Using soybean protein isolate (SPI)-sodium dodecyl sulfate (SDS) as wall materials and hexadecane as oil core material, microcapsules were prepared by complex coacervation. First, appropriate coacervation conditions, such as pH, SPI/SDS mass ratio and wall material concentration were determined. Coacervation efficiency was up to 85% under these experimental conditions. The influences of stirring speed and the ratio of core/wall on preparation of microcapsules were examined. The morphology of microcapsules was characterized using an optical microscope, and the loading of hexadecane and encapsulation rate were determined by gas chromatography. It was found that the loading of hexadecane was about 61% when the SPI/SDS ratio was at 2 with stirring rate at 400 r/min. With increase in the core/wall ratio, microcapsule sizes and hexadecane loading were both increased.

Key words: soybean protein isolate, sodium dodecyl sulfate, complex coacervation, microcapsule