Interconversions of Isoflavones in Soybeans as Affected by Storage

Abstract

ABSTRACT: Conversions of isoflavones in soybeans under 4 conditions were investigated. Soybeans were stored in 84% RH, 30 °C for 9 mo and in 57% RH, 20 °C, cold (4 °C), and an uncontrolled ambient garage for 18 mo. Isoflavones were analyzed by HPLC. In 84% RH, 30 °C, the interconversion between aglycones and β‐glucosides was significant ( p < 0.001). The percentage of β‐glucosides and malonylglucosides in total isoflavones decreased from 99% to 3% in 9 mo. In contrast, the aglycones increased from 1% to 97%. In 57% RH, 20 °C, and ambient conditions, the glucoside forms increased with storage time, but malonylglucosides tend to decrease. In the 4 °C condition, isoflavone distribution had no significant ( p > 0.05) changes during storage.