Phosphorylation modification of Trichosanthes kirilowii seed protein isolates: An effective foaming enhancement strategy.

The development and utilization of plant protein resources continue to attract considerable attention. Phosphorylation is an effective technique for improving protein functionality, yet its specific influence on Trichosanthes kirilowii protein isolate (TPI) remains unexplored. In this study, TPI was modified through phosphorylation using sodium tripolyphosphate (STP) and sodium trimetaphosphate (STMP), respectively, and the optimum phosphate grafting was achieved at a concentration of 4%, reaching 21.35 ± 1.08 mg/g for STP and 21.98 ± 1.64 mg/g for STMP. Compared with native TPI, phosphorylated TPI increased the absolute Zeta potential and surface hydrophobicity, while Fourier transform infrared spectrometer and X-ray diffraction analyses revealed a transition toward more flexible and disordered secondary structures. X-ray photoelectron spectroscopy analysis further confirmed the covalent incorporation of phosphate groups via PO and PO bonds. These structural modifications enhanced the foaming properties of TPI, with the foaming ability increasing from 40 ± 9.43% to 253.33 ± 18.86% and foaming stability achieving 60.95 ± 0.48%. When applied as a 25% egg white replacer in angel cake, phosphorylated TPI significantly increased batter viscoelasticity, specific volume, and crumb springiness compared to unmodified TPI, while maintaining sensory acceptability. These findings demonstrate that phosphorylation is an effective strategy to substantially improve the foaming properties of TPI.