Characterization of vitamin B₁₂ compounds from traditional fermented Japanese seafoods

This study identified vitamin B₁₂ compounds in traditional fermented Japanese seafoods, such as heshiko made with a mackerel, kusaya made with a flying fish, Akazukuri-shiokara made with a squid, and funazushi made with a crucian carp, using reversed-phase high-performance liquid chromatography and liquid chromatograph–tandem mass spectrometry. The vitamin B₁₂ content of these fermented seafoods was approximately 4–13 µg/100 g wet weight, indicating that vitamin B₁₂ is the predominant corrinoid in all seafoods tested. However, kusaya contained approximately 8% of inactive cobamides such as 2-methyladenylcobamide and 2-methylmercaptoadenylcobamide. In conclusion, these traditional fermented Japanese seafoods can be a source of vitamin B₁₂.