Comparative analysis of high-intensity non-thermal physical treatments on the structural and functional properties of Spirulina platensis protein

Spirulina platensis protein (SPP) has attracted attention as a sustainable alternative to conventional proteins. However, its structural and functional performance under different processing conditions remains underexplored. This study investigated the effects of three non-thermal physical treatments—high hydrostatic pressure (HHP, 100–600 MPa), high-intensity ultrasound (HIU, 70–100 % amplitude), and high-speed shear homogenization (HSS, 1.0–2.5 W)—on the structure and functionality of SPP. SDS-PAGE revealed treatment-specific alterations in protein subunits, accompanied by distinct changes in sulfhydryl/disulfide, surface hydrophobicity, intrinsic fluorescence, and secondary structure. HIU induced the strongest structural disruption, characterized by reduced α-helix content, exposure of hydrophobic residues, and a pronounced decrease in particle size and ζ-potential, whereas HHP promoted unfolding at moderate pressures but aggregation at higher levels. HSS primarily reduced particle size with moderate effects on unfolding. Collectively, these results indicate that high-Intensity non-Thermal physical treatments effectively modulate the functional properties of SPP, demonstrating its potential as a protein ingredient for food applications.