Potassium Metabisulfite Question

[RPh_Guy]

Maybe this will help...
https://www.researchgate.net/profil..._using_SPE/links/00b49515427f3a603f000000.pdf

 

[VikeMan]

Chemistry

Oh. Alright then.

 

[Yooper]

If they're doing it right they're also mixing it with an acid such as citric to lower PH below 3.0 in order to release SO2 which is indeed a sanitizer. Just filling your fermenter with a metabisulphite solution will not achieve anything and is only a waste of time and material.

No, we're not. Using k-meta at 40 grams per gallon of water. I just gave a talk on HomebrewCon on winemaking and covered sulfite quite a bit. That ratio makes a very high concentration of SO2 (which can really make you cough!). You can mix it with citric acid, but you don't have to for sanitizing surfaces.

Brewer's use it to remove chlorine/chloramine in a tiny dose, though.

 

[barada83]

Apologies to Vikeman- my response of Chemistry was only to the second part of the reply. The first part is buried in the quote where I went into much more detail. I imagine that seems a bit harsh

Challenging some dogmas here. Here are some articles that aren’t crazy deep into the organic chemistry
https://www.lenntech.com/processes/disinfection/chemical/disinfectants-chloramines.htm
https://pubchem.ncbi.nlm.nih.gov/compound/chloramine#section=3D-Conformer
Chlorine gas rapidly comes out of water. Ammonia is added to stabilize the chlorine and creates a soluble, less reactive chemically, and more long lasting disinfectant. It is almost impossible for a home brewer to filter out. It decomposes to ammonium nitrate. That’s not a very reactive chemical to phenolic compounds in general. It’s used to donate hydrogen to quench a Grignard reaction. Not much more that I have found besides that.
The biggest culprit of homebrewing off flavors is going to be through phenol production itself instead of chlorophenols. Polyphenols are present as lignin in the malt husk, and those can be extracted during the sparge with too high of temp or wrong ph usually. Also other aromatic phenolic compounds in hops. (VOL. 116, NO. 4, 2010 369A Discussion of Polyphenols in Beer Physical and Flavour Stability)
During the fermentation, yeast produce phenols. Some is through metabolism and can be increased through increased ferrulic acid that can be optimized through specific mash conditions when phenols are created on purpose like for a good German style Hefeweizen https://www.brewingscience.com/wp-content/uploads/2019/06/Wheat_Beer_Yeast__Fermentation.pdf .

I will summarize. Chlorine gas is pretty reactive but rapidly comes out of the water when sitting and especially boiling. You can easily filter it out as well. There are not very many phenols to react with that would make it into the fermentation unless your process is off. Chloroamine is probably not something to worry about and not much you can do about it anyway besides adding more chemicals into the system. One of those is sulfur in sodium metabisulfite. Other phenolic compounds and their production by yeast during fermentation is going to likely be your issue if you are detecting phenolic defects. Not your chlorine or chloroamines.
If there are any scientific papers on the topic of ammonia chloride or chloroamine reactivity to phenolic compounds I’d be happy to see those. Not just the same oft repeated but popular resources that do little more than say it happens when the two come together in a solution. Chemistry is a bit more complicated than having the right components in the same space. It requires conditions to be right. Wood doesn’t just spontaneously combust when oxygen is present but the chemical equation might give the appearance otherwise.

 

[VikeMan]

I will summarize.

If I understand your argument, it can be summed up as something like... mash conditions are not very good for production of chlorophenols. Therefore any chlorophenols produced in the mash can't affect the flavor of the beer. Is that a fair summary?

 

[RPh_Guy]

That’s not a very reactive chemical to phenolic compounds in general.

Did you have a look at the article I linked?

 

[VikeMan]

@dmtaylor, you're a Chem-E if I recall correctly. What do you make of this (the chlorophenol part of the discussion)?

 

[dmtaylor]

Does boiling remove chloramine?

Edit: I see that it does.

Not very well, takes friggin forever and a day.

 

[dmtaylor]

@dmtaylor, you're a Chem-E if I recall correctly. What do you make of this (the chlorophenol part of the discussion)?

