Author Topic: Sodium Sulfite vs Sodium Metabisulfite  (Read 1430 times)

MaltMaker

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Sodium Sulfite vs Sodium Metabisulfite
« on: April 17, 2017, 07:45:57 PM »
Would Sodium Sulfite (Na2SO3) be as effective at scavenging oxygen as Sodium Metabisulfite (Na2S2O5)?

In other words, would Sodium Sulfite bind more or less free O2 than the metabisulfite?

Not sure of the reaction with free O2 and the stoichiometry.  Anyone ever try this?

Reaction with free O2 results in sodium bisulfate?

2 Na2SO3 + O2 → 2 Na2SO4

Offline stpug

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Re: Sodium Sulfite vs Sodium Metabisulfite
« Reply #1 on: April 17, 2017, 08:33:01 PM »
I don't have any direct experience with sodium sulfite powder.  From the boiler-related source listed below, it appears that it would require ~33% more sodium sulfite than sodium metabisulfite to scavenge the same amount of oxygen.  How this factors into the flavor of the finished beer, or potential for sulfury results, I don't have any idea.  It's not quite as readily available as SMB is, but it does appear to be available.

Source: http://scrantonassociates.com/soc.pdf

Offline HoosierBrew

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Re: Sodium Sulfite vs Sodium Metabisulfite
« Reply #2 on: April 17, 2017, 09:33:35 PM »
it appears that it would require ~33% more sodium sulfite than sodium metabisulfite to scavenge the same amount of oxygen.


If that's the case, it sounds like a jump in Na content, too.
Jon H.

Offline stpug

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Re: Sodium Sulfite vs Sodium Metabisulfite
« Reply #3 on: April 17, 2017, 09:50:58 PM »
it appears that it would require ~33% more sodium sulfite than sodium metabisulfite to scavenge the same amount of oxygen.


If that's the case, it sounds like a jump in Na content, too.

I'd agree with you - good catch.  Same two atoms of sodium per molecule, so increasing the dosage by 33% for oxygen scavenging purposes would increase the sodium 33% as well.  However, I like that a possible alternative to SMB was brought up because it means we're starting to think more about the oxygen we let into our brew process on the homebrew level.

The idea of having utmost control over oxygen ingress into our brewing process is akin to starting with DI/RO water and controlling the mineral content we allow in.  It's another knob to turn that can help us dial in some details that were previously unattainable.  Maybe I desire some oxidized malt qualities in my barleywine, whereas I don't in my american light lagers - that kind of thing.

MaltMaker

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Re: Sodium Sulfite vs Sodium Metabisulfite
« Reply #4 on: April 18, 2017, 02:13:51 AM »
Agree with the sodium and the larger dose, just not sure what is actually produced during the reaction with free O2 and H2O?   If an abundance of SO2 is produced then this could be used with "more" Ascorbic Acid than usual but then you have more SO2...