A series of polyurea-urethane microparticles containing xylitol were synthesized by interfacial polymerization from reaction between diphenyl methylene diisocyanate (MDI) and xylitol. This research was conducted to clarify the influence of different parameters on the encapsulation process, i.e. during the emulsion formation step and during the shell formation using contact angle measurement, Fourier-transform infrared spectroscopy, differential scanning calorimetry and thermogravimetric analyses. By carefully analyzing the influencing factors stirring rate and feeding weight ratio of core/shell monomers, the optimum synthetic conditions were found out. The results show that core/shell weight ratio influences not only the shell formation mechanism but also the mean diameter, microcapsule morphology, the encapsulation yield and the xylitol content. Thus, the choice of a core/shell weight ratio of 77.0-23.0 is the most suitable to obtain high encapsulation yield and xylitol loading content. (C) 2010 Published by Elsevier B.V.