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Base Malt Flavor Map and HSO

Posted: Sat Jun 02, 2018 3:59 pm
by lupulus
The recent podcast by BeerSmith called my attention to the recently published ASBC method to map base malt flavors.
Given the process does not do much to prevent oxidation of the sample, and given it isolates the mash variable quite well, I thought it would be an interesting control to test hot-side oxidation (HSO). The experimental HSO sample to be processed as anaerobically as experimentally possible.
Questions to the group: Has anybody test this already (the method was published last year).
I will do some testing in August/ September this year but I wanted to share with the group as it is something that is relatively easy to do, and can potentially isolate the experimental variable quite well and compare it to a standard method.
I will also post in Facebook, but please keep lenghty responses to the German Brewing Forum, to avoid boring non-geek Facebook members.

- BeerSmith podcast -
- Test details can be found in:
- DraughtLab BaseMalt testing software / download for Android or iPhone
- BeerSmith blog ... bc-method/
(the blog does not have all the information, ie, size of the Thermo/ Growler to standardize the process)

Re: Base Malt Flavor Map and HSO

Posted: Tue Jun 05, 2018 9:05 pm
by Techbrau
Hi Ric,

A while back a bunch of people did something called a "LODO mini-mash" as a way to test the difference (flavor, color) between a regular mash and one that took steps to minimize HSO. A few details here:


I don't think that the mini mash method quite followed the new ASBC guidelines for malt sensory testing, but I think your idea is definitely worth exploring.

A year or two back I did my own little flavor map in which I simultaneously made a dozen or so LODO mini mashes of various malt varieties. I can dig up my notes and post them if there is sufficient interest in that.

Does that ASBC method call for any acidification of the sample? In my tests I adjusted each grist individually to 5.3 pH, because I thought that doing so would allow me to more realistically extrapolate my conclusions to a full size mash.

Re: Base Malt Flavor Map and HSO

Posted: Wed Jun 06, 2018 12:07 pm
by lupulus
Hi Tech,
No, the method does not call for pH adjustment. It does call for distilled water so one can assume a pH of 5.6 to 5.7 for pilsner malt.
The complete method can only be found if downloading the app, clicking on New Description/ Describe Malt/ and then on the flag on top of the screen. BeerSmith provides a good summary but it is not complete.

The method is simple enough and I have 4 flip-top 64 oz growlers so, I may be able to do an ASBC control, a LO non-SMB experimental 1 and a LO SMB experimental 2.

The LO experimental treatment differences will be
- Water to be deareated (preboiled and fast-cooled method)
- Growler to be flushed with CO2 or N2 after filling

The SMB treatment to be as above plus SMB - 33mg/L water

Need to think further how to maximize the effect. Probably, bottle and capping the final product, bubble CO2 through the experimental samples, and letting the 4 hours allowed by the method elapse by testing. Will have my homebrew club participate.

Suggestions from you or others are welcome.

Re: Base Malt Flavor Map and HSO

Posted: Wed Jun 06, 2018 5:58 pm
by Techbrau
That sounds like a reasonable experimental design to me.

One thing I'd probably do, in addition to acidification, is to fill the LO growlers as close to full as you can. The reasoning here is that there really isn't a good way to measure or know whether your inert gas purge of the headspace was sufficient or not.

One indicator that I think you can use to determine whether or not your experiment was sufficiently controlled is wort color. You should see a 1-2 SRM color difference between the regular and full LODO mini mashes. As I am sure you already know, while the literature is quite sparse when it comes to the organoleptic/flavor effects of HSO, the impact that mash oxidation has on wort darkening is widely documented. Completely anecdotally, I have noticed a strong correlation between color reduction and preservation of the LODO "it" malt flavor. Therefore, if there isn't a 1-2 SRM color difference between the mashes, then there probably wasn't a sufficient difference in the degree of mash oxidation between the samples to give rise to a significant flavor difference.

