Development and evaluation of delivery systems for quercetin: A comparative study between coarse emulsion, nano-emulsion, high internal phase emulsion, and emulsion gel

This study aimed to identify the most suitable delivery system for quercetin. To achieve this objective, four delivery systems, i.e., coarse emulsions, nano-emulsions, high internal phase emulsions (HIPEs), and emulsion gels, were prepared and characterized by structure, rheology, stability, and bioaccessibility. The nano-emulsion exhibited the smallest particle size, highest absolute ζ-potential, and best thermal stability and storage stability. The HIPEs showed the best freeze-thaw and oxidative stability. Regarding rheology, all delivery systems exhibited elastic gel-like behavior, which consistent to the characteristics of non-Newtonian fluids. The encapsulation efficiencies of quercetin in these delivery systems were greater than 81.56%. The lowest rate of free fatty acid release was observed in the HIPEs, and the highest bioaccessibilities of quercetin were observed in the nano-emulsion and emulsion gel. Thus, the nano-emulsion is the most suitable for the delivery of quercetin among the four delivery systems.