Bilsch
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Those are pretty strong words, what say we go take a peek into Kunze and see what he has to say about all this.
Why don’t we start with the trifecta. Sure I’ll give you that oxygen scavengers for the mash aren’t mentioned in Kunze (by the way we never said they were) because macros have no need of them due to their scale. If I had a 500 hectoliter tun I wouldn’t worry about oxygen uptake during the mash either. The square-cube law says as you increase the size of the container you also decrease its surface area to volume ratio. As home brewers our small volume wide mouth kettles have the highest surface area to volume comparatively so if one wants to brew equivalent beers to the macros we need some kind of help in reducing contact with air in the hot side or removing what O2 manages to get in. Metabisulfite and ascorbic acid are well known to mop up dissolved oxygen and are used sometimes in the packaging process so it seemed reasonable to employ these same tools in the mash.
Many commercial tuns have enclosed tops with sealing access doors whereas we homebrewers generally have open top kettles with a lot of open area. Therefore a mashcap is a simple but effective way to reduce the surface area of the wort and a logical low cost approximation of what the commercial brewers do with their expensive equipment. Certainly you won’t find any mention of mashcaps in the professional literature but it solves a problem only the small scale brewer has. Does that invalidate our process because a mashcap is just a hack to simulate a more sealed system? Is this, as you say, an intellectually dishonest, interpretation and execution of the oxidation problems outlined in Kunze? I guess each reader here will have to make their own judgment on that. In that same vein, you won’t find anything about RIMS, HERMS or even the venerable cooler mashtun in these books since these things are also clever homebrew hacks that the small brewers have come up with to approximate the processes of the big guys.
Lets move on to the issue of HSA. Maybe you and I have a different edition of Technology Brewing and Malting because in my copy, Kunze is very specific about avoiding oxygen on the hotside. For instance in chapter 3, Wort Production, where he first makes mention to avoid staling by beginning in the mashing process, “It is therefore desirable to stop the effect of oxidation from the start." Or how about section 4.6.4.2 Factors Encouraging Flavor Stability, where the author makes quite a list, of which I have listed below the ones most pertinent to this discussion.
During mashing
- Particularly avoid addition of oxygen during mashing in.
- Low oxygen mashing in and mashing with a high mashing in temperature.
- Gentle transportation of mash, avoiding shear forces.
- Keep oxygen away while mashing, if necessary pump in nitrogen.
- Mashing from underneath, low oxygen working method. (wait, what’s this he is saying?)
- No narrow elbows in the piping, no entrance of air.
- Mash storage into the lautering vessel from below. (kind of sounds like underletting, no?)
And he goes on in the next part about avoiding oxygen in the boil by first moving the wort into the boil by input from below. Seems Kunze is pretty clear about oxidation, its effects on flavor stability and how to avoid it on the hot side.
But yea you are right, darn it, there is no mention of the word ‘underletting’.
Going back to the above list in section 4.6.4.2, one of the items says, “Keep oxygen away while mashing, if necessary pump in nitrogen” I don’t know about you, but that sounds like he is describing exactly what some of us low oxygen guys are already doing to solve this problem, purging our sealed systems with nitrogen. This is the next evolution and in my opinion brings us really very close to duplicating, on our scale, what the German macros do.
This is simply your opinion based on your own experience but isn’t supported by any of the science of brewing (with the obvious exception of Brulosophy) or the texts we just reviewed. By your own admission you haven’t tried the low oxygen methods and therefore are not in a position to give any evidence from direct observation of same. If you care to look at some of these papers you would find a lot of contradictory evidence against your bold assertions about HSA and the low oxygen methods.
M. Ditrych, W. Filipowska, G. De Rouck, B. Jaskula-Goiris, G. Aerts, M. L. Andersen and L. De Cooman – Investigating the evolution of free staling aldehydes throughout the wort production process
M. Kanauchi and C.W. Bamforth – A Challenge in the Study of Flavour Instability
Vanderhaegen, Neven, Verachtert and Derdelinckx – The Chemistry of Beer Aging: A Critical Review
Bamforth and Parsons – New Procedures to Improve the Flavor Stability of Beer
Jurkova, Horak, Haskova, Culik, Cejka and Kellner – Control of Antioxidant Beer Activity by the Mashing Process
Zufall and Tyrell – The Influence of Heavy Metal Ions on Beer Flavor Stability
Narziss – Technological Factors of Flavor Stability
Stephenson, Biawa, Miracle and Bamforth – Laboratory-Scale Studies of the Impact of Oxygen on Mashing
O’Rourke – The Role of Oxygen in Brewing
Journal of Agricultural and Food Chemistry – Oxidative degradation of lipids during mashing
Norja Lasko – Lipolytic and Oxidative Changes of Barley lipids During Malting and Mashing
B. Jaskula-Goiris, B. De Causmaecker, G. De Rouck, L. De Cooman and G. Aerts – Detailed Multivariate Modeling of Beer Staling in Commercial Pale Lagers
L. De Cooman and G. Aerts – The impact of wort production on the flavor quality and stability of pale lager beer
J. Savel – Negative role of oxidized polyphenols and reductones in beer
Again the preponderance of evidence as against your position on this and we went all through this in the thread about CO2. Your statement about the cost of high purity CO2 isn’t accurate either. I just purchased 50lbs of carbon dioxide for $110 and you can see for yourself the purity in the COA I have attached below.
There.. I hope that I have made my position clear and backed it with good evidence and maybe we can get past this issue that seems so stuck in your craw.
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