Characterization of Vitamin B12 Compounds from Korean Purple Laver (Porphyra sp.) Products

Vitamin B-12 contents of various Korean purple laver products were determined with the microbiological vitamin B-12 assay method. Although a substantial amount (133.8 mu g/100 g) of vitamin B-12 was found in dried purple laver, seasoned and toasted laver products contained lesser vitamin B-12 contents (about 51.7 mu g/100 g). The decreased vitamin B-12 contents in the seasoned and toasted laver products, however, were not due to loss or destruction of vitamin B-12 during the toasting process. Silica gel 60 thin layer chromatography-bioautogram analysis indicated that all Korean laver products tested contain true vitamin B-12, but not inactive corrinoid compounds. In vitro gastrointestinal digestion experiments indicated that digestion rate of vitamin B-12 from the dried Korean purple laver was estimated to be 50% under pH 2.0 conditions (as a model of normal gastric function). These results suggest that Korean purple laver products would be excellent vitamin B-12 sources for humans, especially vegetarians.