Oil powders stabilized with soy protein used to prepare oil-in-fat dispersions

Abstract

We report on the use of a soy protein stabilized, spray-dried oil powder as a vehicle for the introduction of unsaturated liquid oil in a continuous fat matrix. The spray dried oil powder was mixed with the molten continuous fat phase in concentrations of 30, 40, 50 and 60% of powder. The static crystallization of the continuous fat phase resulted in the formation of oil-in-fat dispersions, as was visualized with light microscopy and cryo-SEM. The isolation of the liquid oil in the internal oil droplets ensured that the continuous fat phase dominated the structuring of these newly developed oil-in-fat dispersions, which was rheologically demonstrated with amplitude sweeps. The elastic modulus of a 40% oil-in-fat dispersion (G’LVR = 3.54 ± 0.731 *105 Pa) was not significantly different from that of the undiluted fat phase (G’LVR = 4.55 ± 1.87 *105 Pa), even though the dispersion contained 40% more unsaturated oil. However, thixotropic tests revealed that the oil-in-fat dispersions are shear sensitive which can limit their applicability. The recovery percentage after shear of the undiluted fat was 39%, while the 30 and 40% oil-in-fat dispersion had a maximal recovery percentage of 19%.These findings provide a potential approach to reduce the saturated fat content of fat-based food products using only food-grade ingredients and traditional food processing techniques. Nevertheless, further optimization of the emulsion formulation and preparation and of the spray drying process is essential to improve the shear stability of these oil-in-fat dispersions.