Chun Jiyeon, Kim Gyoung Min, Lee Kang Wook, Choi In Duck, Kwon Gun-Hee, Park Jae-Young, Jeong Seon-Ju, Kim Jeong-Sang, Kim Jeong Hwan
Div. of Applied Life Science, Graduate School, Inst. of Agriculture and Life Science, Gyeongsang National Univ., Jinju 660-701, Korea.
J Food Sci. 2007 Mar;72(2):M39-44. doi: 10.1111/j.1750-3841.2007.00276.x.
Four lactic acid bacteria (LAB), Lactobacillus paraplantarum KM, Enterococcus durans KH, Streptococcus salivarius HM and Weissella confusa JY, were isolated from humans and tested for their capabilities of converting isoflavone glucosides to aglycones in soymilk. Changes in growth, pH, and titratable acidity (TA) were investigated during fermentation at 37 degrees C for 12 h. After 6 to 9 h of fermentation, each population of 4 LAB reached 10(8) to 10(9) CFU/mL. The initial pH of 6.3 +/- 0.1 decreased while the TA of 0.13%+/- 0.01% increased as fermentation proceeded, resulting in the final range between 4.1 +/- 0.2 and 4.6 +/- 0.1 for pH and between 0.51%+/- 0.02% and 0.67%+/- 0.06% for TA after the 12 h of fermentation. The glucoside concentrations were significantly decreased in soymilks fermented with either L. paraplantarum KM, S. salivarius HM, or W. confusa JY with fermentation time (P < 0.05). L. paraplantarum KM was the best in percent conversion of glucosides to corresponding aglycones, resulting in 100%, 90%, and 61% hydrolysis of genistin, daidzin, and glycitin, respectively, in 6 h. Consequently, the aglycone concentrations in soymilk fermented with L. paraplantarum KM were 6 and 7-fold higher than the initial levels of daidzein and genistein, respectively, after 6 h of fermentation. Changes in the daidzin and genistin levels were not significant in soymilk fermented with E. durans KH. The rates of hydrolysis of glucosides varied depending on the species of LAB. Especially, L. paraplantarum KM seems to be a promising starter for bioactive-fermented soymilk based on its growth, acid production, and isoflavone conversion within a short time.
从人体中分离出四株乳酸菌（LAB），分别为植物源副干酪乳杆菌KM、耐久肠球菌KH、唾液链球菌HM和困惑魏斯氏菌JY，并检测了它们在豆浆中将异黄酮糖苷转化为苷元的能力。在37℃发酵12小时的过程中，研究了其生长、pH值和可滴定酸度（TA）的变化。发酵6至9小时后，4株乳酸菌的菌数均达到10⁸至10⁹CFU/mL。随着发酵进行，初始pH值6.3±0.1降低，而TA从0.13%±0.01%升高，发酵12小时后，最终pH值范围在4.1±0.2至4.6±0.1之间，TA在0.51%±0.02%至0.67%±0.06%之间。用植物源副干酪乳杆菌KM、唾液链球菌HM或困惑魏斯氏菌JY发酵的豆浆中，糖苷浓度随发酵时间显著降低（P<0.05）。植物源副干酪乳杆菌KM在将糖苷转化为相应苷元的转化率方面表现最佳，在6小时内分别使染料木苷、大豆苷和黄豆黄素的水解率达到100%、90%和61%。因此，用植物源副干酪乳杆菌KM发酵6小时后，豆浆中大豆苷元和染料木素的浓度分别比初始水平高6倍和7倍。用耐久肠球菌KH发酵的豆浆中大豆苷和染料木苷水平变化不显著。糖苷的水解率因乳酸菌种类而异。特别是，植物源副干酪乳杆菌KM基于其生长、产酸以及在短时间内的异黄酮转化能力，似乎是生物活性发酵豆浆的一种有前景的发酵剂。
