Structural characteristics and emulsifying properties of myofibrillar protein-dextran conjugates induced by ultrasound Maillard reaction

In this study, we investigated the effect of the ultrasound-assisted Maillard reaction on the structural and emulsifying properties of myofibrillar protein (MP) and dextran (DX) conjugates with different molecular weights (40, 70 and 150 kDa). Compared with classical heating, mild and moderate ultrasound-assisted methods (100–200 W) could accelerate the later stage of the Maillard reaction, which increased the degree of graft (DG) and the content of advanced Maillard reaction products (MPRs). Structural analysis revealed conjugates obtained by Maillard reaction induced the loss of ordered secondary structures (α-helix, β-sheets) and red-shift of maximum emission wavelength of intrinsic fluorescence spectrum. The conjugate containing 40 kDa DX exhibited higher extent of Maillard reaction compared to those containing 70 kDa and 150 kDa DX under various treating methods. Moreover, the ultrasound-assisted Maillard reaction could effectively improve the emulsifying behaviors. 100 W ultrasound-induced conjugates grafted by 70 kDa DX produced the smallest emulsion size with optimum storage stability. Confocal laser scanning microscopy and analytical centrifugal analyzer further confirmed MP grafted by 70 kDa DX with the assistance of 100 W ultrasound field could produce the smallest and most homogeneous MP-base emulsion with no flocculation. Our study demonstrated that mild ultrasound treatment resulted in well-controlled Maillard reaction, and the related glycoconjugate grafted with 70 kDa DX showed the greatest improvements in emulsifying ability and stability. These findings provided a theoretical foundation for the development of emulsion-based foods with excellent characteristics.