Preparation of W/O/W Emulsions at Low Emulsifier Concentrations

Abstract

W/O/W emulsions were prepared using low concentrations of emulsifiers in the oily and outer aqueous phases, and the formation of the emulsions were evaluated by the encapsulation efficiency of a fluorescent marker in the inner aqueous phase. W/O/W emulsions were produced even at low emulsifier concentrations, although the standard deviation of the encapsulation efficiency immediately after preparation became larger as the emulsifier concentration decreased. Long-term stability of the emulsions with no emulsifier was unsatisfactory, although emulsions with a lipophilic emulsifier only in the oily phase were stable for 30 days with a decrease in the encapsulation efficiency of less than around 5%. Emulsifier species also significantly affected the formation of W/O/W emulsions.