Synergistic effect of pH-shift and controlled heating on improving foaming properties of pea vicilin and its adsorption behavior at the air-water interface

In this study, the impact of pH-shift (PV-pH), controlled heating (PV–H), high intensity ultrasound (PV–U), and their combinations (PV-pH-H, PV-pH-U, PV-H-U) on the structural, foaming, and surface behavior at the air-water interface of the modified pea vicilin (PV) protein fraction were comprehensively evaluated. Results showed that the foaming capacity (FC) of samples treated by either PV-pH or PV-H was significantly increased (105.26%, 105.64%) as compared to the control (73.53%). This synergistic effect was observed with the combination of pH-shift and controlled heating (PV-pH-H), which drastically improved the FC of the modified PV (153.97%). Interestingly, ultrasound treatment exhibited the least effect on the FC of PV, no matter whether it was applied individually or combined with other treatments. The improved FC of PV was mainly attributed to newly formed soluble aggregates, the transition of β-sheet to α-helix, and increased surface hydrophobicity (H0), allowing PV to exist in a more flexible structure. The dynamic adsorption behaviors of the modified PV at the air-water interface indicated that its improvement in FC was also associated with the high surface pressure with short lag time. In addition, the modified PVs formed a strong elastic interfacial film through densely packed protein molecule as evidenced by E-π slop (>1). This study demonstrated that a simple pH shift combined with controlled heating technique could be applied to improve the foaming properties of PV.