Volatile Sulfur Compounds: Incidence and Factors Affecting Their Formation in California Wines

In this grant period, we have continued the analysis of hydrogen sulfide formation among 30 different yeast strains. The scope of this work makes it very long term, but it is essential to analyze a collection of wine strains rather than one or two in order to define the factors responsible for hydrogen sulfide formation. Most importantly, we are interested in defining the genes that lead to a reduction in hydrogen sulfide formation. Preliminary data suggests that these genes are dominant, that is, will convert a high producer of H2S into a low producer in single copy. This means that the gene can be introduced into any wine strain and result in reduced production of H2S. Initial studies indicate that the levels of sulfite reductase are similar across the wine strains used in this study, consistent with recent results presented by the Australian Wine Research Institute for a much smaller set of strains.