Phenolic and saponin profile in grains of carioca beans during storage

Abstract

The objective of this study was to evaluate the behavior of slow and fast-darkening carioca beans during storage, and the profile of phenolics and saponins, aiming to identify which compounds may be involved in the browning process of the integument of these grains. Cultivars Madreperola and Dama presented the lowest total color difference (ΔE) and the highest luminosity (L*) values during storage time indicating to be slow-darkening cultivars. In contrast, the cultivars Notavel and Imperador rapidly darkened with storage time, evidenced by the highest ΔE and lowest L*. Regarding the content of phenolic during storage, it was observed a reduction for free phenolics in fast-darkening beans and the maintenance/increase in slow-darkening beans. In the PCA of the phenolic profile, Notavel and Imperador were similar, differing from Dama and Madreperola, indicating that fast-darkening grains have similar phenolic profile. The OPLS/DA indicated that aged grains from bright beans had more kaempferol than darker beans. For saponins, the cultivars Imperador and Notavel presented higher content of Soyasaponin Bd, which might be related to the darkening process. Besides, kaempferol was found at higher concentrations in slow-darkening aged grains and can be a chemical marker of darkening in carioca beans.