All wines contain at least
some small amount of sulfites. They are a natural result
of the same fermentation process that turns grape juice
into alcohol. Even wines that have not had any sulfites
added during the winemaking process contain some amount
of sulfites. Sulfur dioxide (SO2) is used by winemakers
to keep freshly pressed must from spoiling. It keeps down
the activities of native yeast and bacteria and preserves
the freshness of the wine. Modern technology has allowed
the use of significantly less sulfur than was used in the
past but some is necessary to make a stable wine.
Regulations in the United States
require that domestic and imported wines carry warning labels
if they have sulfites in excess of 10 parts per million.
Wines that have less than 10 parts per million are not required
to carry the "Contains Sulfites" label but they still contain
sulfites in some level.
