Molecular Transformation and Characterizations of Super-deamidated Wheat Gluten by a Tunable Hydrated Ternary Natural Deep Eutectic Solvent

The utilization of natural deep eutectic solvents (NADESs) for super-deamidation of wheat gluten represents a cost-effective approach to expand its potential applications as a plant protein source and reduce the occurrence of allergens. However, NADESs are susceptible to deconstruction during hydration, leading to unstable super-deamidation. Herein, we prepared a ternary hydrated NADES (HB3C1G1-N) composed of betaine, citric acid, and glucose, doubling the protein preparation concentration (50 mg/mL) compared to previous work and achieving a record-breaking degree of super-deamidation at 99.58%. Experimental and computational analyses revealed that the betaine in the NADES autonomously interacts with the citric acid and glucose at the hydrogen bond acceptor sites during hydration, reversing the disassembly of the hydrogen bond network in water and playing a crucial role in the accessibility of the buried amide group. The super-deamidated wheat gluten exhibited structural characteristics, such as fewer disulfide bonds and more low-molecular-weight subunits, resulting in a lightning-like microstructure in the model emulsion and improving the stability of oil droplets. This work demonstrates a green and scalable super-deamidation pathway and provides a foundation for broadening the application of super-deamidated wheat gluten.