Effects of gelation on the stability, tribological properties and time-delayed release profile of double emulsions

Abstract

Due to the unique multi-chamber structure of the double emulsion (DE), gelation different compartments of double emulsions with different gelling strength offers flexible control over their encapsulation and delivery properties. Herein, the aqueous or oil phase of DE was gelled with alginate or beeswax at different gelling strength, and the effects of gelation on the processing stability, rheological and tribological properties as well as the digestion profile of double emulsions were investigated. Gelation in each phase improved the stability of DE (0,0,0), with the oil or external aqueous phase gelation being more efficient in lifting the encapsulation stability after 14 days’ storage (increased from 67.50 ± 2.47% to 86–90% and 84–90%, respectively). Under processing conditions, the oil phase gelled DE was easily destabilized when subjected to heating treatment, but maintained better stability under freeze-thaw or osmotic pressure treatment compared to the internal and external water phase gelled ones. Gelation also actively regulated the rheological and tribological properties of DE, wherein gelation in internal water phase showed the least impact on the rheological properties, gelation in the external aqueous phase and oil phase exerted more significant influence on the viscosity and the tribological properties of DE, respectively. The external water phase gelled DE manifested the time-delayed digestion profile with only 8.09 ± 0.12% of internal marker release at the end of gastric digestion and the FFA release extent was decreased by 41.66% as compared to the DE (0,0,0). The present study offers a valuable guide for rational design of double emulsions with tailor-made processing stability, oral sensation and digestive characteristics.