Caffeoylquinic acid-mediated modification of a soybean β-conglycinin fraction under alkaline conditions: structural and functional properties.

This study compared the structural and functional properties of a soybean 7S-enriched β-conglycinin fraction treated with chlorogenic acid (CA) or isochlorogenic acid C (IAC) under alkaline conditions. CA exhibited higher apparent binding efficiency than IAC, with maxima of 93.48 ± 1.23% and 62.95 ± 0.76%, respectively. Compared with CA-treated samples, IAC-treated samples showed greater increases in α-helix content and decreases in β-sheet content, generally smaller particles, more negative ζ-potentials, and higher emulsifying indices, radical-scavenging activities, and thermal transition temperatures. At a protein-to-polyphenol mass ratio of 5:1, solubility reached 76.45 ± 9.37% with IAC and 67.32 ± 7.84% with CA, while DPPH radical-scavenging activity reached 76.42 ± 8.63% with IAC. Higher apparent binding efficiency did not consistently correspond to better functional performance. These findings inform polyphenol selection for improving ingredient functionality in soy protein processing.