Why Do We Need Potassium Metabisulfite in Wine?
Winemakers use sulfur dioxide (Potassium Metabisulfite) at various stages of the winemaking process because:
It stabilizes the wine (preventing it from turning to vinegar or deteriorating from oxygen exposure).
It safeguards a wine's flavor.
Helps to stop fermentation of unwanted microorganisms (wild yeast)
It helps to prevent oxidation
Sulfur dioxide inhibits yeasts, preventing sweet wines from refermenting in the bottle. It’s an antioxidant, keeping the wine fresh and untainted by oxygen. Despite these magical properties, winemakers try to use as little sulfur dioxide as possible because many of them share a belief that the less you add to wine, the better.
Actual sulfite levels in wine range from about 30 to 150 parts per million (about the same as in dried apricots); the legal max in the United States is 350. White dessert wines have the most sulfur — followed by medium-sweet white wines and blush wines — because those types of wine need the most protection. Dry white wines generally have less, and dry reds have the least due to their tannins which act as a preservative.
Design2Brew recommends the use of sulfites in all homemade wines. Adding sulfites to your wine is easy. A good rule of thumb is to add ¼ teaspoon per 5-6 gallons each time you: first start your wine (not in kit wines because they already contain your initial dose), rack/transfer it (wine kits provide this dose), and bottle the wine (the sulfites are not included in wine kits). A more detailed discussion on sulfites can be found on Winemaker magazine’s Website, www.winemakermag.com.