Modulation of sunflower seed protein structure and functionality by chlorogenic acid interaction and stepwise dephenolization.

Sunflower seed protein is a high-quality plant protein, but chlorogenic acid (CGA) in sunflower meal causes browning and off-flavors, limiting its food applications. This study systematically investigated the interaction mechanisms between CGA and sunflower seed protein and their effects on the protein's structural integrity, functional properties, nutritional attributes, and sensory profile. Twice dephenolization removed >92% CGA. Moderate dephenolization increased β-sheet content and intrinsic fluorescence, enhancing structural compactness. Excessive CGA binding impaired gelling and foaming, while moderate removal improved emulsion stability (∼80%) and maintained oil-holding capacity (2.20 g/g). CGA preferentially bound Arg, Glu, Phe, His, and Lys, causing discoloration; following oxidation, its interactions with proteins generated odor-active aldehydes and ketones, thereby causing off-flavor formation. In contrast, moderately dephenolized sunflower seed protein produced pleasant fruity notes (e.g., ethyl acetate, methyl 2-methylpropanoate). Overall, moderate CGA removal significantly improved structural integrity, functional performance, and sensory profile of sunflower seed protein, providing a theoretical basis for its broader food applications.