Browsing by discipline "Food Science (Food Chemistry / Cereal Technology)"

To acquire sufficient amount of vitamin B12 (2-3 ?g/day), humans mostly consume animalderived foods in their diet, making vegetarians and vegans highly susceptible to vitamin B12.deficiency. Although sufficient vitamin B12 intake can also be met by consuming fortified foods and vitamin B12 supplements, there is an increasing trend to consume natural and food grade products rather than supplements in tablet form. However, plant-based fermented foods that contain naturally synthesized vitamin B12 are limited. This study therefore aimed to investigate the requirement of different precursors in the biosynthesis of vitamin B12 in optimal media conditions and then in cereal matrices using strains of Propionibacterium freudenreichii. Vitamin B12 was produced by three selected P. freudenreichii strains (strain 1, 2 and 3) in supplemented whey permeate (SWP) medium, 30% w/v barley malt matrix and 6% barley flour matrix. The additions of 5 mg/L cobalt chloride, 15 mg/L DMBI, 15.05 mg/L riboflavin and 3.29 g/L nicotinamide were investigated. The effects of three different time points (0, 72, 144 h) in adding riboflavin and nicotinamide were also investigated. Depending on the type of precursors and the timing of adding the precursors, six conditions were tested in the SWP medium, while three conditions were tested in the cereal matrices. After extraction in the presence of sodium cyanide, vitamin B12 was then quantified by microbiological assay (MBA) and ultra high-performance liquid chromatography (UHPLC). The two-stage fermentation of 72-hour anaerobic/96-hour aerobic fermentation led to high vitamin B12 yields with maximum production of 2.20 ?g/mL and 1.41 ?g/g produced in the SWP medium and the barley malt matrix, respectively. Depending on the type of precursors added in the culture samples, the capacity of the P. freudenreichii strains in vitamin B12 production varied. The strain 3 produced maximum vitamin B12 yields with the addition of riboflavin and nicotinamide at 0 h. With the vitamin B12 amount achieved in the fermented cereal matrices, this study successfully demonstrated the promising possibilities to enrich plantbased foods with vitamin B12 through in situ fermentation.