release properties of thyme oil from microcapsules
Figure 5 shows the behavior of thyme oil release from microcapsules
prepared with different emulsifiers at various storage
temperatures. Although the release rate of thyme oil from microcapsules
was fast during early 10 d, microcapsules exhibited the
sustained release properties as the day progressed. Release rate of
thyme oil can be influenced by surface morphology of microcapsules.
Hong and Park (1999) previously reported that the smooth
surface of microcapsules could affect the sustained release of a core
material. In Figure 3, the surface of microcapsule using SLS was
smooth and there was no pore on the surface. On the other hand,
when microcapsules were prepared with T80 and P127 as emulsifiers,
the surface was rough and porous. Therefore, the release
of thyme oil from microcapsules with added T80 and P127 were
relatively faster than that of with added SLS