Perceived Flavor threshold: sodium metabisulfite (SMB) and potassium metabisulfite (Campden)

[Unicorn_Platypus]

Brulosophy recently conducted an interesting experiment in using SMB to reduce cold side oxidation in NEIPA:

http://brulosophy.com/2019/09/23/co...sulfite-smb-at-packaging-exbeeriment-results/

They used a dosing of .3g per 5 gallons which amounts to ~10ppm

There was a noticeable impact in the experiment of the dosed vs. non dosed batch. However, it didn't seem to be enough to rid the batch of undesirable oxidation completely.

This could be because the dose wan't high enough, or it was already too late to save the beer.

I'm interested in going with a higher dose. Was wondering if anyone knew the the perceived flavor threshold for SMB or Campden? And if there's a potential difference between using SMB vs. Campden.

If going with a higher dose doesn't impact flavor, I figure why not go higher.

I currently have relatively stable shelf life for my dry hopped beers with < 4oz of dry hop in the keg. However, I have had occasional oxidized batches when going higher. I'm careful to purge gets and do low O2 transfers with CO2. Looking to add additional cheap insurance to prevent oxidation, and this looks like it might be worth a shot.

I'm carbonating all my beers in the keg, so yeast viability for fermentation in the bottle isn't a concern.

 

[Vale71]

If going with a higher dose doesn't impact flavor, I figure why not go higher.

For one thing, because SMB is not good for your health. Sulfites are often the reason why some people can't drink wine without feeling sick and not just from the alcohol.

 

[Cavpilot2000]

For one thing, because SMB is not good for your health. Sulfites are often the reason why some people can't drink wine without feeling sick and not just from the alcohol.

True, but once it is exposed to oxygen, it is no longer sulfite.
That said, I'm not a big fan of dosing after fermentation.
We in the LOB/LODO community use it, but make sure all of the sulfite is expended at pitch time (by oxygenating while there is active yeast).
Also, sulfites occur naturally during fermentation as well.
And they are standard additions in cider, mead, and winemaking.


OP,
It is not so much a problem with flavor threshold, but you can/will get rotten egg farts if there are a decent amount of sulfites, even if you can't taste them.
You may taste or smell a hint of sulfur, but in some beers, like a German Pilsner, you are supposed to have a hint of sulfur.
When I started LODO, before I learned to expend all the sulfite through exposure to oxygen, I would get egg farts from drinking the beer, even though it tasted fine - that was from sulfites carrying over into the final product.

Also, your idea of "just add more" fails to take into account the time factor.
The sulfites will become expended over time as the beer is exposed to oxygen. At some point, you have "too much", later you will have "just enough", and eventually, you will have none left and your beer will oxidize like any beer not protected with sulfites.

Oxidation cannot be prevented, only delayed. So in the ExBeeriment, they ikely had just enough in the beginning, but over time, there was no longer enough to protect the beer because the sulfites get "used up" as they are exposed to oxygen.

 

[Vale71]

T
And they are standard additions in cider, mead, and winemaking.

Standard doesn't necessarily mean that it's healthy or desirable. The issue with using sulfites in beer is also that, unless you only brew 10% ABV beers, a standard serving of beer is quite larger than a standard serving of wine or any equivalent beverage. If you dose it like winemakers do you'll end up ingesting quite a lot and that will surely make you feel much worse than the alcohol alone would.
Of course with minimal dosage you won't have any ill effects as it will all be used up in a short time but then it won't be really effective against oxidation so why bother?

 

[RPh_Guy]

Sulfites are often the reason why some people can't drink wine without feeling sick and not just from the alcohol.

You have a scientific source for that? I think that's a myth, excluding asthmatics.

Still, I agree the minimum amount needed should be used, which in this case is none.

There are other ways to minimize oxygen.

Was wondering if anyone knew the the perceived flavor threshold for SMB or Campden?

There shouldn't be any taste from the sulfite, used at reasonable dosages, under 100ppm.

And if there's a potential difference between using SMB vs. Campden.

Sodium has a flavor impact whereas potassium does not.
By the way, not all Campden contains potassium. The tablets I have are sodium.

Cheers

 

[Vale71]

You have a scientific source for that? I think that's a myth, excluding asthmatics.

