Yeasts and natural production of sulphites

During alcoholic fermentation yeasts naturally produce sulphur dioxide as a metabolic intermediate of the sulphate reduction pathway. Yeast strains can be categorized into low SO2 producers i.e. Saccharomyces cerevisiae var. ellipsoideus and high SO2 producers i.e Saccharomyces bayanus Sacardo. Certain yeast strains can produce up to 300 mg/L of sulphite during fermentation….. Extract from Research Results in Code of Best Practice for Organic Winemaking, produced under the EU FP6 STREP project ORWINE