HPLC-based quantification of elemental sulfur in grape juice

Abstract

Elemental sulfur is commonly used in vineyards as a fungicide to prevent diseases and protect grapevines.¹ The challenges of climate change are intensifying disease pressure, further increasing the reliance on sulfur use. Understanding the range of potential impacts of residual sulfur during the winemaking process is becoming increasingly important. For example, it is thought that sulfur residues can contribute to the formation of undesirable volatile sulfur compounds (VSCs) such as hydrogen sulfide (H₂S), and methanethiol (MeSH), which negatively affect wine quality.^2,3 Existing analytical methods to measure elemental sulfur in grape and wine samples are laborious and often require large volumes of samples. This study has developed a straightforward HPLC-DAD method for measuring elemental sulfur following a small-scale solvent-based extraction process. The method was subsequently employed in a study investigating the impact of residual elemental sulfur in grape juice, under low and high nitrogen conditions, on the formation of VSCs during fermentation and ageing.

References

[1] Thomas, C. S.; Boulton, R. B.; Silacci, M. W.; Gubler, W. D. The Effect of Elemental Sulfur, Yeast Strain, and Fermentation Medium on Hydrogen Sulfide Production During Fermentation. Am. J. Enol. Vitic. 1993, 44 (2), 211.

[2]Rankine, B. C. Nature, Origin and Prevention of Hydrogen Sulphide Aroma in Wines. Journal of the Science of Food and Agriculture 1963, 14 (2), 79–91. https://doi.org/10.1002/jsfa.2740140204.

[3] Jastrzembski, J. A.; Allison, R. B.; Friedberg, E.; Sacks, G. L. Role of Elemental Sulfur in Forming Latent Precursors of H2S in Wine. J. Agric. Food Chem. 2017, 65 (48), 10542–10549. https://doi.org/10.1021/acs.jafc.7b04015.