Low Oxygen Brewing

In the past weeks two of my followers have pointed me to a paper released by the folks from the German Brewing Forum. That paper talks about low oxygen brewing and how very low oxygen levels (so low that even very detail oriented brewers will have to change their brewing technique to achieve them) are responsible for what we have been calling the Elusive German Flavor in beer. That delicate malt flavor with a subtle background of fresh hops.

I myself have not been able to test any of this but am very intrigued to do so after reading through the paper. The main points are that one needs to deaerate the strike and mash sparge water, use sodium metabisulfite as an additional scrubbing agent and be very careful with doughing and any oxygen uptake later during the brewing process. A DO (Dissolved Oxygen) meter helps with keeping track of the O2 levels throughout the process.

If you think this is the HSA (Hot Side Aeration) discussion all over again, you are somewhat right with the caveat that there is new evidence and a new theory. This theory postulates that the current standard home and craft brewing process already allows for enough oxidation that additional splashing of the wort does not do any noticeable change. As a result HSA experiments have shown inconclusive results so far.

I have heard that this started to spark controversy and I can see that. If the authors are correct, and many seem to have been able to repeat the results, brewers will have to take a closer look at their brewing process and possibly equipment if they want to achieve these results. But keep in mind that not all types of beers are expected to benefit from this. There are many excellent beers, especially craft beers around the world, that are brewed in conventional brewhouses without a low oxygen process.  It’s more along the lines of decoction where an more elaborate brewing process is used for some beers to achieve the desired flavor profile.

At this point we have something new to try and to look into and need to see how this develops over time. Especially as these beers are showing up in competitions and we can see less biased results.

An anecdotal observation that supports this is that craft brewed beers in Germany (usually brew pubs) lack that delicate flavor that many commercially brewed beers in Germany have. Those commercially brewed beers are more likely brewed in a low-oxygen brewhouse.

Here is a link to the paper: On Brewing Bavarian Helles: Adapting to Low Oxygen Brewing

25 thoughts on “Low Oxygen Brewing

  1. John Palmer’s book has the sodium metabisulfite used to remove Chlorine. I had wondered why RO was used to start with. Tap water would suffice. You could safely dechlorinate by using charcoal filters, citrus fruit slices over some hours and 20 minutes of boiling. I just decrease my Chlorine by using small amounts of city water with distilled water.
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    • This paper was not really about chlorine in brewing water and its removal. Chlorine was mentioned as SMB may also be used by some brewers to remove chlorine. RO water was likely used because many brewers use it to build low alkaline water for brewing lighter beers.

  2. Right, this is about using it to further scavenge oxygen from the mash and wort. Other (and perhaps more ideal) methods include degassing columns CO2 washing, etc. See Kunze, p89 for example.

  3. This method really opened my eyes. It makes sense, oxygen spoils just about everything. The malt flavors really pop, Cara malts are less cloying and candy like. Hop flavor and aroma are enhanced as well.

  4. They seem to be putting the cart before the horse for some of the examples of why some of the devices in brew houses are made.

    • I assume you are talking about the ShakesBeer device. Yes, that’s meant primarily for something else. But the lower DO effect is a nice side effect that’s advertised. I don’t think emulating that will greatly simplify low DO brewing. Getting the air out of crushed grain is a tough problem.

      • There’s another issue here that we should have mentioned in the paper, but large breweries actually need to worry far less about oxygen ingress than homebrewers because of the square-cube law. As you increase the diameter of the mash tun (or boiler, etc) linearly, you also linearly decrease its surface area to volume ratio. Therefore oxygen pickup in large systems from the atmosphere is considerably less than in a homebrew system.

  5. Kai,
    I have thought in the years past that anything significant worth knowing about German brewing techniques was documented on your site. Since reading the linked paper, I can only now suspect not! I hope you find some interest and motivation to investigate this further – myself, I have ordered a DO meter and vacuum pump in order to investigate these effects.
    Thanks for bringing it to everyone’s attention.

    • Zig,

      Thanks for your trust in my site, but ther’s a lot more to brewing science than whats there. I had been focusing on what matters for home brewers. The issue of low oxygen has been well documented in the literature but until now I thought that homebrewers would not be able to observe the effects of a low oxygen brewhouse.

  6. Thanks for your thoughts on this, really interesting.

    I wonder if you also had any opinions on whether half-measures would be any use? Simply put, I don’t have the equipment to boil and chill my mash water, so would it be any use trying to employ some of the other methods? The article seems to imply not, that the oxygen introduce at the start would already have completed it’s terrible work…

    • I plan to do a mini mash experiment first where I can better control the process. But I am worried about the additional equipment cost that would be needed. I don’t want to buy or replace anything that’s not necessary at the end. I would think that this concern is shared by many.