Yes I am... by degree but maybe not in practice. My own 2 cents:

A lot of what @barada83 says seems to make sense, he/she seems to know some stuff... but I still have points and questions which we can continue to discuss openly among all of us:

One thing I know for sure: Chlorine (Cl2 gas) is extremely reactive. I cannot see how the presence of any hypochlorite, a.k.a. "bleach", a.k.a. "chlorine" prior to mashing and boiling could NOT cause chlorophenols in the finished beer. This is to say I'm sure any standard chlorinated tap water (maybe not chloramine?) will definitely be a problem. If your water smells or tastes like a swimming pool prior to brewing with it, you're certain to have problems.

But what about chloramine? That is what I don't know so much about personally. @barada83 seems to be making an argument that chloramine is so stable that it's really not causing a problem. Is it? I'll confess I don't really know off-hand, and that I'm too lazy to look it up, but he/she may be onto something, maybe. Worth some deeper review as we find the time.

Also there is the argument that more phenol comes from the yeast itself moreso than the mash. This I believe is likely. All yeasts produce phenolic compounds, and in my own experience I know more of my witbiers and hefeweizens have had little hints of chlorophenols in my finished beers than other styles have. If I were smart, I'd start using distilled water for these styles especially, and/or maybe quit the tap water + Campden treatment for all styles at some point. I like using tap water, it's cheap and convenient, but even the usual Campden doesn't always seem to get all of it out, or at least it seems this way to me, as I'm very sensitive to chlorophenol and it drives me up the wall.

Now... Could my "chlorophenol" be some other kind of phenolic compound, not really chlorophenol? On this I have my doubts. I think we know the smell and taste of Band-Aids or Chloroseptic when we sense it. It is what it is. Get that damned hypochlorite out of your brew, via Campden or boiling or both, or better yet, use RO or distilled. It's an annoying distraction and painful to dump a batch where you find a little too much chlorophenol in the finished product, what a waste. It ain't worth the risk. I feel myself talking myself out of using tap water (my municipality uses hypochlorite) anymore. But gosh... it's just that much cheaper!

But chloramine...... is it safe to brew with? Um, I really don't know. And I don't know anyplace around here in 'Sconsin that uses it, so I have no personal experience with brews made with it.

So there's my initial thoughts. Thanks for the shout VikeMan. Cheers all.

 

[mabrungard]

This is hilarious! Why would you take advice from a source that just joined the forum, spouts information that flies in the face of dozens of textbooks and probably your own experience, and hasn't identified who they are? Does the word 'trolling' come to mind?

Chlorine compounds are very reactive and they readily react with organic compounds to form other compounds. The reaction of hypochlorite or chloramines with organic-rich wort is of great interest to brewers and they KNOW that it readily forms chlorophenols in wort and beer.

I see that Sulfite somehow popped up in this metabisulfite thread. Please be aware that while both of those molecules have sulfur and oxygen and they share the term 'sulfite', they are quite different and you can't infer the behavior of one from the other. When you add sodium or potassium METABISULFITE (S2O5) to an aqueous solution, it dissociates to bisulfite ions (HSO3). Bisulfite is thermally-unstable ion and it will decompose into sulfur dioxide (SO2) gas which leaves the boiling wort or water.

SULFITE (SO3) is a different molecule and it is much more stable and it does not readily leave an aqueous solution. The likelihood that you produce sulfite in your wort from a metabisulfite addition is low, since wort is typically acidic and that reduces the formation of sulfite and encourages bisulfite formation.

 

[RPh_Guy]

Bisulfite is thermally-unstable ion and it will decompose into sulfur dioxide (SO2) gas which leaves the boiling wort or water.

Do you have a source for this?

Lots of empirical evidence by low oxygen brewers has shown that bisulfite ion does NOT decompose during the boil.

I see that Sulfite somehow popped up in this metabisulfite thread.

