Influence of hemin on structure and emulsifying properties of soybean protein isolate

Hemin has potential application value in plant-based meat analogues. However, mechanisms of interaction between hemin and plant protein are unclear. In this study, soy protein isolate (SPI) was applied to examine these interactions using multi-spectroscopic and molecular docking techniques. Additionally, the influence of hemin on emulsification of SPI was also explored. Fluorescence and UV–Vis spectra showed quenching of SPI by hemin was static, resulting in conformation changes on the surface amino acid residues, around which hydrophobicity was significantly reduced from 425.9 ± 16.2 to 108.9 ± 1.8 (p < 0.05). FTIR and CD spectra results suggested the protein secondary structure altered, and the content of α-helix and random coils increased by 1.13% and 1.43%, respectively. Furthermore, emulsifying properties of SPI were strengthened with increased hemin. This work improves our understanding of interactions between SPI and hemin and offer a theoretical basis for application of heme in plant-based meat analogues.