The Effect of Heat- and Salt Treatment on the Stability and Rheological Properties of Chickpea Protein-Stabilized Emulsions

The aim of the study was to evaluate the effect of heat- (95 °C) and/or salt (0.1 M NaCl) treatment on the physical stability and rheological properties of oil-in-water emulsions stabilized with chickpea protein concentrates (CPCs) for various purposes. Thus, the particle size distribution (PSD), shear behavior, and long-term Turbiscan stability of the prepared emulsions were examined. The oscillatory (dynamic) measurements were also performed to obtain information on the viscoelasticity of tested fluids during thermal treatment. The obtained results indicated that the emulsion stabilized with gelling CPC (eCg) was Newtonian fluid with a homogeneous structure, but susceptible to creaming. Heat-treated eCg exhibited a sol–gel transition at 86 °C and formed fine-stranded aggregates without affecting stability. In turn, heat-induced gelation of eCg in the presence of 0.1 M NaCl resulted in the formation of an aggregated, spatial gel network, stabilization of the system, and a significant change in both shear rheological properties and PSD. Contrariwise, emulsions stabilized with standard CPC (eCs) were unstable heterogeneous systems containing both fine particles < 1 μm and coarse particles of about 100 μm, exhibiting shear-thinning and yield stress. The heat-induced viscoelasticity of eCs was reversible, while heat- and salt-treated emulsions did not form a gel.