The use of the word "sulfites" by wine makers refers to all three species in equilibrium that form when metabisulfite ion decomposes in aqueous solution, even though the SO3 is the only one actually called sulfite by a chemistry definition. Good luck getting anyone to use the correct chemistry nomenclature.

SO2•H2O	↔	H+ + [HSO3]-	↔	2 H+ + [SO3]2-

...
+1 on the trolling.

 

[VikingBrewer]

Wow this thread has definitely grown from the OP, into way more info than I expected! I’ll have to try and wrap my head around some of these terms everyone are discussing.

 

[dmtaylor]

Do you have a source for this?

Chemistry!

 

[Die_Beerery]

Lots of empirical evidence by low oxygen brewers has shown that bisulfite ion does NOT decompose during the boil.

Only literal thousand(s) of batches using sulfites, verified with sulfite testing strips and DO meters.

 

[barada83]

ok- I get it. I just joined the forum. A lot of idiots out there who do the same and know very little. Maybe I’m one of those. Or maybe I have literally years of training on the subject and many others in brewing, biology, microbiology, general, organic, and analytical chemistry with actual degrees in these. How are you really to know? I do have all of those things. Let me introduce my experience- double major in biology and chemistry and a full medical degree with years of work at prestigious research universities in medical biological research and also worked in organic and analytical chemistry labs at the USDA.

Not only that, I’ve done everything I could to substantiate and support my assertions from way more valid sources than I have ever seen anyone do.

Personal attacks do nothing positive and labeling them as a troll does noting. Stick to the evidence and maybe learn something. Please, prove me wrong on what I have stated and maybe we can be friends and figure out something. Guess I’m too used to scientist discussions where the collegiality level is way higher.
RPh guy- I read the article you posted. It was a paper on methods on how to determine in a lab the presence of chlorophenols. It didn’t do any work to determine origin.

It looks like the sulfate discussion needs more evidence as well. I see no reason for HSO3 to decompose to gaseous SO2 through an acidic boil.

 

[Yooper]

It looks like the sulfate discussion needs more evidence as well. I see no reason for HSO3 to decompose to gaseous SO2 through an acidic boil.

Sulfite.
When I talk about 'sulfites' in winemaking, I'm referring to S02.

 

[barada83]

Sodium metabisulfite is basically a sulfide SO2and a sulfite SO3
Not after you are doing a chlorine quenching process. It forms hydrochloric acid and sulfates.
https://dnr.wi.gov/regulations/opcert/documents/WWSGDisinfectionADV.pdfLet me add though that the SO2 component is not real world. When disassociated in water it reacts like 2 sulfites. Check out reactivity section here:
https://en.m.wikipedia.org/wiki/Sodium_metabisulfiteGoing the other way to get to SO2 takes a lot of energy or biochemical processes.
https://link.springer.com/chapter/10.1007/978-1-4757-9438-0_2

 

[Yooper]

Sodium metabisulfite is basically a sulfide SO2and a sulfite SO3
Not after you are doing a chlorine quenching process. It forms hydrochloric acid and sulfates.
https://dnr.wi.gov/regulations/opcert/documents/WWSGDisinfectionADV.pdf

Yes, I know. sorry I wasn't clear. The original question as about adding k-meta or Na-meta, and asking if it was boiling off. We got a bit sidetracked, and I wanted to be clear to the original questioner that we WERE talking about metabisulfite. That's all I was saying, and I apologize that it wasn't explained well.

The science is great, and we need to show it but I didn't want to look like we went off the rails.

WAY too many people who are new to brewing science mix up potassium metabisulfite and calcium sulfate (gypsum) when we say "sulfite" or "sulfate" and they are difference substances for different purposes. Many people new to winemaking, for example, will start a query with "my girlfriend has a sulfate problem- should I add it to my wine?" so I always want to be clear which substance we are talking about at the beginning.

Anyway, please carry on!

