Influence of emulsion properties on the microencapsulation of orange essential oil by spray drying

This work aimed to study the effect of emulsion properties on the microencapsulation of orange essential oil by spray drying. The study was performed using a 2 central composite design, where the independent variables were the total solid content (0-30%), the ratio of oil/total solids (0-30%) and the homogenization pressure used for emulsification (0-1000 bar). Whey protein concentrate and 20 DE maltodextrin, mixed in a 1:3 ratio, were used as wall materials. The emulsions were first prepared by blending the oil and the wall solution, using a rotor-stator blender; they were further emulsified using a high pressure homogenizer. All emulsions were characterized for viscosity and droplets mean diameter. Microencapsulation was performed in a laboratory scale spray dryer and particles were characterized for total and surface oil content. From these results, encapsulation efficiency and oil retention were calculated and analyzed as responses, being used for process optimization. In general, the best process responses were obtained at moderate homogenization pressures (400-650 bar), in which emulsions had the smallest droplet diameters. Higher solid content and lower oil concentration resulted in higher encapsulation efficiency and greater flavor retention, which was attributed to the higher viscosity and smaller droplet size presented by the emulsions produced under these conditions.