Donkor O N, Shah N P
School of Molecular Sciences, Victoria University, Werribee Campus, P.O. Box 14428, Melbourne, Vic 8001, Australia.
J Food Sci. 2008 Jan;73(1):M15-20. doi: 10.1111/j.1750-3841.2007.00547.x.
The study determined beta-glucosidase activity of commercial probiotic organisms for hydrolysis of isoflavone to aglycones in fermenting soymilk. Soymilk made with soy protein isolate (SPI) was fermented with Lactobacillus acidophilus LAFTI L10, Bifidobacterium lactis LAFTI B94, and Lactobacillus casei LAFTI L26 at 37 degrees C for 48 h and the fermented soymilk was stored for 28 d at 4 degrees C. beta-Glucosidase activity of organisms was determined using rho-nitrophenyl beta-D-glucopyranoside as a substrate and the hydrolysis of isoflavone glycosides to aglycones by these organisms was carried out. The highest level of growth occurred at 12 h for L. casei L26, 24 h for B. lactis B94, and 36 h for L. acidophilus L10 during fermentation in soymilk. Survival after storage at 4 degrees C for 28 d was 20%, 15%, and 11% greater (P < 0.05) than initial cell counts, respectively. All the bacteria produced beta-glucosidase, which hydrolyzed isoflavone beta-glycosides to isoflavone aglycones. The decrease in the concentration of beta-glycosides and the increase in the concentration of aglycones were significant (P < 0.05) in the fermented soymilk. Increased isoflavone aglycone content in fermented soymilk is likely to improve the biological functionality of soymilk.
该研究测定了商业益生菌在发酵豆浆中将异黄酮水解为苷元的β-葡萄糖苷酶活性。用大豆分离蛋白（SPI）制作的豆浆在37℃下分别用嗜酸乳杆菌LAFTI L10、乳酸双歧杆菌LAFTI B94和干酪乳杆菌LAFTI L26发酵48小时，然后将发酵后的豆浆在4℃下储存28天。以对硝基苯基β-D-吡喃葡萄糖苷为底物测定这些菌株的β-葡萄糖苷酶活性，并进行这些菌株将异黄酮糖苷水解为苷元的实验。在豆浆发酵过程中，干酪乳杆菌LAFTI L26在12小时时生长水平最高，乳酸双歧杆菌LAFTI B94在24小时时最高，嗜酸乳杆菌LAFTI L10在36小时时最高。在4℃下储存28天后，存活率分别比初始细胞数高20%、15%和11%（P<0.05）。所有细菌都产生β-葡萄糖苷酶，该酶将异黄酮β-糖苷水解为异黄酮苷元。在发酵豆浆中，β-糖苷浓度的降低和苷元浓度的增加具有显著性（P<0.05）。发酵豆浆中异黄酮苷元含量的增加可能会改善豆浆的生物学功能。