 

[barada83]

Sulfate or sulfites don’t boil off. If you insist on treating the chloroamines, which I doubt the need to do so because they are nonreactive anyway (unless in sufficient quantity to smell them, then I would trade off that for the added sulfates), please check out the link from Wisconsin dnr for water treatment for amount to add calculations. You’ll need to know how much is present though. Chlorine itself it much easier to remove either through activated carbon filtering or just letting it sit. That seems very practical to me as a basic protection with little more required than some forethought, ie fill up your HLT the night prior and let sit.

Sulfites tend to work more on bacteria in the presence of oxygen. It forms hydrogen peroxide and selectively kills microorganisms without peroxidase activity.
So that’s why it’s so important in winemaking. Take out the bacteria that spoil batches without hurting yeast too much.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC168295/
I personally don’t like the idea of adding sulfates/sulfites to beer. The boil takes care of the microbes before fermentation and the chlorine can be treated in other ways without the addition of sulphur, something usually not pleasant to smell, taste, and it can cause negative reactions (medical) to some individuals.

 

[nine9bullets]

So I am new to this discussion and recently used some campden tablets to treat water before brew day at a ratio of 1 tablet per gallon after mistakenly reading the directions. It stated “Use as needed,1 tablet per gallon produces 30ppm of free SO2”. I didn’t realize until I listened to the Brülosophy podcast on this topic today and about how little it takes to treat for packaging. The beer is currently fermenting now and smells fine. What can I expect with this beer? Is that much SO2 a significant issue or is it even safe to drink? Im really bummed about it but mistakes happen.

 

[RPh_Guy]

So I am new to this discussion and recently used some campden tablets to treat water before brew day at a ratio of 1 tablet per gallon after mistakenly reading the directions. It stated “Use as needed,1 tablet per gallon produces 30ppm of free SO2”. I didn’t realize until I listened to the Brülosophy podcast on this topic today and about how little it takes to treat for packaging. The beer is currently fermenting now and smells fine. What can I expect with this beer? Is that much SO2 a significant issue or is it even safe to drink? Im really bummed about it but mistakes happen.

It likely all oxidized during the brewing process and aeration, into sulfate. Sulfate is perfectly harmless. In beer sulfate tends to increase the perception of bitterness.

 

[Yooper]

Sulfate or sulfites don’t boil off. If you insist on treating the chloroamines, which I doubt the need to do so because they are nonreactive anyway (unless in sufficient quantity to smell them, then I would trade off that for the added sulfates), please check out the link from Wisconsin dnr for water treatment for amount to add calculations. You’ll need to know how much is present though. Chlorine itself it much easier to remove either through activated carbon filtering or just letting it sit. That seems very practical to me as a basic protection with little more required than some forethought, ie fill up your HLT the night prior and let sit.

Sulfites tend to work more on bacteria in the presence of oxygen. It forms hydrogen peroxide and selectively kills microorganisms without peroxidase activity.
So that’s why it’s so important in winemaking. Take out the bacteria that spoil batches without hurting yeast too much.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC168295/
I personally don’t like the idea of adding sulfates/sulfites to beer. The boil takes care of the microbes before fermentation and the chlorine can be treated in other ways without the addition of sulphur, something usually not pleasant to smell, taste, and it can cause negative reactions (medical) to some individuals.

Brewers add sulfites (in the form of potassium metabisulfite usually) to the brewing water to react with chlorine/chloramines to remove that from the water.
Chlorine compounds interact with malt (and later, with yeast) to form chlorophenols. You absolutely should NEVER brew with chlorinated water for those reasons.
Chlorine will off-gas, but chloramines do not. They need to be removed, as they also don't boil off in any sort of reasonable time.

