"Minimum Effective SO2"???

[TomHill]

Some wineries that are using ingredient labeling will state “minimum effective SO2”. Some of them are in the
“natural” wine camp (Donkey&Goat), some are not (Ridge).
What kind of numbers (total SO2 at bottling) are we talking here:

1. White wines
2. Red wines
3. Wines w/ RS

Tom

[M_Officer]

Hi Tom,

Me thinks you’re stirring the pot again Tom as I’m sure you realize that this statement is more about marketing than anything else. One, obviously it is not defined and two, I’ve never known any winemaker who desires to use more than minimum effective SO2 in his or her wines. Also, it’s not really total SO2 that matters when it comes to effectiveness. It’s molecular. Generally, minimum effective SO2 for reds is 0.5 ppm molecular and for whites, it’s 0.8 ppm. Not sure about wines with rs but probably the same assuming filtration. But again, some winemakers may disagree with these levels and since the term “minimum effective SO2” is not defined, the statement lacks any real meaning.

[TomHill]

@M Officer

Hi Tom,

Me thinks you’re stirring the pot again Tom as I’m sure you realize that this statement is more about marketing than anything else. One, obviously it is not defined and two, I’ve never known any winemaker who desires to use more than minimum effective SO2 in his or her wines. Also, it’s not really total SO2 that matters when it comes to effectiveness. It’s molecular. Generally, minimum effective SO2 for reds is 0.5 ppm molecular and for whites, it’s 0.8 ppm. Not sure about wines with rs but probably the same assuming filtration. But again, some winemakers may disagree with these levels and since the term “minimum effective SO2” is not defined, the statement lacks any real meaning.

Awwwww, Mike…have I ever been known to ??

So the numbers I see are that wines w/ no added sulfites ar around 10-20 ppm. For BioDynamic/Demeter-certified, they have to be 100 ppm or less.
I’m just trying relate the “minimum effective SO2” to those numbers…which are, I believe, are the Total SO2 numbers and don’t really measure the effectiveness of the SO2.

And, of course, I understand that the term is used (by & large) for marketing purposes and to make my wine more “natural” than yours or FredFranzia’s.

Tom

[larry_schaffer]

The ‘effectiveness’ of SO2 is going to be be pH dependent as well. If you’ve got a lower pH wine, the level of free SO2 you’ll need to maintain to ‘ensure’ no oxidation will be much lower than if you have a wine with a higher pH . . .

[Bill_H_o_o_p_e_r]

This seems to be a big deal for some people and I find myself talking about it more than I personally think is necessary. I generally aim for 25-30mg/Liter free SO2 for dry or feinherb Riesling and a little more for sweet Riesling. I’m usually dealing with pH +/- 3.1, so less SO2/KMBS is needed to achieve this. My numbers would be low for some and too high for the SS crowd –though at almost every Biodynamic winery in Germany this would be right in the wheelhouse. My reasoning for using this amount is that I don’t like to drink oxidized wines (some people do) and it is important to me that Riesling in particular ages for a decade plus. On the other hand, too much will strip/conceal certain aromas and I think its up to the particular winemaker to decide where this line is for their wines.

In my opinion wines made without SO2 are like the grail in Indiana Jones and the Last Crusade: if you keep them at the winery in a cool cellar and don’t move them they’re probably ok. Once they pass the threshold of the winery door, all hell breaks loose. I think it’s completely ridiculous: I don’t use herbicides in the vineyard or (other) chemicals in the cellar but no one ever asks about that. This preoccupation with SO2 is front and center these days.

Cheers,
Bill

[Dan_R]

Here’s a chart that sort of brings together what Larry and Mike are saying. But even here, as Mike said, there’s no “minimum standard”. For instance, even when I was making 3.8+ pH Pinot Noir at Goldeneye, we were nowhere near what the chart would lead you to believe are the “minimum effective” free SO2 levels, and never had a problem.

[M_Officer]

And for the winemaker dealing with high pH fruit who refuses to add acid at crush, no way would I drink their wine if they said they used minimum effective SO2. It would probably burn my sinuses!

[Alan_Rath]

It seems to me that as long as there is some SO2 in solution, the concentration doesn’t matter that much (regardless of pH). Isn’t the required level more dependent on how good an average cork is, and how long the SO2 present (in either form, SO2 or HSO3) will last?

[Oliver_McCrum]

‘Minimum effective SO2’ is a marketing angle, as was pointed out above. It’s a way of saying ‘SO2 is necessary and effective and we use just enough.’

I think many consumers don’t understand why producers use SO2, this is not a bad idea to me.

[larry_schaffer]

@Alan Rath

It seems to me that as long as there is some SO2 in solution, the concentration doesn’t matter that much (regardless of pH). Isn’t the required level more dependent on how good an average cork is, and how long the SO2 present (in either form, SO2 or HSO3) will last?

Good points - and I have to believe that yes, these things come into play, as does the level of dissolved oxygen in the wine (the higher that level, the less effective SO2 will be in the long term). Many of these things, though, are pH dependent - in a lower pH situation, the same amount of Free SO2 will ‘last longer’ and therefore be ‘more effective’ in preventing oxidation than with a higher pH situation . . .

Cheers.

