Dementholized peppermint oil (DPO) was successfully encapsulated by polyurea shell which was synthesized through interfacial polymerization of isophorone diisocyanate as monomer with water using N

N

N'

N'-tetramethylethylenediamine as catalyst.Morphology

particle size distribution

reaction degree of the monomer and thermal stability of DPO microcapsules were characterized by scanning electron microscope (SEM)

laser particle size analyzis

Fourier transform infrared spectroscopy

and thermal gravity analysis.The encapsulation efficiency of DPO microcapsules was determined by ultraviolet (UV) spectrophotometer.In addition

the effect of the homogenization rate on average particle size was analyzed

and the morphologies of DPO microcapsules prepared with different kinds of emulsifiers and with different ratios of core/shell materials were also explored respectively.The results showed that the average particle size decreased with the increase of homogenization rate and tended to be stable as it decreased to 1 m.SEM images showed that the optimal morphology of microcapsules is neat sphere by using polyvinyl alcohol as emulsifier with 4:1 ratio of core/shell materials.The UV measurement results showed that the encapsulation efficiency of the core materials can reach up to 84.09 wt%.And the powder microcapsules prepared by freeze-drying contain 72.64 wt% of dementholized peppermint oil.Encapsulated DPO inside the microcapsules demonstrated much better thermal stability than pure DPO.