After the oil and water phases had been separately prepared, the water phase was continuously added to the oil phase at room temperature with slightly mixing. A transparent yellow microemulsion was obtained. the colour characteristic of the microemulsion was expressed as values of 32, 15 and 41 for L* (luminosity), a* (intensity of red) and b* (intensity of yellow) values, respectively. The mean hydrodynamic diameter of the internal phase was 45 ± 7.2 nm as repeatedly