Molecular SO₂ is the active form against microorganisms and unwanted bacteria. The recommended level of molecular SO₂ for red wines is 0.5ppm (mg/L), for white wines is 0.8ppm (mg/L) and desert wines is up to 1.5ppm (mg/L) . You can use this table to determine how much Free SO₂ is required to protect your wine, based on its pH. Free SO₂ over 50ppm (mg/L) can be tasted and detect in nose of the wine.