Analysis of a Special Sulphite-Producing Yeast Starter after Fermentation and during Wine Maturation

In the present study, we investigated the extent to which specific sulphur dioxide-producing wine yeasts produce SO2 during alcoholic fermentation and whether the SO2 they produce is sufficient to prevent oxidation during wine storage. Fermentation was carried out at 12 °C and 20 °C. After inoculation with yeast, the evolution of free and total sulphurous acid concentrations, acetaldehyde concentrations (11.6–46.9 mg L−1) and total polyphenol concentrations (137.4–244.7 mg L−1), including leucoanthocyanin and catechin concentrations (leucoanthocyanidin: 8.5–75.1 mg L−1; catechin: 70.8–115.4 mg L−1), were investigated during the storage of fermented wines. The amount of free sulphur dioxide was measured between 5 and 10 mg L−1. Total sulphuric acid ranged from 6 to 22 mg L−1, taking into account the results of the three years studied. The aim of our tests was to observe whether the use of sulphur-producing yeasts during the ageing of fermented wines showed any benefit. The results of all three vintages tested showed that neither the 12 °C nor the 20 °C fermented batches showed any advantage in using sulphur dioxide-producing yeasts. Our results show that there is no clear evidence that the yeast produces sufficient sulphur dioxide during fermentation and that there is no clear demonstrable benefit from its use.