Preparation of microcapsules containing different contents of different kinds of oils by a segregative coacervation method and their characterization

Abstract

Microencapsulation of different oils was performed using a segregative coacervation method. In order to microencapsulate, 20 % oil-in-water (O/W) emulsions were prepared in a continuous phase consisting of a 1 % mixture of hydroxypropylmethylcellulose (HPMC)/sodium carboxymethylcellulose (NaCMC) mass ratio (0.7/0.3) and various concentrations (0, 0.35 and 1 %) of the anionic surfactant sodium dodecylsulfate (SDS). Various interactions between the components occur in the continuous phase of emulsions, which influence the structure and properties of the adsorption layer around the oil droplets. The formed HPMC/SDS complexes in the presence of NaCMC molecules undergo segregative phase separation and form a coacervate which adsorbs onto the oil droplets, forming the wall of the microcapsules. Sunflower oil, pumpkin seed oil and a mixture of sunflower and linseed oil were used as the core material. Microcapsules in the solid form were obtained by spray drying the emulsions. The stability of the emulsions, the particle size and particle size distribution of the emulsions and suspensions of microcapsules and the oil content of the microcapsules were determined. The influence of the oil kind on the properties of the microcapsules was also investigated. It was found that at 0.35 % SDS, a coacervate layer around the oil droplets forms a stabile, compact microcapsules wall, which prevents oil extraction. The kind of oil influences the properties of the emulsions and microcapsules, which is important in the selection of oils for microencapsulation by this method.