It’s my understanding that only the sulfite form (SO3) has any ‘real’ antioxidant capability (and is a powerful one at that), but it exists in such low amounts at wine ph that it’s not esp useful (i.e. it’s a significant factor above pH of ~5). Bisulfite otoh (HSO3) isn’t an antioxidant, but it binds acetaldehyde produced and prevents further problems. Picking nits perhaps, but sometimes they need picking .
Yes, but the bisulfite is more likely to be used up…then the reverse will occur and molecular SO2 will drop as it equalizes.
I agree that it doesn’t tell the consumer anything about exactly how much SO2 is in the wine, that’s what I meant by '‘Minimum effective SO2’ is a marketing angle… It’s a way of saying ‘SO2 is necessary and effective and we use just enough.’ I thought that was clear.
The problem with SO2, in my opinion, is that
it’s necessary, in most cases, in the production of consistently good wine, but
the consumer knows nothing about it, except that wine sometimes gives them headaches and that chemicals are bad and evil.
I teach wine defect classes for consumers sometimes in SF, and the main reason I do it is to talk about SO2 and screw caps.
Why do wineries use that phrase on the label? I think they use it because they want people to know that SO2 is necessary, and that they don’t use more of it than they have to. It’s not specifically informative, obviously, but it’s not stupid, either.
Is there anyone other than Ridge who uses that terminology? Seems like a fine thing to say anywhere other than the ingredients listing which is where they use it along with other loaded terms like “hand harvested sustainably grown grapes”. Though I think every winemaker, but the no So2 naturalists, would say the same. How about keeping the marketing words to the marking paragraph on back labels and ingredients to the ingredient listing.
I would not mind total So2 on labels as it gives you a good idea of how heavy the regime of a given winery is. I don’t add any until malo is finished in barrel. I have definitely seen some pretty heavy use in some cellars approaching the legal limit.
Im not as big of a fan of what Bonny soon does by listing free along with total as free with decrease over time so its really a number at bottling not at consumption.
I let my FSO2 fall to 13-17 before adding SO2. I bring it to about 35-38 when I do. I essentially stole this method from some Right Bank producers who have been doing this more and more lately. SO2 adds were the big debate topic when I was there a few years ago.
Given pHs for my wines are 3.7+, I am not even sure I am making a difference. But I do it anyway and so does almost everyone else I know.
I try to keep TSO2 below 100 and find the fewer additions I do, the lower it seems to be. Adding a little SO2 at each topping seems to lead to higher TS02 levels for me. I have no idea if others find this true or not.
One winemaker I know brings his pH down to 3.1 to 3.2 on his reds with very large acid additions during fermentation, regardless of alcohol level, which usually exceed 15%. Thus, the SO2 additions are more effective. Then he uses Calcium Carbonate in bench trials with samples at 3.1, 3.2, 3.3… up to 4.0. The one he likes best becomes the target a couple weeks before bottling and he adjusts it all to bring it to bring the wine to his desired pH for mouthfeel. It seems to work to control VA, but I also find that his mouthfeels become too linear with such massive intervention, so I have never mimicked that method. I just can’t imagine (or maybe I just don’t want to) that such radical multiple-additions is the way to fix this issue without side effects.
That chart is a little confusing. The Y-axis is not molecular SO2, but the “required” amount of free SO2 required as a function of pH. What it really means is that as pH drops, there is more molecular SO2 (by virtue of forcing the equilibrium toward H2SO3, which is then in equilibrium with SO2), so you need less total SO2 addition. At least that’s my interpretation.
The white wine curve is for 0.8mg/l molecular SO2 (the amount of free SO2 at a pH to get 0.8 molecular). The red wine curve is for 0.5mg/l molecular SO2. This works because, as you point out, molecular and free stay in equilibrium for a given pH.
Yup, Joe. I saw it on a Donkey&Goat label…which is what got me to thinking on the subject.
And I’ve seen it on some WebSites in reference to a specific wine.
Tom
Yeah, I’ve seen it elsewhere too. I think a big question is: effective in what way? Some producers who say this (like Ridge) seem to mean effectively antimicrobial, which would relate to the numbers being discussed (based on pH). I’ve seen at least one “natural” wine with that statement or one just like it, and they were definitely not using enough for that purpose (typical faulty, biology experiment tasting wine). Maybe they meant effective as an antioxidant, which I think would be any measurable amount of free SO2, but only for some period of time.
Thanks for the info I have been a little out of the loop with the 15 month old.
Wow thats a lot of work to keep VA low. If I was going to do that much to a wine I would strongly consider to just de-VA the wine prior to bottling with RO and be done with it.
Alan, that’s how I think of it as well. In layman’s terms, the lower the pH, the more effective the SO2 addition will be at protecting the wine, so less of it is needed. Here’s a quick read for anyone interested in sulfite management: http://morewinemaking.com/public/pdf/so2.pdf
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