I did say some people, didn't I?
And even if I don't know for sure whether I'm one of them I still prefer not to drink stuff that might have some toxicity, however small. With the exception of ethyl alcohol of course...

 

[RPh_Guy]

You don't know if you have asthma?
Interesting.

 

[Unicorn_Platypus]

True, but once it is exposed to oxygen, it is no longer sulfite.
That said, I'm not a big fan of dosing after fermentation.
We in the LOB/LODO community use it, but make sure all of the sulfite is expended at pitch time (by oxygenating while there is active yeast).
Also, sulfites occur naturally during fermentation as well.
And they are standard additions in cider, mead, and winemaking.


OP,
It is not so much a problem with flavor threshold, but you can/will get rotten egg farts if there are a decent amount of sulfites, even if you can't taste them.
You may taste or smell a hint of sulfur, but in some beers, like a German Pilsner, you are supposed to have a hint of sulfur.
When I started LODO, before I learned to expend all the sulfite through exposure to oxygen, I would get egg farts from drinking the beer, even though it tasted fine - that was from sulfites carrying over into the final product.

Also, your idea of "just add more" fails to take into account the time factor.
The sulfites will become expended over time as the beer is exposed to oxygen. At some point, you have "too much", later you will have "just enough", and eventually, you will have none left and your beer will oxidize like any beer not protected with sulfites.

Oxidation cannot be prevented, only delayed. So in the ExBeeriment, they ikely had just enough in the beginning, but over time, there was no longer enough to protect the beer because the sulfites get "used up" as they are exposed to oxygen.

So you are saying when "too much" has been added there is a discernible negative impact in the flavor profile (until you reach "just enough")?

 

[Unicorn_Platypus]

Standard doesn't necessarily mean that it's healthy or desirable. The issue with using sulfites in beer is also that, unless you only brew 10% ABV beers, a standard serving of beer is quite larger than a standard serving of wine or any equivalent beverage. If you dose it like winemakers do you'll end up ingesting quite a lot and that will surely make you feel much worse than the alcohol alone would.
Of course with minimal dosage you won't have any ill effects as it will all be used up in a short time but then it won't be really effective against oxidation so why bother?

good point on the volume being ingested of beer vs. wine

 

[Cavpilot2000]

Standard doesn't necessarily mean that it's healthy or desirable. The issue with using sulfites in beer is also that, unless you only brew 10% ABV beers, a standard serving of beer is quite larger than a standard serving of wine or any equivalent beverage. If you dose it like winemakers do you'll end up ingesting quite a lot and that will surely make you feel much worse than the alcohol alone would.
Of course with minimal dosage you won't have any ill effects as it will all be used up in a short time but then it won't be really effective against oxidation so why bother?

A: aside from the small percentage of people who have negative reactions to sulfites, if there were a health problem with sulfites in alcohol (any more than the alcohol itself) we would likely know about it, since probably 99.999% of every bottle of wine made in the last 40-50 years has been dosed with sulfites post-fermentation (the only ones that aren't have that specifically stated on them, and that is a VERY small percentage, as it is a fairly recent thing practiced usually only by organic wineries).

B: Again, used properly in beer, there should not be sulfites, or they should be minimal when you drink it (as they convert to other compounds when exposed to oxygen, binding the oxygen molecules and preventing oxidation).

C: I am actually in agreement with you that it is a questionable practice with more potential downside than upside when added AFTER fermentation, unless aging for a long time. I only use them before fermentation, which done properly, leaves no sulfites in the beer other than what the yeast naturally produce (which usually gets converted also as part of the yeast's antioxidant properties).
I also won't use plastic-based clarifying agents (polyclar, etc), but that's a different matter altogether.

 

[Cavpilot2000]

So you are saying when "too much" has been added there is a discernible negative impact in the flavor profile (until you reach "just enough")?

Yes, with a caveat: some beers have a desirable sulfur element in the aroma (not so much the flavor), so it could be mistaken for yeast-derived desirable aromatics in such beers, so "negative" is a questionable term.
But I imagine when there truly is too much, then there is too much and you will notice it.

