What are sulfites and why are they used?
Sulfur dioxide (SO2) is used to protect the wine's character by inhibiting the growth of molds and bacteria and by stopping oxidation (browning) of the wine. In grape juice or wine, sulfur dioxide reacts with water molecules to form sulfites. A sulfiting agent can be added to foods and beverages in the form of sulfur dioxide (a gas) or as potassium bisulfite or metabisulfite (powders). In solution, all forms act the same way, releasing sulfur dioxide.
Is the addition of sulfites to wine a new procedure?
No, there is strong evidence that sulfur dioxide was used by the Egyptians and has been in regular use since Roman times. European winemakers have used sulfur dioxide to prevent wine spoilage for centuries.
Are there also "naturally occurring" sulfites in wines?
Yes, wine yeasts naturally produce up to 50 parts per million (ppm) of SO2 during fermentation. There are also naturally occurring sulfites in other foods. In addition, our own bodies produce about 1,000 mg of sulfite a day through normal biochemical processes.
When did the "Contains Sulfites" label become mandatory on wines in the USA?
In 1988, a Bureau of Alcohol, Tobacco and Firearms (ATF) ruling required all imported and domestic wines, beers and spirits to carry the label if they meet or exceed a threshold of 10 parts per million (ppm) sulfites. Because of natural sulfites, almost all wine falls under this ruling, regardless of whether sulfites have been added.
Why the concern?
The concern over sulfites in the United States arose with the use of extremely high levels of SO2 (1,000 to 3,000 ppm) on salad bars to prevent browning of fruits and head lettuce. This use of sulfites resulted in asthmatic reactions, some serious. In 1986 the FDA banned the use of sulfites on fresh fruits and vegetables while other foods and beverages must now be labeled if they contain sulfites, even those which contain very low levels.
What percentage of the population do sulfites affect?
According to Dr. Herbert Kaufman MD, Associate Clinical Professor of Medicine at U.C. San Francisco, the reaction is a chemical sensitivity found in an extremely small percentage of the population. The majority of sulfite-sensitive individuals are asthmatic, but represent less than 3% of all asthmatics.
What is the sulfite level in Gray Monk Wines?
Our normal range is 60-70 ppm for white wines and 30-40 ppm for red wines. Wines actually need one of the lowest levels of sulfites to ensure stability. Because of wine's alcohol content, naturally high acidity and low pH, lower levels of SO2 need to be added to achieve stability.
How does this level compare with other foods?
According to Dr. George York of the Food Science Dept. at U.C. Davis, dried fruit, such as apples and apricots, are typically packaged with 500 to 1,000 ppm SO2.
Gray Monk Wines have sulfite levels that are among the lowest in the industry. How are the levels kept low and stability insured?
- using only the highest quality fruit, free of molds.
- processing and crushing immediately after the grapes are picked.
- conducting a long cool fermentation in tanks so the CO2 (carbon dioxide) produced during the fermentation blankets and protects the wine.
- careful monitoring of SO2 levels and judicious SO2 additions only when necessary.
- nitrogen sparging of bottles and vacuum corking at bottling to decrease oxidation potential.