Submicron emulsions processed by ultra-high pressure homogenization

Abstract

Model oil/water (O/W) emulsions containing (w/w) 15–45% peanut oil plus 4.3% whey proteins or raw whole milk (∼4%, w/w, fat) were processed by ultra-high pressure (HP) homogenization at an inlet temperature of 24 °C using an HP homogenizer with an HP valve, immediately followed by cooling heat exchangers. Mechanical and thermal energies involved in the process were calculated using pressure and temperature values measured at the HP valve inlet and immediate outlet. For all samples, an increase in homogenization pressure decreased the droplet size, leading to submicron fat particles at pressure≥200 MPa and monomodal distributions in the nano-scale range by emulsion recycling once or twice at 200 MPa. Further, microbial inactivation in raw whole milk was enhanced by increasing the homogenization pressure or by recycling milk at 200 MPa. Rheological behavior of model O/W emulsions varied as a function of oil droplet size and oil volume fraction.