A few more thoughts:

It may be worth repeating an experiment like this under a few different conditions, such as with/without acidification, and using typical tap water vs. mineral-adjusted distilled water. The reason I bring this up is because there are at least two broad oxidative pathways which appear to be involved in mash oxidation:

1) Enzymatic pathways. There are a number of different enzymes found in malt that catalyze redox reactions that will typically be active to varying degrees in the mash. A lot of people talk about LOX, and a significant amount of lab work has tried to study its downstream impact (e.g. on T2N related staling in the finished beer) but I hypothesize that LOX probably isn't the villain when it comes to the flavor and color changes we witness from HSO. Rather, I think that polyphenol oxidase is the primary bogeyman in the mash. If you buy my argument that low molecular weight phenols are responsible for imparting the fresh malt "it" flavor, then the PPO catalyzed oxidation and subsequent polymerization of these low weight phenols into long chain polyphenolics (which themselves turn dark reddish when further oxidized by PPO) goes a long way towards explaining both the flavor loss as well as the color change. The reason I think it would be interesting to test an acidified/non-acidified mash is because PPO is inhibited to a certain degree by low pH. Therefore, it seems that even if you don't take any of the other LODO steps, acidification of the mash down to 5.2ish will partially inhibit PPO and keep the mash in a somewhat more reduced state than it would otherwise be in. I think that this theory is also consistent with the anecdotal reports I've heard from a lot of people that mash acidification results in a brighter wort with better flavor.

2) Metal catalyzed (Fenton) pathways. Iron, copper, and manganese present in the source water, even at extremely low levels (~10 ppb) are one of the primary pathways for dissolved oxygen (which in its normal state cannot easily react with malt compounds) to be turned into superoxide radicals (which will readily react with malt compounds). Almost all tap water has more than enough metal to support this pathway. I hypothesize that the removal of these ions (via RO treatment, use of distilled water, chelation, etc) can inhibit this pathway (but maybe not totally, as malt itself can contribute some of these ions). This may be one component of why people often perceive an increase in wort quality after switching to RO/distilled water from tap water, regardless of whether or not they are brewing LODO.

Given 1) and 2), I'd expect the flavor/color differences to be more dramatic when you don't adjust pH and, also when you use tap water instead of distilled. But this is just food for thought.

Re: Base Malt Flavor Map and HSO

Posted: Fri Jun 08, 2018 7:05 pm
by lupulus
Hi Tech,
Quite a bit of food for thought indeed.
If I am to take the ASBC method of making wort to be the control, I need to decide on a limited number of experimental variables given the ASBC method has many problems to fix to make it lodo.
- I need to avoid the introduction of air
- If I fill all containers to the brim, I am not doing true ASBC, and also, I may not maximize the difference. If I only do it with LODO, it is another treatment.
- If I add SMB, that it another treatment
- If I change the pH, it is another treatment

Given I have 4 thermos, I need to select max 3 experimental treatments.
At the moment I woud do
- ASBC control
- Experimental LODO including boiled water and CO2 flash - I agree there is a risk if I do not fill to the brim, but I am deviating from the method
- Experimental LODO as above but with SMB
- Experimental LODO as above but with SMB and pH 5.2

What would you do differently, given the constraint of making the control a true ASBC process.
I can be convinced to fill all experimental LODOs to the brim, but I think it is too much change. Am I wrong?


Re: Base Malt Flavor Map and HSO

Posted: Tue Jun 26, 2018 12:53 pm
by Techbrau
Hi Ric,

My honest opinion is that HSO is a nonlinear multivariate phenomenon that cannot be holistically characterized by linear univariate experimentation that only changes one variable at a time (unless you are willing to exhaustively perform a very large number of experiments that explore all possible settings of the independent variables)

My suggestion for a small scale experiment would be to try to maximize the difference between the samples by pegging them at reasonable extremes along the HSO axis. Once a difference is established there, higher resolution experiments that investigate the space between those extremes can be done.

You might, for example, first compare the ASBC method as-published against a fully LODO-ized version of it (preboiled water, pH adjusted, SMB/AA/BTB, filled to the brim with no splashing). I imagine you will see a 2 SRM color difference this way and notice significant flavor differences. This observation alone should convince one that there is something significant going on with HSO.

If you have 4 thermos, you could use the third one to eliminate the pH variable by doing an ASBC mash but acidified to 5.2-5.4. I think you will still see a difference between this sample and the full LODO but it may be slightly less dramatic.

The fourth one is up to you - I think it will take many more than four samples anyway to fully characterize what is going on with HSO. I might try to take the ASBC method step by step towards the full LODO and see where the biggest differences arise. Maybe try ASBC + acidification + no headspace in the thermos? That will at least tell you something about the degree of oxidation potential from the initial DO load of the mash water.

Re: Base Malt Flavor Map and HSO

Posted: Tue Jun 26, 2018 1:27 pm
by lupulus
Thanks Tech. Will read in depth and comment later. Cheers!

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