The Low O2 guys (I believe) have taken the approach to reduce/eliminate dissolved O2 in the mash thru use of sulfur based compounds, mash caps, etc.
Instead of focusing on reducing/elimination of O2, (which is kinda hard to do since it surrounds us), I think time is better spent focusing on the reaction.
Metal chelators like Brewtan B are fine but it's better to reduce them by using RO and changing your system to all stainless.
Essentially eliminating O2 in the mash actually isn't difficult. De-aerating the mash water, using an active scavenger like metabisulfite and mashcaps are quite effective as witnessed by in process DO meters that myself and a lot of other low oxygen guys have installed in our systems. I will see 0.00ppm O2 in the strike water at the underlet with a slight rise to 0.06ppm from oxygen dissolved into the grain itself but the meta will usually bring that right back to 0.00ppm within minutes and this will hold right the way through the mash and into the boil.
Low oxygen on the hot side is just one of those things that seems impossible until you do it and learn the tricks.
I have all stainless and start with distilled water in my mash process. ...but I don’t believe the material used to construct the system or lack of minerals in the brewing liquor addresses the oxidation reaction happening in the mash. IOW, the reaction still happens even in a stainless mash tun.
The change in temperature affects the amount of gas that a liquid can hold (i.e., the solubility of a gas in a liquid). Solubility decreases as temperature increases.
As I understand it, asuming normal atmospheric pressure and composition, water at 0˚C can hold a maximum of ~15ppm DO, while water at 50˚C can only hold ~5ppm. Once the water reaches 100˚C, solubility is zero.
Therefore, if you've brought water even close to a boil, you've removed virtually all the DO. I heat my brewing liquor to ~165*F (73*C) and mash at ~152*F (66*C) so I am mashing in at, and maintaining < 5 ppm DO. (I don’t measure DO.)
I am looking into approaching the reaction problem from a different angle. I am looking into targeting the reaction by binding the elements that cause it vs addressing the O2 — which at 5 ppm is not bad given Joe’s response (below).
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