H₂S Production in Yeasts: Selection Methodologies and Risk Factors in Fermentation
Tiziana Nardi, from CREA Viticoltura ed Enologia, analyzes hydrogen sulfide production mechanisms in enological yeasts, presenting screening methodologies used for selecting low sulfur compound-producing strains.
This video was extracted from the masterclass on wine instabilities organised by Vinidea. You can access the full recordings at the following link:https://vinidea.it/en/product/wine-faults/
Technical Contents:
The presentation examines screening methodologies for H₂S production in yeasts: BiGGY agar differential medium (brown precipitate indicates high H₂S production), fermentation verification using lead acetate strips positioned in the gas phase of flasks to intercept H₂S carried by CO₂. Species comparison: Pichia membranifaciens (high production), Torulaspora delbrueckii, Metschnikowia and commercial Saccharomyces cerevisiae strains.
Analytical Methods:
Two-stage selection protocol: primary exclusion on BiGGY agar plates of strains with markedly brown coloration, secondary fermentation verification of strains with intermediate coloration. Fuchsin agar test for CO₂ production evaluation: high CO₂ production correlated with greater acetaldehyde production and consequent binding with sulfur dioxide, reducing its antimicrobial effectiveness.
Spontaneous Fermentations:
Analysis of specific risk in spontaneous fermentations: annual variability of microbial population with possible presence of high H₂S-producing strains. Management of transient reduction: aeration, copper addition, nutritional corrections.
Risk Factors:
Study of main factors inducing H₂S production in any strain: nitrogen deficiencies, nutritional imbalances, residual sulfur presence, fermentation stress and oxygen availability.
This video was extracted from the masterclass on wine instabilities organised by Vinidea. You can access the full recordings at the following link:https://vinidea.it/en/product/wine-faults/
