Investigating binding mechanism between coconut globulin and tannic acid mediated by atmospheric cold plasma: Protein structure and stability

Abstract

Physical methods present promising avenues for inducing covalent modifications of proteins by polyphenols, circumventing the safety and sustainability issues associated with traditional approaches. This study sought to enhance the physicochemical properties of coconut globulin (CG) by facilitating covalent cross-linking with tannic acid (TA) through atmospheric cold plasma (ACP). The ACP treatment effectively transitioned the interaction between CG and TA from non-covalent to covalent in a voltage-dependent manner at pH 6.0, resulting in structural modifications of CG. The treatment with TA enhanced the spherical structure of CG, with a reduction in particle size from 474 to 384 nm. This size reduction was further amplified by the exposure of charged groups induced by ACP treatment. Consequently, the solubility, surface hydrophobicity, and viscosity of ACP-treated CG-TA increased, leading to an elevated denaturation temperature and enhanced physical stability. These results suggest a viable approach to improving the suboptimal physicochemical properties of plant proteins.