Comparison of crude prolamins from seven kidney beans (Phaseolus vulgaris L.) based on composition, structure and functionality.

Ethanol protocol, two-step protocol and enzymatic extraction were used to extract prolamins from seven kidney beans (P. vulgaris L.) compared with Osborne protocol. 70-80% (v/v) ethanol concentrations were beneficial to the extraction, and two-step protocol was conducive to higher prolamin content. Varied protein subunits were observed in electrophoresis profiles, and further differences in composition were identified by LC-MS/MS while potential functions were annotated. Stronger hydrophobicity was found with prolamins enrichment from light speckled kidney bean (LSKB), black speckled kidney bean (BSKB), and red kidney bean (RKB), which was negative correlation with α-helix content based on the principal component analysis (PCA). The crude prolamins from the two kinds of white kidney beans possessed higher sulfhydryl and exhibited better water holding capacity (WHC), while higher oil absorption capacity (OAC) was observed in LSKB, BSKB, and RKB. Compared with zein, kidney bean prolamins could be used as food packaging materials due to hydrophobicity.