Vitamin B12 Activity in Miso and Tempeh

The USP microbiological assay with L. leichmannii, ATCC 7830, was used to determine vitamin B₁₂ activity in light rice miso, dark rice miso, barley miso, tempeh and tempeh burger. Unpasteurized misos were found to have the highest B₁₂ content, averaging 0.21 μg/ 100g. Vitamin B₁₂ activity in miso ranged from a high of 0.25 μg/ 100g in barley miso to a low of 0.15 μg/100g in light rice miso. Pasteurized tempeh contained 0.12 μg vitamin B₁₂ per 100g food. Tempeh burger contained 0.06 to 0.11 μg vitamin B₁₂ per 100g food. The variation in vitamin B₁₂ activity found in these products may be due to different conditions used or produced during fermentation. Collaborative studies are needed and assessment of vitamin B₁₂ pseudoform activity before these foods can be considered a source of vitamin B₁₂.