  7. I’m very glad this information came to light when it did, as I am brewing a Märzen this week. I intend on following the recommendations made in their report. Have SMB on the way in the post, and enough freshly propagated WLP833 for 25 million per ml pitch rate.
    I mash in an esky, and my HLT has a ball valve tap on it, so filling gently from below is possible.
    Kai, here’s a question you may be able to help me with. Would flooding the grist from below with CO2 prior to mashing in, via the copper manifold in the bottom of my mash tun, be an effective way of scrubbing oxygen from the grist? Further to that question, would blanketing the headspace of the mash with CO2 be advisable? My concern is CO2 becoming soluble and the issue of carbonic acid affecting mash PH in an undesirable way (if at all?). I am using RO water. My understanding of the affects of CO2 on mash at these temperatures is beyond my understanding of chemistry. If there are no issues with this idea though, it would be a good way to further ensure protection from O2.

    • Something I forgot to mention in my first post. I have a copper wort chiller (which in future, based on this information I will change for stainless steel). My intention is to chill mash water in a cold water bath for mash in. Chilling the wort after the boil however, is more problematic. This theory suggests the oxide layer on the copper will leach oxygen into the brew…… Perhaps bathing the wort chiller in hot water dosed with MBS to absorb as much as possible? What do you think?

      • Sorry typo. I meant bathing the copper wort chiller in hot water dosed with SMB*, prior to immersing in hot wort. Also sorry about the long post!

      • I don’t know enough about the copper oxide’s ability to oxidize the wort. That’s an aspect where I have to see how it goes. I have a copper plate chiller and don’t feel like replacing it just because of this.

        • From Kunze pg. 242
          “Oxidation processes occur more rapidly in copper vessels” Its not to say you CAN’T use copper. but you WILL have a higher DO ppm with it.

        • Hi Kai,

          Copper is a tricky subject here because it depends on how much is used, when and where in the process, and how much oxide is on the surface. The oxide layer is quite soluable in wort (unlike the oxide layer on stainless steel) and can be a source of both oxygen and copper ions. The problem here is largely with the copper ions (as well as other metals like iron and manganese) because they effectively act as catalysts for oxidation reactions via Fenton-like processes. You can strip the oxide layer with an acid before use (star San would probably work) and that should help, but even then you will probably still get some copper leeching. Kunze is quite explicit about copper vessels accelerating oxidation reactions, and nowadays just about all of the copper kettles in Germany are actually lined with stainless steel if you look inside.

          Now, all of that said, our group has had Lodo beers that were chilled with copper ICs go on to win best of show (and runner up best of show) at BJCP comps, so I do not believe that a copper chiller will ruin the beer. I would probably try to eliminate copper from the mash tun and boil kettle, though. In theory a stainless chiller would be less risky and may produce a beer with more of the low oxygen flavor, but I believe it is one of the less critical parts of the process. Get everything else dialed in before you worry about the chiller.

          You’ll soon get to taste the Lodo wort flavor when you try the mini mash. Brewing becomes a game of keeping that flavor in the wort/beer. Taste a small sample of your knockout wort chilled in an ice bath in a cup next to wort that has gone through your chiller; if you notice flavor loss, then you may have a problem. If not, then you’re probably ok.

          The cold side of the process is just as important (perhaps more so) than the hot side but I think it’s been largely overshadowed in the discussion across the web because the HSA aspect is more controversial. It’s critical to keep DO in the serving vessel as close to zero as possible. Normal CO2 purging of a keg before racking is highly variable and you have no way of knowing how well you did until it’s too late and you can take a DO measurement. We tended to pick up between 0.4 and 0.8 ppm DO this way, which is enough to make the malt and hop flavors fade in 1-4 weeks. You really want to be under 0.1 ppm. Thus far, the best way we’ve found of doing this is filling be lagering vessel nearly to the brim and spunding with 1-2% remaining extract.

          • Thanks Dave.

            The plate chiller was enough of an investment that I don’t want to get rid of it. But I could use some StarSan before use to mitigate the copper issue.

            I haven’t tried the mini mash experiment yet. Too busy.


    • Yes, I thick that flooding the crushed grain with CO2 can help by displacing most of the oxygen. I don’t think it will mess much with the water chemistry as the formed acid is a weak buffer unless there is some calcium carbonate that’s being dissolved.

      In the end this is up to experimentation. The CO2 may not stay on top of the wort, for example, as it warms up and rises.


  8. Sounds like it is worth trying OD brewing. I have altered my setup to reduce oxygen as much as possible, but was wondering about the yeast recommendation for the Helles recipe. It does not recommend a dry yeast, is that because re-hydrated dry yeast do not scavenge as much oxygen as liquid yeast, or is it just a flavor thing to suit the recipe in question?

  9. Hello, I’m just curious to know if you’ve done any experimenting since the early summer? I’ve just recently stumbled across this paper and am both intrigued and skeptical. I’m intrigued because I like the theory (ie, that the effects of HSA most craft beer suffers from subtle detriments due to early oxidation of the mash, so much so that we have few examples of “oxygen free” beer to reference them against). I’m skeptical because–if the proposed mechanism of oxidation is correct–I doubt that it’s actually possible for most home-brewers to keep O2 contact to a minimum during the whole hot side process. Beyond that, I’m also skeptical that the relatively small amount of SMB (relative to the mass of the malt) will have the power to out compete any potential malt oxidization targets for any O2 that may be introduced–seems a little like homeopathy.

    That said, if you tell me that you’ve experimented with it and think it might work, I’d be ready to throw my skepticism to the winds and dive into crazy process of trying to keep my mash oxygen free!


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