Hypothesis: In contrast to when polyglycerol polyricinoleate (PGPR) is used as lipophilic emulsifier, the used oil phase and phospholipid composition have a strong influence on the characteristics of water-in-oil (w/o) emulsions prepared using lecithin. These parameters are also expected to influence the characteristics of the corresponding water-in-oil-in-water (w/o/w) emulsions. Moreover, a hydrophilic emulsifier is typically added to the external water phase of w/o/w emulsions and is also expected to influence the characteristics of the w/o/w emulsions.
Experiments: Lecithin with a varying phospholipid composition was used to prepare w/o emulsions with medium chain triglyceride (MCT) oil as well as long chain triglyceride (LCT) oil. In case the w/o emulsion was stable, w/o/w emulsions were produced as well. Hereby, the w/o/w emulsions were prepared using different hydrophilic emulsifiers.
Findings: Each of the lecithin samples could be used to produce a stable w/o emulsion in MCT-oil. In contrast, a stable w/o emulsion could only be produced in LCT-oil with phosphatidylcholine depleted lecithin. The storage stability of the w/o/w emulsions was also higher in case MCT-oil was used as compared to LCT-oil. Finally, a remarkable influence of the high-HLB emulsifier on the resulting enclosed water volume fraction in the w/o/w emulsions was observed.
Keywords: Double emulsion; Encapsulation; Inverse emulsion; Lecithin; Multiple emulsion.
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