Microencapsulation of flaxseed oil by spray drying: Influence of process conditions and emulsion properties

The objective of this work was to evaluate the influence of inlet air temperature and emulsion composition (total solid content and oil concentration), as well as its associated properties (viscosity and droplet size), on the microencapsulation of flaxseed oil by spray drying, using gum Arabic as wall material. Coarse emulsions were prepared by blending the flaxseed oil and the gum Arabic solution, using a rotor-stator blender. They were then characterized with respect to droplet size and viscosity. Microencapsulation was performed in a laboratory scale spray dryer. Seventeen tests were made, according to a 2 central composite design. Independent variables were: inlet air temperature (138 – 202oC), total solid content (10 – 30%) and oil concentration with respect to total solids (10 – 30%). Encapsulation efficiency and lipid oxidation were analysed as responses. Higher oil concentration and lower solid content led to the formation of larger oil droplets and less viscous emulsions. Encapsulation efficiency was negatively affected by oil concentration and positively influenced by total solid content. Lipid oxidation was higher for the emulsions containing higher oil concentration and lower solid content, which was attributed to the lower encapsulation efficiency obtained at these conditions. Peroxide values also increased when inlet air temperature increased.