If you recall, in the experiment, he preferred the non-treated beer early on, suggesting there was a perceptible negative (style dependent) element, even though he never described it as sulfurous. That was probably when there was "too much".
Then he liked the treated beer better - once some of the sulfites had dissipated by binding with oxygen. That was "just right".
Again, it's a moving target with a window of optimal performance.

Like I said, I knew early on with my LODO beers that I had not gotten all the sulfites out, or had over-dosed it, when I would drink it and within a few hours has sulfury, malodorous flatulence. I would call that perceptible and negative, but not in the beer.

 

[RPh_Guy]

So you are saying when "too much" has been added there is a discernible negative impact in the flavor profile (until you reach "just enough")?

As I said, used in reasonable amounts there won't be any flavor from the sulfite.

 

[RPh_Guy]

Yes, with a caveat: some beers have a desirable sulfur element in the aroma (not so much the flavor), so it could be mistaken for yeast-derived desirable aromatics in such beers, so "negative" is a questionable term.

You're talking about yeast-derived compounds, hydrogen sulfide.
Added post-fermentation it's not an issue.

 

[Cavpilot2000]

You're talking about yeast-derived compounds, hydrogen sulfide.
Added post-fermentation it's not an issue.

Right, but they both can be perceived as a sulfur aroma, so my point is it's hard to tell which you are picking up.

 

[RPh_Guy]

Not in this case. You could easily detect sulfide before adding sulfite by smelling and tasting a sample of the beer.
Since no fermentation is occurring, there will be no sulfide produced by the yeast, so only the sufite could add sulfurous flavors.

I don't believe sulfite can directly cause any off-flavors in beer. Sulfite only produces off-aroma/flavor when the amount of molecular SO2 exceeds about 1.2ppm. It will never be that high at beer pH when used in reasonable amounts.
At pH 4, you'd need over 180ppm of free sulfite to approach the flavor threshold.

Sulfite pre-fermentation like in LODO may stress the yeast into producing sulfide. That's a very different usage, and not applicable to this situation.

 

[artichoke]

Adding a small amount of SMB (Sodium Metabisulphite) at packaging really does work very well to preserve freshness. Winemakers have been doing this for years, so why not leverage off of what they already know.

As for sulphur aromas and flavours coming through, they don't as long as you dose with small amounts. None of my beers I send into competition every have comments about sulphur being apparent, unless it's a german lager where I've used a sulphur producing yeast and it's to style. But that never happens as a result of the SMB additions.

Last point; although I am not a medical doctor, I'm fairly certain that the alcohol in beer will damage your health much more effectively than an almost negligible (10 - 20 ppm) amount of SMB added to the beer.

- Artichoke.

 

[Cavpilot2000]

Not in this case. You could easily detect sulfide before adding sulfite by smelling and tasting a sample of the beer.
Since no fermentation is occurring, there will be no sulfide produced by the yeast, so only the sufite could add sulfurous flavors.

I don't believe sulfite can directly cause any off-flavors in beer.

Argh - I know that - you're mis-reading my point.
I'm talking about finished beer, which is all we really care about anyway. If you detect sulfur (could be aromatic, which is at a much lower threshold than tasting for many people), you won't know if it is sulfide or sulfite.
Unless you're saying that sulfite has no aromatic/smell properties, to which I would respectfully, but vigorously, disagree.

And yes, sulfite will stress yeast and delay/slow fermentation, but if you're doing it, the yeast don't really spend any appreciable time in contact with sulfites. Generally only minutes. Like single digit minutes.

 

[RPh_Guy]

I'm talking about finished beer

Well, I'm talking about beer that finished fermenting, finished with hopping, and ready for packaging, when post-fermentation sulfite would be added.
Whether or not you agree that's "finished", I'm not sure, but you would be able to detect a sulfide aroma at that time even without carbonation.

Unless you're saying that sulfite has no aromatic properties, to which I would respectfully, but vigorously disagree.

This is in fact what I'm saying.
As you pointed out, "99.999% of every bottle of wine made in the last 40-50 years has been dosed with sulfites post-fermentation". You've had wines. They aren't sulfurous. Yet, they contain plenty of sulfite, enough to allow it to last for years of aging.
Winemakers aim for 0.6-0.8ppm molecular SO2 at the time of consumption.

