Mung bean protein fibrils reinforce whey protein gels at neutral pH: Effects of fibril maturity, concentration, and microstructure

The effect of mung bean protein fibrils (MF) as active nanoscale scaffolds on the heat-induced gelation of whey protein isolate (WPI) at pH 7 was studied. The microstructural features, intermolecular interactions, and rheological properties of WPI-MF composite hydrogels formulated with MF induced from different heating times (4 h, 8 h, and 12 h) and protein concentrations (0.1 wt%, 0.3 wt%, and 0.5 wt%) were investigated compared to pure WPI gels (Control). After heating at 90 °C for 30 min, WPI formed weak amorphous particulate networks, and the incorporation of β-sheet-rich MF significantly co-assembled into highly interconnected networks as revealed by X-ray diffraction (XRD), scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). The CLSM images of gelled samples were analysed by a novel ResNet-34 transfer learning framework coupled with principal component analysis (PCA) to obtain the microstructural differences, indicating that 0.3 wt% MF as the critical concentration for structural reinforcement. The WPI-MF composite gels demonstrated significant rheological reinforcement, leading to an exceptional growth in the storage modulus ( G' ). This might be because MF efficiently recruited WPI molecules, resulting in the non-network protein fraction dramatical decrease of more than 30%. Furthermore, the solvent-extraction results suggest that hydrophobic associations made the largest operational contribution to maintaining the WPI–MF gel network. This finding demonstrates that utilising plant-derived fibrils as active scaffolds is an effective strategy for fabricating plant-dairy hybrid gels, reducing the overall concentration of WPI usage with excellent viscoelastic properties.