Interconversions of isoflavones in soybeans as affected by storage

Conversions of isoflavones in soybeans under 4 conditions were investigated. Soybeans were stored in 84% RH, 30 degreesC for 9 mo, and in 57% RH, 20 degreesC, cold (4 degreesC), and an uncontrolled ambient garage for 18 mo. Isoflavones were analyzed by HPLC. In 84% RH, 30 degreesC, the interconversion between aglycones and beta-glucosides was significant (p < 0.001). The percentage of beta-glucosides and malonylglucosides in total isoflavones decreased from 90% to 3% in 9 mo. In contrast, the aglycones increased from 1% to 97%. In 57% RH, 20 degreesC, and,ambient conditions, the glucoside forms increased with storage time, but malonylglucosides tend to,decrease. In the 4 degreesC condition, isoflavone distribution had no significant (p > 0.05) changes during storage.