 

[barada83]

Chlorine gas (Cl2) reacts with Oxygen to form hypochlorous acid which then reacts with a ton of stuff. (Hypochlorous acid - Wikipedia)
That’s how everything gets destroyed. This reacts with amines NH2, to form a vastly less potent reactor but one that still has antimicrobial action without as many side effects and longer effect. Chlorine and hypochlorous acid move into and out of solution based upon pressure and agitation. It’s very unstable. As such, simple sitting overnight or boiling for a short amount of time will eliminate most of the dissolved chlorine and the hypochlorous acid as the equation pushes from hypochlorous acid to gaseous chlorine and out of the solution.
Of course, sulfites can remove activated hypochlorous acid by forming hydrochloric acid and sulfate. This works on hypochlorous acid as well as chloroamines. But the chloroamines are not phenol reactive to an appreciable extent. Nor do they do much of anything to my knowledge except aminate. (So the idea that chloroamines are an easy and direct way to form chlorophenols is pretty difficult case to make as far as I can tell, although I’m still trying to learn as well but all evidence is to the contrary. Chlorine aka chloride is bound in an ionic chemical composition in the chloroamines, similar to table salt which is sodium and chlorine, Na + and Cl- .
I know plenty of pro brewers that do nothing more than fill their HLT the night before brewing to off gas chlorine with no deleterious effects.

 

[VikeMan]

But the chloroamines are not phenol reactive to an appreciable extent.

Where is the evidence for this? I didn't see it in any of the links provided.

 

[barada83]

http://inchem.org/documents/ehc/ehc/ehc216.htm
Section 2.1 states it directly.

 

[VikeMan]

http://inchem.org/documents/ehc/ehc/ehc216.htm
Section 2.1 states it directly.

I assume you mean this...
"Chloramine presents the significant advantage of virtually eliminating the formation of chlorination by-products and, unlike chlorine, does not react with phenols to create taste- and odour-causing compounds."

Yet, there is no data given as evidence, or any supporting citation . I'd put it's reliability on a par with all the textbooks @mabrungard mentions. Or actually, less, because the textbooks are brewing specific. I could easily read the above statement, in the context of a treatise on public water treatment methods, to mean that the reaction isn't significant in drinking water, i.e. where phenols are fairly low. But even if it means exactly what it says, it's still unsupported in that document.

 

[barada83]

I'd put it's reliability on a par with all the textbooks @mabrungard mentions. Or actually, less, because the textbooks are brewing specific.

I’m really not following you on this. Not sure how science is more correct in brewing textbooks than in technical science documents prepared for water management and industry professionals, chemistry textbook and articles. Phenols don’t preferentially react only to brewing.
So I’ve shown evidence, now show yours. I’ve done my research. I’ve earned my science degrees. Please show me an article that analyzes the production of chlorophenols from chloramines brewing or otherwise. Then make sure they show suitable reaction conditions with the correct precursors and environment. I’ve searched hundreds of articles and found no support and presented a chemistry explanation. If I’m wrong you should be able to respond in kind, with evidence and explanation.

 

[VikeMan]

I’m really not following you on this. Not sure how science is more correct in brewing textbooks than in technical science documents prepared for water management and industry professionals, chemistry textbook and articles. Phenols don’t preferentially react only to brewing.

That's not what I said. I said drinking water may have lower levels of phenols than a mash, and that the quoted sentence may have been in the context of low phenol level drinking water.

If I’m wrong you should be able to respond in kind, with evidence and explanation.

I didn't say you were wrong. I said you haven't proved your assertion.

There is a huge acceptance in the professional and homebrew communities of the assertion that chloramines form chlorophenols in the mash, and a huge amount of anecdotal evidence of people experiencing it. And it's in the textbooks. You, with your dissenting opinion, are the one with a duty to prove otherwise. You haven't.

So I’ve shown evidence, now show yours. I’ve done my research. I’ve earned my science degrees.

Your degrees don't count as evidence.

 

[RPh_Guy]

Some other things to keep in mind:

1. Very few municipalities even use chloramine; the vast majority use chlorine.
2. The amount of sulfite needed to remove both chlorine and chloramine is very small and the reaction products and negligible. So even if the sulfite is useless in the case if chloramine, it's still not hurting anything.
3. Beer is a very complex medium that has a lot of enzymes that allow the transformation of otherwise unreactive substances.

 

[barada83]

What textbooks are you referring to specifically? It should be very easy for you to confirm your assertions with actual evidence.
Acceptance or practice does not mean correct or good science. Homebrewers do a lot of strange things that don’t really do anything and are based on false understanding and assumptions.