Impact of Nitrogen and Elemental Sulfur on Formation of Volatile Sulfur Compounds during Fermentation of Pinot Noir Grapes

Abstract

The influence of yeast assimilable nitrogen (YAN) and elemental sulfur (S0) on the formation of volatile sulfur compounds (VSCs) during fermentation was investigated. Pinot noir fermentations were performed using Saccharomyces cerevisiae strain UCD522 or P1Y2 with an addition of 0, 5, or 15 µg/g elemental sulfur. H2S production during fermentation was measured using lead acetate tubes and additional VSCs measured by GC-PFPD. The addition of S0 resulted in H2S formation during alcoholic fermentation regardless of which yeast strain was used. H2S production was greater in fermentations performed by UCD522 with increasing amounts of S0 resulting in increased production of H2S. Higher S0 resulted in wines containing higher concentrations of methyl thioacetate and glutathione disulfide. Additional experiments examined the impact of nitrogen composition and S0. The addition of diammonium phosphate (DAP) resulted in an increase in H2S formation during fermentation whereas the addition of amino acids did not, whether S0 was added or not. Fermentations where DAP and S0 were both added produced a higher concentration of H2S compared to fermentations where S0 or DAP additions were made individually. VSCs in the wine were also impacted by the addition of nitrogen and/or S0 with the addition of S0 and nitrogen (DAP or amino acids) resulting in elevated concentrations of methyl thioacetate in the wines.