Physical and rheological properties of agglomerated milk protein isolate–guar gum mixtures: effect of binder type and concentration

Our study sought to investigate how the fluidized-bed agglomeration process, incorporating sugar and sugar alcohol binders, affects the physical and rheological properties of milk protein isolate (MPI)–guar gum (GG) mixtures. The agglomerated MPI-GG mixtures (AMGs) consisted of larger and more porous particles with a uniform particle size distribution and showed better solubility compared to non-agglomerated MG (NMG). Additionally, the agglomeration process with binders improved powder flowability by reducing powder cohesion. However, AMGs exhibited lower apparent viscosity and viscoelastic moduli than NMG, and these values decreased with higher binder concentrations because the presence of sugar and sugar alcohol binders promoted the depletion interaction between MPI and GG. This finding was supported by confocal laser scanning microscopic images, which showed more and larger GG lumps in AMGs than in NMG. Our findings may contribute to the utilization of AMGs in various foods including dairy products.