Formation of Hydrogen Sulfide from Elemental Sulfur During Fermentation by Wine Yeast

Abstract

The concentration of hydrogen sulfide formed from elemental sulfur was followed during fermentation by means of an ion electrode specific for sulfide ion. This method allowed hydrogen sulfide to be measured throughout the fermentation and to be measured more precisely than by chemical methods previously used. Hydrogen sulfide was detected in the fermentation only after about half of the sugar had been fermented; the concentration reached the highest value at the end of the fermentation. Generally, the hydrogen sulfide disappeared completely following the completion of fermentation. The concentration of hydrogen sulfide was found to be dependent upon the kind and the amount of elemental sulfur, the oxidation-reduction state of the medium, the ethanol concentration, and the physiological condition of the yeast. Direct contact of the yeast cell with sulfur particles seemed to be necessary. The reduction of the elemental sulfur was apparently a nonenzymatic chemical reaction caused by certain reducing compounds formed in the yeast cell during fermentation.