Structural, physicochemical and in vitro digestibility of white kidney bean protein-corn starch complexes under various heat treatments

The presence of exogenous protein can delay starch digestion. However, systematic studies on the effects of protein on starch digestion under various heat treatments still need to be completed. In this study, the effects of exogenous protein and heat treatments on corn starch digestibility were investigated. Molecular docking simulation was used to assess white kidney bean protein's (KBP) effect on α-amylase. Compared to corn starch, the resistant starch (RS) content in the physical mixture with KBP increased from 5.16% to 12.65%. Heat-moisture and annealing treatments further boosted RS to 19.74% and 18.74%. Dry heat increased digestibility, but KBP mitigated this. Heat treatments encouraged protein encapsulation of starch, forming complex aggregates. The introduction of KBP alleviated the effect of heat treatment on amylose content, improved the thermal stability of starch, protected starch granules from shear damage, and inhibited starch gelatinization and short-term retrogradation. These findings advance KBP's role in starch digestion and suggests its potential in low glycemic index foods.