Production of Sulfur Dioxide-Binding Compounds and of Sulfur Dioxide by Two Saccharomyces Yeasts

¹ Agricultural College Department, Roseworthy. S. A. 5371. Australia.

The main SO₂-binding compounds in dry white wines are acetaldehyde, pyruvic acid and -ketoglutaric acid. The production of these three compounds by a strain of Saccharomyces cereviseae and by a strain of S. oviformis was investigated during the fermentation of grape juice containing graded amounts of SO₂. A strain difference was observed in that S. oviformis produced more of each compound than did S. cereviseae under comparable conditions. Higher initial levels of SO₂ resulted in higher SO₂-combining power of wines. Both acetaldehyde and pyruvic acid concentrations reached maxima and then decreased during fermentation by both yeasts. The -ketoglutaric acid concentration reached a maximum with each yeast, then subsequently decreased with S. cereviseae but remained constant with S. oviformis. S. oviformis produced between 35 and 76 ppm SO₂ during fermentation, whereas S. cereviseae produced no SO₂. Sulfur dioxide production was correlated with sugar utilization and was decreased by higher levels of SO₂ added to the grape juice.