Phenolic compounds profile by UPLC-ESI-MS in black beans and its distribution in the seed coat during storage

Abstract

Hard to cook phenomenon results from inadequate post-harvest storage of the bean associated with the microstructure and changes in seed color and texture. The aim of this study was to evaluate the physical and chemical properties, identify the phenolic compounds and their relationship with the black bean seed coat microstructure during 270 days at 30 °C and 70% r. h. The water absorption capacity decrease to 12.19% that induced changes in seed texture observed by increasing the hardness from 5.42 to 19.96 N. A total of 37 compounds were identified by UPLC-ESI-MS and the changes in phenolic profile during storage period contribute to the seed coat color saturation. The identification of flavonoids, hydroxybenzoic and hydroxycinnamic acids, as well as distribution of condensed tannins in the seed coat, the changes in physical properties evidenced by seed darkening and hardening contribute to the seed coat impermeability.

Keywords: Black bean; Darkening; Hardening; Phenolic compounds; Post-harvest storage; Seed coat microstructure.