Assertion: gypsum's amount | /r/HasProperty | fermented wine
Facets:
value: to produce traces of sulfurous acid
type: PURPOSE
Source sentences:
text: Small amounts of sulfur dioxide gas addition (or equivalent potassium metabisulfite addition) to fermented wine to produce traces of sulfurous acid (produced when SO 2 reacts with water) and its sulfite salts in the mixture, has been called "the most powerful tool in winemaking".