Abstract: Sustained-release microcapsules were prepared by spray-drying using β-cyclodextrin (β-CD), β-CD + maltodextrin (MD), octenylsuccinate starch sodium (OSS) or casein (CS) as wall material and vanilla essential oil as core material. A comparative evaluation of four wall materials was made based on microcapsule yield, encapsulation efficiency, solubility, releasing rate, and emulsion stability. The results showed that vanilla essential oil microcapsules with OSS as wall material (VO-OSS) had the highest yield (84.17%) with an encapsulation efficiency of 78.04%, and the reconstitution properties, solubility (96.31%) and emulsion stability (97.82%) were good. vanilla essential oil microcapsules with β-CD + MD as wall material (VO-MD) showed the lowest yield (71.37%) and encapsulation efficiency (61.18%). VO-OSS showed the smallest particle size of 190 nm. Scanning electron microscopic (SEM) observation showed that VO-OSS had a smooth spherical appearance. After 10 days of storage at 60 ℃, VO-OSS remained 54.62% vanillin, which indicated that the sustained-release property of VO-OSS was higher than three other kinds of microcapsules. In conclusion, OSS is the best wall material for vanilla oil microcapsules based on all indicators.

Key words: wall materials, vanilla essential oil, microcapsules, characteristics