Exploratory study on the occurrence and dynamics of yeast-mediated nicotinamide riboside production in craft beer

In this study, nicotinamide riboside (NR), a form of vitamin B3, and its precursors nicotinamide mononucleotide (NMN) and NAD+ were quantitated by a fluorometric assay in ten commercial craft beers and throughout the fermentation process of laboratory-scale beer. All tested beers from different commercial S. cerevisiae strains contained NAD+ (ranging from 1.10 μM to 17.80 μM). NR concentrations ranged from 0.48 to 3.25 μM, while the content of NMN was approximately 0.9 μM. NR and NMN were only present in beers produced with Saccharomyces cerevisiae strain US-05. Data from laboratory-scale beer productions using S. cerevisiae strain US-05 showed that the addition of hops [amarillo (alpha acid: 9.0%) (4 g/L) and centennial (alpha acid: 8.5%) (4 g/L) varieties] at the 9th day of fermentation significantly increased NR production up to 6.11 μM at the end of a typical fermentation of 21 days, and up to 11.42 μM at 45 days of fermentation. The rapid increase in NR formation only occurred if both hops and yeast were present, and the burst was also confirmed in fermentations trials performed with S. cerevisiae strain CBS1171T and by replacing wort with YPD medium. This study can serve as baseline for further research on yeast-hop interaction.