“Dear Paul, I have heard that sulfites are used as preservatives in wine. I am inclined to be a natural food enthusiast and avoid preservatives. I receive conflicting answers to the sulfite story. Some say it is a natural product in wine, and others say it is added. Which is it?”
– W.O.; Bakersfield
The answer is dual. Yes, it is a natural by-product of wine. And yes, it is also added. From the time we started using wood barrels for storing or ageing wine, we discovered that we had to keep these barrels clean. When a barrel was empty, it had to be sterilized before the next use. To do this, the process of burning sulfur in the barrel was invented. The sulfur fumes sterilized the wood surface, and prepared the barrel for the next batch of wine. By trial and error, chances are we discovered that barrels which had been sulfured more thoroughly, preserved the wine better. Any traces of the sulfuring process must have been responsible. The by-products of the sulfur during burning created certain chemical entities that prevented the spoiling of the wine.
One of the ways wine spoils is oxidation. Air, which contains oxygen, attacks some of the natural organic components of wine, and oxidizes them. The flavor of the wine starts developing a “burnt” taste, as in sherry. Sherry is made by a controlled, desirable, form of oxidation! In our table wines, this is an undesirable characteristic. The presence of the byproducts of sulfur, in the form of sulfites, or sulfur dioxide gas prevents this oxidation. These compounds are antioxidants.
So, we use bisulfites or sulfur dioxide gas to prevent the oxidation of wine. We have for hundreds of years and it is a part of the winemaker’s tools.
Now, there are traces of sulfites in wine that naturally occur. Sulfur is a common element, and exists in organic combination in some proteins and other molecules in nature. The interplay of chemical reactions that occur in fermentation and maturation include the sulfur element as a natural product, but certainly not enough to act as an antioxidant.
We consume minimal amounts of sulfur compounds and sulfites in our daily diet. For the normal person, it seems that there is no problem with the ingestion of limited amounts of sulfites.
The problem lies in the quantity. If you are allergic to sulfites, or if you have asthma, sulfites in any quantity would be something you want to stay away from. Sulfites are used in food products too; particularly to avoid the browning of vegetables and fruits. People who have these conditions should be very careful with restaurant food.
Recent federal laws require any wine that has more than 10 part per million of sulfites to say so on the label. Practically all the wine produced now has more than that much, and as soon as new labels are printed by the wineries, the legend “contains sulfites” will appear on the labels. The average amount in wine is 200 parts per million, with the maximum allowable of 350 parts per million.
A little confusing? The final analysis might be that if you have not had a problem with allergy, then you could ignore the subject. If you are the allergic type, then be very careful, and watch out for symptoms of problems and consult you physician.