Molecular analysis of yeast population dynamics: Effect of sulphur dioxide and inoculum on must fermentation

The effects of sulphur dioxide and a commercial starter inoculum on yeast population dynamics have been analysed by a molecular approach. Yeast identification from fermenting Carinyena grape musts was performed by RFLP's of mtDNA and rRNA-coding DNA. As expected, the use of a commercial inoculum speeded up the start of fermentation, while SO 2 addition limited the development of non- Saccharomyces species. However, this effect was also observed with yeast inoculation. Further analysis of population dynamics could lead to a recommendation for the reduction of the dosage of SO 2 by the addition of appropriate inoculum of yeasts in the must. Furthermore, the timing of inoculum addition could be modified to allow a proper contribution of non- Saccharomyces species. Molecular biology analysis of population dynamics could provide a tool to efficiently reduce the dosage of SO 2 and adjust the timing of inoculum addition.