I've used sulfite quite a bit (pre- and post-fermentation in wines and also in LODO beer) and I've learned all the science behind it. I'm sure the "sulfur" (hydrogen sulfide) you've detected was produced by yeast.

Try it yourself: take a small glass of RO water (NOT chlorinated). Dump in a bunch of sulfite, stir to dissolve, now smell. There's basically no aroma. The sulfite is in the bisulfite ion form, as it will be in beer.
Now add some acid. Smell again (actually, use your hand to waft the fumes toward you). It's a little noxious, but absolutely nothing like hydrogen sulfide. The acid (low pH) shifts the sulfite into the aromatic molecular SO2 form, which would not be present in beer when used in reasonable quantities.
(Congrats, you just made a very effective sanitizing solution.)

Note: The amounts used in this experiment are vastly greater than what's used in wine and beer.

Warning: SO2 fumes are indeed toxic, so avoid breathing it too much. And don't do this if you have asthma.

Cheers

 

[Robert65]

Kunze gives appropriate dosing at packaging as: Sodium and/or potassium metabisulfite up to 20g/hL in combination with ascorbic acid at 2-8mg/hL (so 0.2ppm metabisulfite and a mind bogglingly small amount of AA,) so as to release up to 10ppm molecular SO2. So it appears that a far more minuscule amount than discussed here is effective, and will be undetectable and harmless. Of course this is one of those things Kunze gives explicit directions for, touts its profound benefits, and then (with a wink and a nudge) admonishes we must never, ever actually do lest the Reinheitspolizei come for us in the night.

 

[RPh_Guy]

Worth mentioning:
Sulfite and ascorbic acid work synergistically.
BrewTan B can also be added for further benefit.

 

[ScrewyBrewer]

I once dosed a Pineapple Pale Ale with potassium sulfate and potassium metabisulfite, at a rate of 1.0 campden tablet and a 0.5 teaspoon of potassium sorbate per gallon. Fermented with White Labs WLP051 - California Ale V Yeast the sulphur smell was overwhelming four days in.

Fortunately the sulphur wasn’t noticeable after a week of cold crash and carbonation it tasted great.

 

[RPh_Guy]

metabisulfite up to 20g/hL in combination with ascorbic acid at 2-8mg/hL (so 0.2ppm metabisulfite and a mind bogglingly small amount of AA,) so as to release up to 10ppm molecular SO2.

Whoa, hang on.
20g/hL is 200ppm
And the AA is 0.02-0.08ppm

10ppm molecular SO2 is about 10 times more than you'd ever want. ... And even 200ppm of sulfite wouldn't release that much in beer anyway.

Sure you have those amounts right?

I once dosed a Pineapple Pale Ale with potassium sulfate and potassium metabisulfite, at a rate of 1.0 campden tablet and a 0.5 teaspoon of potassium sorbate per gallon. Fermented with White Labs WLP051 - California Ale V Yeast the sulphur smell was overwhelming four days in.

Why did you add sorbate?
There was fermentable sugar?
Did you rack and fully clarify (crystal clear, zero sediment) before adding the stabilizers?
Easy mistake to make. It's extremely likely the yeast produced sulfide while struggling to continue fermentation. That's why we don't try to stabilize beer.
Also, 67ppm of sulfite is a little excessive for what we're discussing.

 

[Robert65]

Whoa, hang on.
20g/hL is 200ppm
And the AA is 0.02-0.08ppm

Sure you have those amounts right?

Copied directly from the 2014 edition of Kunze, up to 20g/hL metabisulfite, which does look absurd now I look at it (I must have subconsciously made a conversion error resulting in a more reasonable sounding dose) and 2-8mg/hL AA (I'll buy that.) Could be a typo? Should probably read *20mg/hL*? Maybe somebody smarter than me can figure out what doses of metabisulfites and AA would release the stated 10ppm maximum of SO2, assuming that standard is stated correctly. I bet one little "m" was omitted by the composer and overlooked by proofreaders.

