Biofortification, metabolomic profiling and quantitative analysis of vitamin B12 enrichment in guava juice via lactic acid fermentation using Levilactobacillus brevis strain KU15152

Abstract BACKGROUND Chemical fortification and dose supplementation of vitamin B 12 are widely implemented to combat deficiency symptoms. However, in situ, fortification of vitamin B 12 in food matrixes can be a promising alternative to chemical fortification. The present study aimed to produce vitamin B 12 ‐rich, probiotic guava juice fermented with Levilactobacillus brevis strain KU15152. Pasteurized fresh guava juice was inoculated with 7.2 log CFU mL −1 L. brevis strain KU15152 and incubated for 72 h at 37 °C anaerobically. The antioxidants, total phenolic compounds, vitamin B 12 production, sugars, organic acids, pH and viable count were analyzed at 24, 48 and 72 h of incubation. The fermented juice was stored at 4 °C, and the changes in its functional properties were analyzed at 7‐day intervals up to 28 days of storage. RESULTS During fermentation, the bacteria cell count was increased from 7.01 ± 0.06 to 9.76 ± 0.42 log CFU mL −1 after 72 h of fermentation and was decreased to 6.94 ± 0.34 CFU mL −1 during storage at 4 °C after 28 days. The pH, total soluble solids, crude fiber, citric acid and total sugars decreased, while titratable acidity, total protein, antioxidants, phenolic compounds and lactic acid contents increased during fermentation. The fermented guava juice exhibited higher 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and 2,2′‐azino‐bis‐(3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS)) radical scavenging activities (85.97% and 75.97%, respectively) at 48 h of fermentation. The concentration of active vitamin B 12 in the sample reached 109.5 μg L −1 at 72 h of fermentation. However, this concentration gradually decreased to 70.2 μg L −1 during the storage period. During storage for 28 days at 4 °C, both the fermented and control guava juices exhibited a decline in antioxidant and phenolic compound concentrations. Furthermore, the addition of 20% honey and guava flavor enhanced the organoleptic properties and acceptability of fermented guava juice. CONCLUSION The value‐added fermented guava juice could be a novel functional food product to combat vitamin B 12 deficiency. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.