Molecular sulphur dioxideis the most affective form involved in both the reduction ofoxidation reactionsandmicrobial activityin wine.

The recommended level of molecular SO₂for red wines is 0.5 mg/L (ppm); for white wines is 0.8 mg/L (ppm); and for dessert wines is up to 1.5 mg/L (ppm). You can use this calculator to determine how much Free SO2 is required to protect your wine, based on its pH. Free SO₂over 50 mg/L (ppm) can be tasted and detect in nose of the wine.