61C-23 |
Characterization of fermented soymilk with Bifidobacterium Int-57 |
K. S. JEON and I. K. Hwang. Food and Nutrition, Seoul National University, College of Human Ecology, Department of Food and Nutrition, San 56-1, Shillim-Dong, Kwanak-Ku, Seoul, 151-742, South Korea The isoflavone glycosides are hydrolyzed by b-glucosidase from gut microbes to the bioactive aglycones. However, the specific bacteria from the human intestinal tract that are involved in the metabolism of these compounds are not known. This study was undertaken to develop a fermented soymilk which contains isoflavones in the more bioactive aglycone form using the Bifidobacterium strain. The pH was measured with a pH meter(DP-215M, Dong Woo Medical, Seoul, Korea) and titratable acidity was determined by titration with 0.1N NaOH solution. Isoflavones analysis was performed by reversed-phase HPLC (HP 1090 Series ¥±, Hewlett Packard Co., Waldbronn, Germany). The b-glucosidase activity was assayed by determining the rate of hydrolysis of p-nitrophenyl-b-glucopyranoside. After 12 h of fermentation, the viable counts of Bifidobacterium sp. Int-57 in all the soymilks reached a level of more than 108 cfu/§¢, which was then maintained. The pH of soymilks started to decrease rapidly after 6 h of fermentation and leveled off after 18 h. The titratable acidity and b-glucosidase activity of soymiks increased over the fermentation period. The isoflavone glycosides, daidzin, glycitin and genistin, in soymilks were hydrolyzed completely in the relatively short fermentation time of 18 h. These results show that Bifidobacterium sp. Int-57 can be used as a potential starter culture for developing fermented soymilk which has completely hydrolyzed isoflavone glycosides.
Session 61C, Food Microbiology: General I
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