Sulphur dioxide is a colourless gas with a strong and unpleasant smell. Although it is toxic, many processed foods, and wines in particular, contain sulphur dioxide as a preservative.
A small amount is used, yet some people are highly allergic to sulphur dioxide. The WHO (World health Organization) set .7 mg per kilogram of weight per day as safe. Hence, a 60 – 80 Kg. Weighing person can ingest 42 – 56 mg. per day.
Some wines contain 10 – 200 mg. per litre. According to US laws, the label must state that the wine contains sulphite (the generic term used for sulphur dioxide) but not quantity, simply because sulphur dioxide dissipates over time.
Winemakers can and do use sulphur dioxide at four stages of wine production – harvesting, crushing, fermentation and bottling.
Harvesting – sulphur dioxide is applied to inhibit an uncontrolled fermentation caused by wild yeasts.
Crushing – sulphur dioxide may be added to prevent wild yeasts from interfering with fermentation. Winemakers prefer cultured yeasts, which are sulphur dioxide resistant.
Fermentation – sulphur dioxide may be added at any time to stop or prevent malolactic fermentation. Fermenting yeasts naturally produce 10 and up to 30 mg/L, but the latter is rare.
Bottling – sulphur dioxide is added during bottling to prevent oxidation and an accidental fermentation in the bottle. Both are highly undesirable. Sweet wines are particularly prone, and some winemakers use large amounts to avoid both. In Germany winemakers like “sterile” bottling, which largely eliminates fermentation in the bottle.
Sulphur dioxide manifests itself in two forms – dissolved in wine (fixed) and volatile (free). The latter smells, the former affects flavour and can be tasted.
Generally, white and sweet wines are treated with sulphur dioxide. Sweet wines contain more sulphur dioxide. Red wines do not require sulphur dioxide as they contain naturally higher levels of natural sulphur dioxide and antioxidants.
Excessive oxidation ruins wine, controlled oxidation adds complexity, particularly to sherries, vin jaune and Madeiras.
Guest Writer – Hrayr Berberoglu E-mail or interested in his books?.
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Tags: Sulphur dioxide
Mark Ramos
May 5th, 2009 at 21:17
it kind of freaks me out to know that there is something toxic in the wine that I am drinking, but if I have never had a problem with it, I assume that ignorance is bliss! maybe I will stick to red wines from now on?
Emmick
May 10th, 2009 at 07:15
it certainly is a concern, bad for asthamatics too !
Emmicks last blog post..Double Blues run riot !!
Dave Brown
June 24th, 2009 at 02:55
Does that mean that it’s healthier to drink red wines? It’s a little scary to think about the fact that a toxin could be in the wine that I drink. Are there other preservatives added to most wines? Do you think organic wines have these same amount of sulfur dioxides added? Sorry I know that’s a ton of questions.
Matthew
August 19th, 2009 at 06:27
I guess I am one of those lucky ones that is not allergic to Sulpher Dioxide! I couldn’t imagine not being able to drink white or sweet wines. Might have to start drinking just red wines though. Kind of scares me about toxins being in wine!
.-= Matthew´s last blog ..Strength Training in 10 Minutes! =-.
ben
September 2nd, 2009 at 00:59
this is total and utter rubbish, you should state facts, not general musings.
“Red wines do not require sulphur dioxide as they contain naturally higher levels of natural sulphur dioxide and antioxidants”.
excuse me? they do not require so2? if you read this article, please do yourself and the wine industry a favour by taking it further and finding out what sulphur dioxide is, and that in wine it is COMPLETELY HARMLESS. if you think you are unlucky enough to be allergic try eating some dried fruit. sneeze? itch? no? theres more so2 in that fruit than in any bottle of wine.
Morten Pedersen
September 2nd, 2009 at 06:44
I do hope you are right with it when you say it is completely harmless because I do drink 1-2 bottles a week. BUT why is there a warning on the bottles saying that it contains: sulphur dioxide then? Can you tell me that?
Norman Rockwell Art
September 2nd, 2009 at 13:30
Maybe I am just sensitive or suggestible; but when I drink excess wine, I often get congested nasally. I usually blame it on excess sulfite consumption. Will I stop consuming wine because of this? Not on your life!
My research (just now on wikipedia) shows that SO2 is a toxin at high levels. Ben is correct; wine does not contain high enough levels of sulfites to be toxic. Not naturally or added by the winemaker.
Because I believe myself to be sensitive to sulfites, I have tried on occasion to find wine untreated with sulfites. I have yet to find a suitable botttle, ie none yet have tasted good to me.
I believe most of the better wine makers value their brand and product enough that they consider sulfites an insurance policy against unwanted fermentations. One winemaker friend actually had another (unwanted) fermentation in bottle in one of his varietals. It was a sweet rose wine. He had recently changed to a different, less expensive brand of sulfite and blamed the moving corks on that decision. He has since switched back to his original brand. We had to return several bottles of that wine for trade for different varietals. So you can see why winemakers utilize sulfites to stop the unwanted fermentation.
And, Morten, that warning is on the label because some people, like me, are sensitive to sulfites. Some are deathly allergic to some allergens. The warning is there as a warning to those individuals that they should exercise caution when consuming that product.
Thanks to the original poster for opening up this topic for discussion. Hyperbole aside, this is a matter all wine drinkers should explore and form their own opinions on.
.-= Norman Rockwell Art´s last blog ..Sep 1, The 1939 Norman Rockwell Santa, Extra Good Boys And Girls =-.
Morten Pedersen
September 2nd, 2009 at 14:13
Again thanks for the input. It has been interesting to read all about it.