Structural Transformation and Functional Improvement of Potato Protein–Gallic Acid Conjugates: Multispectroscopy and Molecular Dynamics Simulations

Covalent modification of polyphenols effectively enhances functional properties of proteins. This study conjugated potato protein isolate (PPI) with gallic acid (GA) via an alkaline method to investigate structural and functional alterations. Successful conjugation was confirmed by a significant decrease in free amino and sulfhydryl groups, coupled with a marked increase in total phenolic content. Multispectroscopic analyses indicated a loosening of the secondary structure and notable changes in the tertiary conformation. Molecular dynamics (MD) simulations corroborated these findings, revealing that GA conjugation induced conformational expansion, improved structural stability, and enhanced surface hydrophilicity. These structural modifications led to substantial functional improvements in the PPI-GA conjugates, including enhanced dispersion stability, improved emulsifying performance, strengthened antioxidant activity, and increased thermal stability. This research may provide effective strategy and technical support for the improvement of functional properties of PPI and expand its application in the food industry.