In situ fortification of protein-enriched brewer's spent grain with vitamin B12 by fermentation with Priestia megaterium and Propionibacterium freudenreichii

Meat is an important protein source in the human diet; however, the consumption of animal proteins needs to be reduced. Plant-based foods naturally lack cobalamin, vitamin B12 (VitB12), an essential vitamin in the human diet. Brewer's spent grain (BSG) is a side stream available in large volumes that was chosen as a substrate for food-grade VitB12-producing microorganisms. VitB12-producing microorganisms were identified in the scientific literature and selected to study in situ production of VitB12 in a protein-enriched (53%) BSG. A first screening was performed using Propionibacterium freudenreichii and Priestia megaterium (formerly known as Bacillus megaterium) ) strains. Further optimisations were exploited to increase the BSG content further and resulted in levels of up to 21 mu g VitB12/100 gin the BSG at lab scale. Finally, experiments were performed at 12 kg scale fermentation with a stabilized pH and resulted in 7.7 mu g VitB12/100 g BSG, indicating the potential of in situ fortification of BSG with VitB12 by fermentation with P. freudenreichii. . Overall, it was found that the VitB12-fortified BSG could serve as a relatively inexpensive plant-based source of VitB12-fortified protein for food and feed applications. This study shows that fermentation offers opportunities to fortify (protein-enriched) BSG or other BSG derivatives with VitB12.