ORP in Wine

Hydrogen sulfide, H2S, is an undesirable compound produced during wine fermentation. Though colorless, hydrogen sulfide has a strong smell of rotten eggs. Even at concentrations lower than detectable by a human nose, hydrogen sulfide can contribute to a closed smell and taste, as well as contributing to formation of mercaptans and other undesirable compounds in the final product. Formation of hydrogen sulfide typically occurs during the primary fermentation when yeast activity is high. Copper sulfate is commonly added to remove H2S when high concentrations are detected.