Changes in Phenolic Acid and Isoflavone Contents during Soybean Drying and Storage

The changes in phenolic acid and isoflavone profile of soybean genotypes (Nidera 5909 RR and BMX Força RR) dried at different temperatures and stored for 12 months were investigated. In both cultivars, there was a reduction of the germination capacity and an increase of fungal incidence with the increase of drying temperature and storage time. Multivariate analysis of phenolic acids allowed for the differentiation among treatments. Cultivar Nidera 5909 RR, dried at 110 °C, showed an interaction with characters of greater relevance for differentiation, being influenced by the increase of bound coumaric, and syringic, and free-hydroxybenzoic, syringic, and coumaric acids. Multivariate analysis of isoflavones showed a strong affinity of the aglycone isoflavones (genistein, glycitein, and daidzein) within the Nidera 5909 RR cultivar at all drying temperatures and with BMX Força RR cultivar at the highest temperatures. These results indicate that the release and interconversion of isoflavone malonyl-β-glucosides and β-glucosides into aglycone forms are simultaneous reactions during storage.