Covalent modulation of zein surface potential by gallic acid to enhance the formation of electrostatic-driven ternary antioxidant complex coacervates with chitosan

Despite existing research on the interaction between zein (Z) and chitosan (CS), the formation and mechanisms of ternary electrostatic coacervates incorporating polyphenols remain unclear. Herein, we covalently and non-covalently modified zein with gallic acid (GA). Comparisons revealed that the covalent coupling of Z with GA (forming Z(GA)) reduced zein's surface potential, enabling them to form tightly bound coacervates with cationic polysaccharide chitosan through electrostatic attraction. Turbidity, ζ-potential, and appearance experiments indicated that the maximum yield of insoluble coacervates was achieved at a Z(GA)/CS mass ratio of 7:1 and pH 6.5. Furthermore, the coacervate properties were evaluated using Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, and microscopic structure analysis. Electrostatic attraction between the -COO − groups of Z(GA) and the -NH 3 + groups of CS triggered complex coacervation, which induced structural modifications and enhanced thermal stability. This study fosters the efficient encapsulation and controlled release of nutraceuticals, enhancing human absorption.