Sulfites are a group of chemical compounds that contain the sulfite ion (SOï¿½32- for those science buffs among us). They occur naturally in wine in low levels as byproducts of the complex fermentation reactions that transform grape juice into wine. Because of this, all wines essentially contain sulfites.
Most of the sulfites in wine, however, are added. As wine interacts with air it naturally oxidizes, often causing unwanted aging, discoloration, and even spoilage. To avoid these problems, winemakers almost always introduce additional sulfitesï¿½usually sulfur dioxide, SOï¿½ï¿½ï¿½ï¿½2ï¿½to wine to prevent such oxidation, especially in white wines that lack many of the natural preservatives that red wines gain from their contact with grape skins. Sulfites in wine are practically undetectable outside the laboratory in most wines (with the exception of young whites at the beginning of the winemaking process, in which the sulfur odor disappears long before the wineï¿½s release). Sulfites also provide an additional benefit by protecting the wine from unwanted bacteria. Because of all of these benefits of sulfites, sulfite-added wines can age for years while low sulfite wines usually have a shelf life of only a few months.
In America, law requires wines with sulfite levels over 10 ppm (parts per million) to carry warning labels (lower than the sulfite levels of many warning-free foods such as dried apricots). European and Southern Hemisphere wines, on the other hand, are subject to different sets of laws and will often not sport sulfite warnings on their labels despite having similar or even higher sulfite levels.
But why all the hoopla in the first place? While most people can consume low levels of sulfites like those in sulfite-added wines, some people, estimated by the FDA at around .4% of the population, have allergic or asthmatic reactions to sulfites even in relatively low levels. Even among those with asthma, according to research done by allergist and clinical immunologist Dr. Vincent Marinkovich, only about one in twenty has any significant reaction and low-level sulfite intake of sulfite-added wine presents no risk to 99.75% of the population.
While sulfites can cause headaches, hives, or cramps in hypersensitive people, medical research suggests that another compound in red wines and not sulfites might be the cause of symptoms among a very small segment of the population. Before attributing headaches to sulfites, someone who suspects to have a sulfite allergy might want to see if a handful of dried apricots triggers the same reaction.
Organic wines may offer an alternative for hypersensitive individuals. According to the Organic Wine Company, a company that imports organic French wines, states that organic wines contain sulfites at levels around 40ppm, about half of the non-organic average of about 80 ppm. Israelï¿½s Bashan Winery exclusively produces organic kosher wines with no sulfites added, available only in Israel.