Self-Assembled Pea Protein Isolate Nanoparticles with Various Sizes: Explore the Formation Mechanism

Pea protein isolate nanoparticles (PPINs) were successfully prepared by potassium metabisulfite (K2S2O5). The disulfide bonds were disrupted by K2S2O5, and then the PPINs were formed through self-assembly. The average diameter of PPINs increased from 124.7 to 297.5 nm as the concentration of K2S2O5 was increased from 2 to 8 mM, and the PPINs showed higher zeta-potentials (-32.2 to -35.8 mV) and unimodal distribution. The content of free sulfhydryl groups first increased and then decreased with the fracture and reformation of disulfide bonds. Subsequently, the increase of the beta-sheet, which has considerable hydrophobicity, promoted the formation of PPINs. The formation mechanism of PPINs was explored by dissociation tests: hydrophobic interactions maintained the basic skeleton of PPINs, disulfide bonds stabilized the internal structure, and hydrogen bonds existed on the exterior of the particles. This study provided a simple and economical method to fabricate nanoparticles.