Effects of partial hydrolysis and subsequent cross-linking on wheat gluten physicochemical properties and structure

• An appropriate hydrolysis allowed the compact wheat gluten structure to unfold.
• The unfold structure facilitates MTGase cross-linking.
• Composite modification could improve wheat gluten rheological behavior and thermal properties.
• Excessive hydrolysis resulted in HMW-GS degrading to smaller peptides.

The rheological behavior and thermal properties of wheat gluten following partial hydrolysis using Alcalase and subsequent microbial transglutaminase (MTGase) cross-linking were investigated. The wheat gluten storage modulus (G′) and thermal denaturation temperature (Tg) were significantly increased from 2.26 kPa and 54.43 °C to 7.76 kPa and 57.69 °C, respectively, by the combined action of partial hydrolysis (DH 0.187%) and cross-linking. The free SH content, surface hydrophobicity, and secondary structure analysis suggested that an appropriate degree of Alcalase-based hydrolysis allowed the compact wheat gluten structure to unfold, increasing the β-sheet content and surface hydrophobicity. This improved its molecular flexibility and exposed additional glutamine sites for MTGase cross-linking. SEM images showed that a compact 3D network formed, while SDS–PAGE profiles revealed that excessive hydrolysis resulted in high-molecular-weight subunits degrading to smaller peptides, unsuitable for cross-linking. It was also demonstrated that the combination of Alcalase-based partial hydrolysis with MTGase cross-linking might be an effective method for modifying wheat gluten rheological behavior and thermal properties.