Amyloid Fibrils of Pea Protein Isolated Induced by Cold Plasma Treatment and Its Stabilization on High Internal Phase Emulsions

The potential of forming pea protein isolate (PPI) amyloid fibrils promoted by cold plasma (CP) treatment (40 kV; 0, 3, 5, and 7 min), heat treatment (85°C for 12 h), and its ability to stabilize high internal phase emulsions (HIPEs) was investigated. Results indicated that rod-like amyloid fibrils of PPI were successfully formed and promoted by CP treatment, with a 12 nm diameter and 132-261 nm average length, as confirmed by Thioflavin T (ThT) fluorescence spectroscopy, SEM, and TEM. The globular structure unfolding, cleavage of the backbone of PPI by CP treatment, release of the building block "β-strands" structure, and assembly of the building blocks into fibrils during the fibrillation process were confirmed by SDS-PAGE, FTIR, fluorescence spectroscopy, and hydrophobic analysis. Compared with native PPI, fibrous PPI exhibited a strong capacity for stabilizing HIPEs, and the ability to stabilize HIPEs was PPI fibrils length dependent. Compared with HIPEs stabilized by long fibrils (CP5PF-8 and CP5PF-12), the HIPEs prepared by short fibrils (CP5PF-2 and CP5PF-4) displayed better thermal stability. Moreover, CP5PF-stabilized HIPEs exhibited excellent ionic and storage stability, while PPI amyloid fibrils with shorter lengths (CP5PF-2 and CP5PF-4) showed superior performance compared with longer fibrils lengths (CP5PF-8 and CP5PF-12).