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

Abstract

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 μg VitB12/100 g in the BSG at lab scale. Finally, experiments were performed at 12 kg scale fermentation with a stabilized pH and resulted in 7.7 μg 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.