Modulating conversion of isoflavone glycosides to aglycones using crude beta-glycosidase extracts from almonds and processed soy.
Ahn-Jarvis JH, Teegarden MD, Schwartz SJ, Lee K, Vodovotz Y
Food Chem 237 685-692 12/15/2017
Food processing alters the physicochemical state of soy which can enhance chemical and enzymatic conversion of isoflavones to their aglycone forms. This study investigated the role of ß-glycosidase from processed soy-ingredient mixture (SIM) or almonds, and examined the impact of isoflavone composition in mediating conversion to aglycones. ß-Glycosidase activity was quantified using p-nitrophenol-ß-d-glucopyranoside and SIM isoflavone extracts. Almond ß-glycosidase activity was significantly (p<0.001) reduced after roasting (99% reduction) or steaming (97% reduction) compared to raw almonds. SIM ß-glycosidase activity, however, increased, with steaming by 66% (p<0.001) and with roasting by 52% (p=0.022), compared to raw SIM. After incubation with ß-glycosidase, percentage of aglycone (total aglycone/total isoflavones) in SIM isoflavone extracts increased significantly in raw (35%), fermented (48%), roasted (88%) and steamed (91%) SIM, compared to their initial (~5%) compositions. Manipulation of ß-glycosidase activity and isoflavone composition can be used to modulate aglycone content in soy food products.