[larry_schaffer]

@M Officer

And for the winemaker dealing with high pH fruit who refuses to add acid at crush, no way would I drink their wine if they said they used minimum effective SO2. It would probably burn my sinuses!

Yep - and this seems to happen even with additions

Cheers!

[Jim_Anderson]

@Dan R

Here’s a chart that sort of brings together what Larry and Mike are saying. But even here, as Mike said, there’s no “minimum standard”. For instance, even when I was making 3.8+ pH Pinot Noir at Goldeneye, we were nowhere near what the chart would lead you to believe are the “minimum effective” free SO2 levels, and never had a problem.

Best and most concise answer.

Of course, we use SO2 homeopathically. But only at minimum effective levels.

[Alan_Rath]

@larry schaffer

Many of these things, though, are pH dependent - in a lower pH situation, the same amount of Free SO2 will ‘last longer’ and therefore be ‘more effective’ in preventing oxidation than with a higher pH situation

But even at higher pH, where the equilibrium is pushed toward SO3–, and lower concentration of SO2, as SO2 is used up there is still a sink of SO3 to continue supplying it. It’s not like it disappears. Having said that, I’m just a chemist, so I can comment on the simple stuff, but I have no idea what really goes on in wine

[Stewart_Johnson]

To muddle things further, you also need to ask what you’re being “effective” against. Mike spelled out the anti-microbial molecular SO2 standard. But if you’ve sterile filtered (or at very low pH, like Bill), you might be more concerned with effectiveness against oxidation/aldehydes and your main reference point would be free SO2. I usually don’t even measure my total SO2, since that’s not effective against much, other than maybe malo.
I screwed up an SO2 add, to the very high side, with my first vintage of viognier – didn’t bother to put on reading glasses to be able to see that someone had set the crappy little winery scale to ounces instead of grams. That vintage sailed through bottling without a moment of bottle shock (or bottle variation) and, I thought, carried the extra SO2 pretty well and might even have shown some extra minerally verve. I haven’t quite been ready to commit to SO2 overdoses in subsequent vintages, but I have been alert to correlations between perceptible SO2 and minerality in whites. Just a hypothesis at this point, but I’m definitely not in the “SO2 is a necessary evil” camp.

[M_Officer]

@Alan Rath

It seems to me that as long as there is some SO2 in solution, the concentration doesn’t matter that much (regardless of pH). Isn’t the required level more dependent on how good an average cork is, and how long the SO2 present (in either form, SO2 or HSO3) will last?

Not exactly Alan. SO2 has four beneficial properties for wine. It serves as an antiseptic, antioxidant, antioxydase, and flavor preserver. Much of the SO2 in wine is in a bound form with acetaldehyde. This is irreversible. Some SO2 is bound but to other things like sugars, phenols, and acids. These compounds usually have a high constant of dissociation and act as a reserve for free SO2 as free gets used up in combining with oxygen (forming sulfuric acid), i.e., this is SO2 playing the role of a antioxidant. But only the molecular portion of SO2 can play the antiseptic role and that is pH dependent as Dan’s chart shows.

@Oliver McCrum

I think many consumers don’t understand why producers use SO2, this is not a bad idea to me.

Are you saying “minimum effective SO2” on the label is not a bad idea? To me it doesn’t tell the consumer anything. One, it’s not defined. Two, you could have a red wine of pH 3.8 that says on the label it used minimum effective SO2. That could translate to a total SO2 of 320 ppm and a free of 50 ppm. On the other hand, you could have a red wine at pH 3.4 and not labeled as having used minimum effective SO2. It could have a total SO2 of 160 ppm and 20 ppm free. For the consumer looking to minimize sulfite ingestion, they would probably gravitate to the first wine even though it has double the SO2 in it.

[Chris_Seiber]

@Jim Anderson

Of course, we use SO2 homeopathically. But only at minimum effective levels.

Personally, I just want to make sure my wine is free of PABA. I’ve got a problem with PABA.

[Drew_Goin]

It’s probably like the case of wineries posting approximate alcohol levels for easier/cheaper labelling.

Also, if Winery X puts the SO2 levels for the vintage 2013 on a label, customers might be disconcerted when the levels are different on the following vintage’s label.

Just my uneducated opinion…

[Alan_Rath]

@M Officer

But only the molecular portion of SO2 can play the antiseptic role and that is pH dependent as Dan’s chart shows.

Thanks for expanding and clarifying. But what I’m saying is that as “molecular” SO2 is used up, even at fairly high pH (where the ratio of molecular SO2 to HSO3- is on the order of 1:100) there is a huge reservoir of bisulfite to replenish that loss. That ratio will just continue in equilibrium. The absolute concentration will drop, of course, but assuming there isn’t something eating the SO2 quickly shouldn’t it keep replenishing for quite a while?

[Chris_Seiber]

I remember a coworker talking about how wine gives her headaches, but when she traveled around France, the wine didn’t give her headaches because they don’t use sulfites there.

Which is wrong on pretty much every level, but I had the sense not to disagree with her there. It definitely is a widely misunderstood and overwrought issue.

It probably was true that she didn’t get headaches from the wine there, though I would guess the reason was that she was on vacation, probably less stressed, more relaxed, getting more sleep and rest, in a better mood, and so forth.

[R_Gilbane]

Non-homeopathic SO2 usage is a killer.