Properties of milk protein concentrate stabilized oil-in-water emulsions

Oil-in-water emulsions (30% rapeseed oil) stabilized with milk protein concentrate were obtained at the temperature of 60 °C and pressure 10 and 2 MPa. The emulsion phases were preheated prior to homogenization at 60, 70, 80, 90 or 95 °C for 5 min in order to evaluate the effect of phase preheating and preheating temperature on stability, particle size distributions and flow behavior of examined emulsions. The protein particle sizes, viscosity, emulsifying capacity of the continuous phase and rheology of dispersed phase were also analyzed. Emulsion particle size measurements gave bimodal distributions. Emulsions formed from unheated proteins were less stable (42.4%) and an increase in preheating temperature increased emulsion stability up to 50.4%. Preheated oil gave more stable emulsions; however, the emulsion stability decreased from 52.2% to 48.2% with increase in oil heating temperature. Preheating of the continuous and dispersed phase influenced flow properties of the emulsions (p < 0.05).