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KMID : 0381019820150030202
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Korean Journal of Nutrition
1982 Volume.15 No. 3 p.202 ~ p.211
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A Modification of A Microbiological Assay of Vitamin B_(12) In Fermented Vegetables
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Lim Sook-Ja
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Abstract
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A modification of a microbiological assay of vitamin B12 was made and used to determine the vita-min levels during kimchi fermentation. A cyanide-buffer solution of pH 6.0 replaced the metabisufitebuffer specified in the A.O.A.C. method. The vitamin B,, activity was decreased by blending kimchi samples for 5 minutes and retained the activity by steaming for 10 minutes before blending. The alkali hydrolysis of kimchi at pH 12.0 for 30 minutes at 121C was sufficient to destroy the vitamin B1z and permit the detection of analogs with the same assay organism. Vitamin B1S leached a maximum of 47 ng/100 g during the fermentation of kimchi 15 4C. Inoculation of the kimchi with Propionibacterium shermanii (ATCC 13673) increased the vitamin production to a maximum of 102 ng/100 g at 1 week of fermentation. Soy flour (0.5%) or beef extract (0.05%), which were regarded as protein sources, added to the inoculated kimchi further increased the vitamin B12 activity to 197 and 203 ng/100 g.
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