Determination of vitamin B₁₂ content and identification of vitamin B₁₂ compounds in commercially available malted rice and bettara-zuke (Japanese radish pickled in malted rice) products

Abstract

While plant-derived foods do not contain vitamin B₁₂, some fermented plant-derived foods contain small amounts of vitamin B₁₂. However, it is unknown whether bettara-zuke and malted rice, which are fermented plant-derived foods using Aspergillus oryzae, contain vitamin B₁₂ compounds. Therefore, we determined vitamin B₁₂ content in bettara-zuke and malted rice using high-performance liquid chromatography after immunoaffinity purification of vitamin B₁₂ extracted from them. Then, we identified vitamin B₁₂ compounds contained in the purified samples using liquid chromatography-tandem mass spectrometry. The results showed that bettara-zuke and malted rice contained small amounts of vitamin B₁₂ and that the vitamin B₁₂ compound contained in them was physiologically active vitamin B₁₂. This study is the first to report that fermented plant-based foods which are made using koji mold, contain trace amounts of physiologically active B₁₂.