Fabrication of natural W1/O/W2 double emulsions stabilized with gliadin colloid particles and soybean lecithin

In this study, we successfully fabricated W1/O/W2 double emulsions and high internal phase double emulsions with gliadin colloid particles (GCPs) as the hydrophilic emulsifier and soybean lecithin as the hydrophobic emulsifier, which were obtained from natural resources and avoided the use of surfactants such as PGPR. The effects of lecithin concentration, GCP concentration, W1/O volume ratio, and pH of the external aqueous phase on the physical properties and encapsulation efficiency of the double emulsions were investigated. The double emulsions presented an encapsulation efficiency (tartrazine was used as an aqueous marker) up to 91.1 ± 0.2% under the optimised conditions (GCP concentration 2% (w/v), lecithin concentration 1% (w/v), pH 6 of the W2 phase, W1/O volume ratio 1:5). After 30-days of storage at room temperature, the encapsulation efficiency of the double emulsions remained stable at 88.8 ± 0.2%, indicating good encapsulation stability. The double emulsions exhibited pH response characteristics; their appearance changed from a semi-solid to a flow state as the pH of the W2 phase increased, and the formation of the gel net structure facilitated the maintenance of the internal aqueous phase during fabrication and storage. This study provides a strategy for the fabrication of natural double emulsions with satisfactory encapsulation efficiency.