Determination and characterization of vitamin B12 in the muscles and head innards of edible shrimp

We determined the vitamin B12 content in both the muscles and head innards of various shrimp species [Argis lar (Owen, 1839); Togezako shrimp, Argis toyamaensis (Yokoya, 1933); Pandalopsis japonica, Balss, 1914; Pandalus eous Makarov, 1935] using a microbiological assay based on Lactobacillus delbrueckii subsp. lactis ATCC7830. Approximately 2–4 µg vitamin B12/100 g wet weight—a considerable amount—was detected in shrimp muscles. The shrimp head innards contained significantly higher levels of vitamin B12 (~ 12–33 µg/100 g wet weight). Commercially available shrimp-innard products contained ~ 30 µg vitamin B12/100 g wet weight. We purified vitamin B12 compounds from the extracts of shrimp muscles and head innards using an immunoaffinity column. The muscle extract contained only one corrinoid compound, which was identified as vitamin B12 using liquid chromatography–electrospray ionization/tandem mass spectrometry, whereas the shrimp head innards contained three corrinoid compounds, which included large amounts of vitamin B12 and two smaller amounts of vitamin B12-d-monocarboxylic acid and tentatively identified vitamin B12 dicarboxylic acids.