title: Occurrence of hydrogen sulfide in wine and in fermentation: influence of yeast strain and supplementation of yeast available nitrogen.
abstract: Hydrogen sulfide (H₂S) is a powerful aroma compound largely produced by yeast during fermentation. Its occurrence in wines and other fermented beverages has been associated with off-odors described as rotten egg and/or sewage. While the formation of hydrogen sulfide (H₂S) during fermentation has been extensively studied, it is the final H₂S content of wine that is actually linked to potential off-odors. Nevertheless, factors determining final H₂S content of wine have received little attention, and it is commonly assumed that high H₂S-forming fermentations will result in high final concentrations of H₂S. However, a clear relationship has never been established. In this report, we investigated the contribution of yeast strain and nitrogen addition to H₂S formation during fermentation and its consequent occurrence the resulting wines. Five commercial Saccharomyces cerevisiae wine yeast strains were used to ferment a Chardonnay juice containing 110 mg/l of YAN (yeast assimilable nitrogen), supplemented with di-ammonium phosphate (DAP) to increase YAN concentration to moderate (260 mg/l) and high (410 mg/l) levels. In contrast to the widely reported decrease in H₂S production in response to DAP addition, a non-linear relationship was found such that moderate DAP supplementation resulted in a remarkable increase in H₂S formation by each of the five wine yeasts. H₂S content of the finished wine was affected by yeast strain, YAN, and fermentation vigor. However, we did not observe a correlation between concentration of H₂S in the finished wines and H₂S produced during fermentation, with low-forming fermentations often having relatively high final H₂S and vice versa. Management of H₂S in wine through nitrogen supplementation requires knowledge of initial YAN and yeast H₂S characteristics.
authors.affiliation: The Australian Wine Research Institute, Post Office Box 197, Glen Osmond, Adelaide, SA 5064, Australia. maurizio.ugliano@awri.com.au
authors.forename: Maurizio
authors.initials: M
authors.lastname: Ugliano
authors.forename: Radka
authors.initials: R
authors.lastname: Kolouchova
authors.forename: Paul A
authors.initials: PA
authors.lastname: Henschke
mesh_terms: D005285:Fermentation; D005516:Food Microbiology; D006862:Hydrogen Sulfide / Q000032:analysis*; D009584:Nitrogen / Q000378:metabolism*; D009812:Odorants / Q000032:analysis; D010710:Phosphates / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D014920:Wine / Q000382:microbiology*
chemical_list: D010710:Phosphates; C024788:ammonium phosphate; D009584:Nitrogen; D006862:Hydrogen Sulfide