Comparison of the physical properties and microstructure of bigels prepared from ethyl cellulose oleogels and konjac glucomannan hydrogels containing casein or whey protein isolate

Bigels were prepared from ethyl cellulose oleogels and binary hydrogels containing konjac glucomannan (KGM) and two homologous proteins: casein (CS) and whey protein isolate (WPI). An increase in CS concentration led to an initial enhancement, followed by a reduction in the yield stress and hardness of the bigels. Conversely, variations in WPI concentration did not have a significant effect on these properties. As protein concentration increased, WPI-based bigels maintained the hydrogel-in-oleogel structure, whereas CS-based bigels exhibited phase inversion. The change in binary hydrogels was responsible for the structural evolution and property differences in bigels. Both CS–KGM and WPI–KGM binary hydrogels played a role in stabilizing the droplets and decreasing interfacial tension. Notably, CS–KGM mixtures demonstrated superior emulsification performance compared to WPI–KGM mixtures. By changing the type and concentrations of proteins used, different emulsification abilities can be achieved in hydrogel solutions, which in turn control the structural properties of the corresponding bigels.