Atmospheric cold plasma pretreatment for effective enhancement of covalent crosslinking between coconut globulin and tannic acid: Improving interfacial activity and emulsifying properties.

Atmospheric cold plasma (ACP) represents a promising approach for enhancing covalent interactions between proteins and polyphenols, circumventing the drawbacks associated with traditional methods. This study aims to investigate the enhancement of covalent interactions between coconut globulin (CG) and tannic acid (TA) facilitated by ACP at varying pH levels. At acidic pH, ACP treatment was found to promote free radical-induced covalent cross-linking between CG and TA, whereas at pH 7.0 and 9.0, ACP treatment enhanced quinone-induced covalent cross-linking. In contrast, the covalent crosslinking induced by quinone significantly disrupted the protein structure, leading to greater exposure of hydrophobic groups. At pH 9.0, the CG-TA complex treated with ACP exhibited the highest interfacial activity, with an interfacial adsorption mass of 5292 ng/cm. This was accompanied by improvements in droplet size, viscosity, and stability of the CG-TA-stabilized emulsion. These findings offer novel insights into the covalent modification of proteins and polyphenols, thereby broadening the potential applications of food protein.