Abstract
Vitamin B_<12> content in mild drastically decreased during fermentation by Lactobacillus helveticus B-1 occasionally used for production of a commercial yogurt. When vitamin B_<12> was added to mild prior to the fermentation, the maximal decrease occurred by addition of 10〜50 ng/ml and more than 90% of B_<12> compounds was unextractable from the fermented milk by a conventional KCN extraction method. However, the vitamin B_<12> content in fermented milk was partly recovered by treatment with pepsin alone or pepsin and ultrasonication.
