Multispectral and molecular dynamics investigation of GABA-induced gelation behavior in walnut protein isolate.

Walnut protein isolate (WPI) is a high-quality plant protein source. However, its application in gel-based foods is limited by weak gelling properties. The present study elucidated the molecular mechanisms by which γ-aminobutyric acid (GABA) enhanced the gelation of WPI. The addition of GABA (0.80%) significantly increased the water holding capacity of WPI gels (from 61.9% to 85.2%) and improved the textural properties, including hardness and springiness. Mechanistically, GABA induced protein unfolding (transitioning α-helix to ordered β-sheets), exposing buried hydrophobic groups. This facilitated a dense, fine-stranded network stabilized by enhanced hydrogen bonding and hydrophobic interactions. Molecular dynamics simulations revealed that GABA triggered global structural rearrangement in walnut glutelin, while inducing local conformational activation in 11S globulin. Notably, the GABA-glutelin complex maintained high stability via hydrogen bonds and van der Waals forces, serving as the primary driver for enhanced mechanical strength. This study clarified how GABA regulated the gelation behavior of WPI through protein conformational rearrangement and enhanced intermolecular interactions, providing a theoretical basis for improving the application of walnut protein in structured plant-based foods.