Two-step fermentation to produce vitamin B12 containing beer using Propionibacterium freudenreichii and yeast

The growing focus on sustainable development is encouraging more people to adopt vegetarian diets and alternative protein sources, increasing the demand for natural sources of vitamin B12. Propionibacterium freudenreichii has been identified as a potent producer of vitamin B12 through fermentation processes. In this study, two distinct batches of beer were produced: one serving as a control comprising probiotic Saccharomyces boulardii CNCM I-745 and Saccharomyces cerevisiae SafAle™ US-05, and the other integrating these yeasts alongside P. freudenreichii DSM 20271. A two-step fermentation approach was adopted, with bacterial fermentation followed by yeast fermentation, to augment the vitamin B12 content in the beer. The application of this methodology resulted in successful enhancement of vitamin B12 levels in the beer, reaching 2.80 (±0.3) ng/ml, translating to 1.40 (±0.13) μg of vitamin B12 per 500-ml beer bottle. Over the course of an 80-day fermentation period, various parameters including cell counts, sugars, acids, ethanol, volatile compounds and vitamin B12 were monitored. Furthermore, a trained sensory panel was engaged to discern any perceptible differences between the two beer variants. The results suggest that the co-fermented beer exhibited minimal divergence in sensory attributes compared with the yeast-fermented counterpart, implying that the metabolite production by P. freudenreichii did not significantly affect the sensory profile of the beer. This study serves as compelling evidence that the natural fortification of beer with nutritionally significant levels of vitamin B12 can be achieved through fermentation processes involving P. freudenreichii . • Beer was naturally fortified with vitamin B12 using Propionibacterium freudenreichii. • Trained sensory panel found minimal taste differences in vitamin B12-enriched beer compared to control beer. • Yeast cells in co-fermented beer reached probiotic levels over 6 log CFU/ml.