Interactions mechanisms decoding of macadamia protein isolate-procyanidins dimer complexes and synergistic effect for high internal phase Pickering emulsions stabilization.

Macadamia protein isolate (MPI) is a promising plant-based protein but its poor emulsifying functionality limits broader applications. This study investigated the interaction mechanisms between MPI and procyanidin dimer (PA2) and their synergistic effect on the stabilization of high internal phase Pickering emulsions (HIPPEs). Spectroscopic and physicochemical analyses demonstrated that MPI and PA2 formed complexes through a spontaneous binding process mainly driven by hydrogen bonding, accompanied by hydrophobic interactions. These interactions induced notable conformational changes in MPI, leading to a reduced particle size, enhanced surface charge, and modified hydrophobicity. Moreover, MPI-PA2 complexes significantly enhanced interfacial activity by efficiently adsorbing at the oil-water interface. Consequently, HIPPEs stabilized by the complexes exhibited smaller droplet sizes, improved physical stability, and superior viscoelastic properties. Overall, this work highlights the potential of MPI-PA2 complexes as a promising bio-based emulsifier and functional delivery system, providing new insights into the value-added utilization of plant proteins in food applications.