Comparing Liquid and Dried Yeast: Fermentation Performance and Flavor Stability over Multiple Generations

Abstract: Advancements in dried yeast quality have led to its widespread use in beer production. However, its impact on fermentation performance and flavor quality over multiple repitching cycles remains an area of study. This research examines how drying treatments influence yeast metabolism and fermentation dynamics during anaerobic adaptation across serial repitching.

Fermentations (150 L) were conducted using Saccharomyces pastorianus (LalBrew Diamond), with initial pitches from either liquid or dried yeast. The study assessed how these initial conditions affected fermentation performance over successive repitching cycles. Wort consisted of 80% pale lager malt and 20% light Munich malt, targeting a final alcohol content of 5% ABV. Prior to inoculation, all batches were aerated to ~10 mg/L dissolved oxygen.

Fermentations were monitored for changes in gravity, pH, organic acids, esters, higher alcohols, yeast concentration, viability, and budding index. Finished beer quality was evaluated through sensory and instrumental chemical assessments. Following each fermentation, yeast was harvested and repitched for a total of four generations (Generation 0 through Generation 3) for both yeast forms.

Initial fermentations showed notable differences between liquid and dried yeast in sensory and analytical profiles. However, after the first repitching, dried yeast stabilized fermentation performance more quickly and resulted in greater consistency across subsequent generations. Sensory analysis found no significant differences in flavor or aroma between yeast forms after the initial fermentation cycle. These findings suggest that dried yeast supports stable fermentation across multiple generations, reducing costs and increasing operational flexibility in breweries.