Influence of protein source on the morphology, physicochemical and flow properties of protein-based emulsion particles to be used as texture modulators

The present study compared the influence of heating (95 °C for 90 s) formulations based on globular proteins with similar isoelectric points (whey, pea, potato and soy), with the same nutrient composition (3 wt% protein; pH 6.6; 0–0.95 wt% NaCl; 0–0.10 wt% CaCl2; 0–5 wt% high oleic sunflower oil) and processed using the same conditions (homogenization and shearing post heat treatment), on the morphology, physicochemical and flow properties of the resulting aggregated systems. Some trends in the aggregation behavior among the different protein-based formulations were identified, but the extent of the modifications promoted by heat treatment was protein source-dependent. Heat treatment of the oil-free formulations in the presence of added salts resulted in extensive protein aggregation, as inferred from the considerable decrease in protein solubility and increase in particle size. Interestingly, addition of oil to the various salts-containing formulations led to a further increase in the aggregation yield and a decrease in particle size. The morphology of the aggregates differed considerably depending on the protein source used, with oil addition leading to a loss of protein network. Furthermore, addition of oil to plant protein-based formulations promoted a marked increase in viscosity upon heat treatment, whereas the opposite phenomenon was observed for whey protein-based formulations. The differences observed among the various protein-based aggregated systems in terms of morphology, physicochemical and flow properties may be ascribed to differences in their sensitivity towards added salts and emulsifying ability, as observed before heat treatment, as well as in their denaturation temperature, given the relatively short heating time used in this study. Therefore, formulation and processing need to be adapted to the protein used if aggregated systems with similar properties want to be obtained starting from different protein sources under intermediate degrees of electrostatic repulsion.