 

[RPh_Guy]

Copied directly from the 2014 edition of Kunze, up to 20g/hL metabisulfite, which does look absurd now I look at it (I must have subconsciously made a conversion error resulting in a more reasonable sounding dose) and 2-8mg/hL AA (I'll buy that.) Could be a typo? Should probably read *20mg/hL*? Maybe somebody smarter than me can figure out what doses of metabisulfites and AA would release the stated 10ppm maximum of SO2, assuming that standard is stated correctly. I bet one little "m" was omitted by the composer and overlooked by proofreaders.

Sorry, I ninja edited my above post while you were responding.

10ppm molecular SO2 is about 10 times more than you'd ever want. ... And even 200ppm of sulfite wouldn't release that much in beer anyway.

First, Kunze is referring to the weight of sodium metabisulfite whereas I am referring to SO2 when I say "sulfite". They're not equivalent.

200ppm sodium metabisulfite is a reasonable maximum.
Let's say average beer pH is 4.3.
200ppm of sodium metabisulfite would give 135ppm SO2 and about 0.4ppm molecular SO2 at that pH, which is still well under the flavor/aroma threshold.
In a 4.0 pH beer, it's around 0.9ppm molecular SO2. Still with plenty of margin.

 

[Robert65]

Well then that whole section of Kunze looks screwy. Luckily I'll never try to employ it, not because I have any regard for the Reinheitsgebot, which I find amusing at best, but because I see no need in my process.

 

[RPh_Guy]

Yeah the author is not infallible. I don't even have the book but I've also found mistakes in other excerpts quoted to me. (Not that I'm superior or anything like that.)

 

[Robert65]

Yeah the author is not infallible. I don't even have the book but I've also found mistakes in other excerpts quoted to me. (Not that I'm superior or anything like that.)

Yeah, there's the room for error in getting any work into print, with the added complication that composers and proofreaders may not be technically savvy enough to be able to catch such errors, and then double the opportunity for such mistakes in bringing to print an English translation... sometimes you have to make an educated guess at what was intended.

 

[RPh_Guy]

I didn't realize it was a translation. That explains the awkward wording. I should get a copy.

 

[Robert65]

I didn't realize it was a translation. That explains the awkward wording. I should get a copy.

I assume "English Edition" just means technical writers have translated the original German edition. BTW there's a brand new 2019 edition out. If you do get it, I'll be very interested in whether this information reads very differently!

 

[Unicorn_Platypus]

Just for a frame of reference...

what dosing of potassium metabisulfite would be needed in 5 gallons to achieve 100ppm?

 

[RPh_Guy]

To achieve 100ppm SO2 in 5 gal:
3.3g potassium metabisulfite
Or
2.8g sodium metabisulfite

It had slipped my mind but I believe that Kunze is going by the weight of sodium metabisulfite powder when he's talking about sulfite usage. (That's not what's done in the wine world.)
So based on his suggested use of sodium metabisulfite powder, the max "SO2" concentration he suggests is 135ppm, closer to what I originally suggested. This corresponds to a 0.86ppm molecular SO2 level, even in a 4.0 pH beer.

I know this is confusing.

 

[RPh_Guy]

Edited for clarification.

 

[Cavpilot2000]

Now add some acid.

You mean like a 4.4 pH ethanol solution?
And yes, I’ve made such a solution for adding to cider (using boiled distilled water) - it burns the crap out of your eyes and nose and will even eat through the lid of a mason jar over time.

Look, I’m not trying to be argumentative, but my experience indicates that if you have excessive sulfites in your beer (like you didn’t get rid of them after LODO brewing prior to pitching, or added too much post-fermentation), you could have a noticeable effect. For me it’s mostly in the form of sulfurous flatulence, which happens predictably with over-sulfited beer.
The experience is very different form normal yeast-derived sulfide, otherwise it would happen with virtually every lager beer consumed, which it doesn’t, only when I’ve had unspent or post-ferm sulfites.
Maybe it’s not from sulfite, maybe it’s from alien anal probes, or the magnetic poles of the earth being askew, but it is an observable, repeatable phenomenon (wait, that sounds like science...) that mysteriously coincides with unspent sulfites in my beers.
Personally I think there might be some validity to the alien anal probe theory...

 

[Cavpilot2000]

I’m not saying there isn’t merit to adding sulfites pre-packaging, but I am saying that a) you can overdo it, and b) you can’t prevent oxidation, only delay it, which doesn’t mean it isn’t a worthwhile pursuit - but there are many ways to get there.

