Accelerated stability testing of a water-in-oil emulsion

Non-optimal or non-predictable stability properties of emulsions can be limiting for the applications of emulsions. Therefore, it is of general interest to predict stability behavior. In the present study, accelerated stability testing employing elevated temperatures with good accuracy predicted long-term stability of a w/o emulsion stabilized with polyglycerol polyricinoleate (PG PR) kept at 4 degreesC It is argued that elevated temperature testing may successfully be applied to w/o emulsions provided that the phase inversion temperature is not crossed during the accelerated study. Furthermore, some qualitative effects of temperature on chemical stability could be observed. It was found that triglycerol polyricinoleate-6 provided the highest physical stability of four qualities of PG PR. Release characteristics of two entrapped hydrophilic markers, glucose and polyethylene glycol (m.w.4000) showed different sensitivities towards thermal stressing. The high releasing compound, glucose, showed a significant reduction in release rate in contrast to polyethylene glycol.