Abstract
High-gravity beer fermentation can increase yeast stress and promote sulfur compound formation, which may cause undesirable aroma defects if not properly controlled. This study investigates yeast-derived sulfur compound control during high-gravity beer fermentation. Controlled fermentations were conducted using elevated wort gravity under fixed yeast strain, pitching rate, oxygenation, temperature, and nutrient conditions. Hydrogen sulfide, sulfur dioxide, methanethiol-related notes, yeast viability, amino nitrogen uptake, sugar utilization, ethanol formation, attenuation, pH reduction, and sensory quality were monitored. The results show that nitrogen deficiency and late-stage ethanol stress increased sulfur compound formation, especially when yeast vitality declined. Balanced nutrient supplementation and adequate oxygenation reduced hydrogen sulfide release and improved fermentation completion. Excessive nutrient addition, however, increased by-product variability and altered flavour balance. The study demonstrates that sulfur control in high-gravity brewing depends on matching yeast nutrition, oxygen availability, and stress management. Proper process control improves flavour cleanliness and fermentation reliability.