This method works well for the “I haven’t done anything to protect my beer from oxygen so I’m looking for a band-aid at packaging” approach.

 

[Robert65]

This method works well for the “I haven’t done anything to protect my beer from oxygen so I’m looking for a band-aid at packaging” approach.

Or for the audience Kunze is specifically addressing, those who require protection against oxidative staling in packaged goods, subject to bottle cap ingress, hot storage conditions, and so on, over a 12 month guaranteed shelf life. And he is quite clear that it is only delaying oxidation, but that it has a remarkable effect to that end. In fact, it will do nothing for the "I haven't done anything" crowd. There is no way to reverse the inevitable, if not yet manifest, effects of exposure already allowed. The brewers seeking this insurance must have ensured rigorous oxygen exclusion upstream, right up to the point of packaging in an oxygen purged environment.

 

[RPh_Guy]

You mean like a 4.4 pH ethanol solution?

You can ask questions without being snarky.

The pH matters. Here's a visual:

A 4.4 pH solution produces a negligible amount of molecular SO2 when the level is sulfite is appropriate.
Winemakers adjust pH down to 3.8 if needed, so the sulfite will actually form the molecular SO2 needed to suppress microbes.

The SO2 aroma/sensation is extremely different than H2S aroma. There's absolutely no way to confuse them. Hydrogen sulfide has a very distinct and powerful rotten egg / rhino fart quality, while SO2 is more like a burning without any other particular quality.

but my experience indicates that if you have excessive sulfites in your beer (like you didn’t get rid of them after LODO brewing prior to pitching, or added too much post-fermentation), you could have a noticeable effect.

I agree this statement is true, but only for sulfite added prior to yeast fermentation, because the yeast are likely to produce hydrogen sulfide.

Your experience is only with pre-fermentation sulfite and that doesn't apply to post-fermentation sulfite.

For me it’s mostly in the form of sulfurous flatulence, which happens predictably with over-sulfited beer.

You're basing your entire opinion on your farts?

... Have you actually measured the sulfite level in these "over-sulfited" beers you're making? Or are you operating purely under the assumption that there are residual sulfites?

Does this also happen with other beverages that contain sulfites? E.g. wine?

Personally I think there might be some validity to the alien anal probe theory..

I'm going to assume you're intoxicated.
Otherwise I think this discussion is over.

P.S. Look at that brulosophy page. Several commenters have repeatedly used sulfite post-fermentation with success, even if bottle conditioning. Not to mention Kunze condones it. I'm not pulling this out of my rear.

 

[Unicorn_Platypus]

I produced some sulfurous flatulence tonight after eating mexican food

 

[Robert65]

I produced some sulfurous flatulence tonight after eating mexican food

Better check to be sure it wasn't alien probes.

 

[RPh_Guy]

I’ve made such a solution for adding to cider (using boiled distilled water) - it burns the crap out of your eyes and nose

In case anyone is wondering, you should gently dissolve sulfite in a bit of cool water immediately before adding it (to cider or beer or whatever).
You should generally not mix anything acidic into a highly concentrated sulfite solution, or store it for long periods.

 

[Vale71]

Copied directly from the 2014 edition of Kunze, up to 20g/hL metabisulfite, which does look absurd now I look at it (I must have subconsciously made a conversion error resulting in a more reasonable sounding dose) and 2-8mg/hL AA (I'll buy that.) Could be a typo? Should probably read *20mg/hL*? Maybe somebody smarter than me can figure out what doses of metabisulfites and AA would release the stated 10ppm maximum of SO2, assuming that standard is stated correctly. I bet one little "m" was omitted by the composer and overlooked by proofreaders.

Nope, 200 mg/l sounds about right and is regularly found f.e. in white wines. Like I said, since you cannot predict exactly how long the beer will be stored you'll need to add an amount tailored to the maximum expected shelf life, because if the SMB runs out before the beer is consumed oxidation will start happening, like the Brülosophy experiment quoted earlier (with minimal dosage) clearly showed.

BTW I've checked the German edition of Kunze and it says "up to 20 g/hl" so it appears nothing was lost or changed in translation.