Improving the solubilization, stability, dialysis performance and antioxidant properties of quercetin in surfactant-free microemulsion

Abstract

The flavonol compound quercetin with poor water solubility, was solubilized in a novel green solvent constructed in this work. The solvent is composed of tributyl citrate, ethanol and water, recognized as surfactant-free microemulsion (SFME). The solubilization behavior and mechanism of quercetin were investigated, the light, thermal, storage stability and antioxidant properties were examined, as well as the dialysis properties and release kinetics. The results reveal that there are interactions existing between quercetin and tributyl citrate. Ethanol and tributyl citrate in SFME also have a synergistic solubilization effect on quercetin. Therefore, the content of quercetin increases with tributyl citrate, and the solubility of quercetin in oil in water SFME (RE/W = 7:3, ