, but it's still a data point.

 

Another way to discuss this is from another angle: where is the proof that HSA will impact the flavor qualities of my homebrewed beers?

Cheers!

 

Yup.

 

Taste thresholds for each compound that can be tasted do vary among individuals. Regarding melanoidins though...I'm probably as guilty as anyone for being sloppy with maillard product terminology, but melanoidins as a class of compounds are flavorless. There are, however, other maillard reaction products (other than melanoidins, that is) that do have flavor. I blame Weyermann (or whoever it was) for naming a malt "Melanoidin Malt." It would have been better to name it Maillard Reaction Product Malt, but that doesn't have quite the same ring to it. That, plus the fact that every kilned malt (not just "melanoidin malt") has some melanoidins and other maillard reaction products.

DO, AFAIK, cannot be tasted. The problem with DO is that it oxidizes other stuff, and the oxidized compounds can be tasted. The fallacy that HSA can't cause oxidation because the boil eventually drives off O2 ignores the fact that oxidation begins as soon as there is O2 available.

 

Dr. Charlie Bamforth wrote the paper of: Bamforth, Charley W. "A Critical Control Point Analysis for Flavor Stability of Beer." MBAA TQ1.2 (2004): 97-103. Web.

From the abstract of that technical article:

“Furthermore, yeast is a powerful reducing agent that can eliminate carbonyls and, therefore, oxidation upstream may be of less significance than that downstream.”

So while oxidative compounds can be created via HSA the yeast has the ability to ‘clean up’ those compounds during fermentation. The net result is those oxidative compounds no longer exist in the finished beer.

Cheers!

 

There is a lot of 'stuff' written out there.

I choose to read (and listen) to what Dr. Charlie Bamforth states on the topic of HSA.

Feel free to 'listen' to that other 'stuff'.

Cheers!

 

Do you think yeast make transport mechanisms for every possible oxidized compound in wort, so that they can bring them all into the cell and strip their carbonyl group bonds?

 

I'll send an e-mail to Charlie and get back to you.

 

Getting to the "truth" is a challenging avocation.

My recommendation is to get to the facts.

Cheers!

P.S. If you are a member of AHA I would encourage you to watch the archived presentation I referenced above.

 

It would be great to hear what he has to say about it. Perhaps you could also ask him about limiting factors (or lack thereof) in the reactions. e.g. at what point do the yeast stop processing oxidize compounds? I assume they're not doing it out of some desire to improve our beer.

 

Really appreciate this thread and the civil, yet adamant, pursuit of truth to make better beer. Cheers guys.

 

I believe the answer is that the characteristic "low-oxygen" flavor can be found in Weihenstephaner, Guinness, and Budweiser. Link (PDF) here.

Edited to add: Kirin, too.

 

This is the BA I enjoy. Nobody has anything to sell or some sky is falling scenario. Just super geeks in our element.

My opinion of limited value usually gets back to the art of brewing. World class beers have been made for centuries, are being made today and will continue to be made in the future. A DO meter is a nice luxury and an understanding of the chemical reactions that occur is very useful, but brewers are still mostly janitors for the yeast. That's not going to change.

HSA was not even a topic until relatively recently. It may even turn out to be beneficial in certain circumstances.
Cheers.

 

I think the consensus opinions about the importance (or lack thereof) of HSA have swung slowly back and forth over time. I'm pretty sure discussions on the pro boards go back at least 15 years.