Abstract
The study examined how transglutaminase (TG)-induced cross-linking affects the structural, functional, and in vitro digestibility characteristics of rice dreg protein (RDP). Analysis using SDS-PAGE showed that low-molecular-weight fragments vanished, while high-molecular-weight polymers formed. Additionally, Fourier transform infrared (FTIR) spectroscopy demonstrated a reduction in β-sheet content alongside an elevation in β-turn structures as the cross-linking process became more pronounced, which was associated with a reduction in both total and free sulfhydryl groups. The hydrophobic nature of the surface and the emulsifying properties of cross-linked RDP initially rose but began to decrease when TG concentrations surpassed 10 U/g of protein. Conversely, emulsion stability and water-binding capacity decreased, while oil-binding capacity improved compared to native RDP. Solubility and in vitro digestibility decreased with cross-linking, whereas rheological properties significantly improved with higher TG levels. These findings suggest that controlled TG-mediated cross-linking (e.g., 10 U/g) effectively enhances the functional properties of RDP, making it a promising ingredient for applications in plant-based meats, baked goods, and fortified beverages within the food industry.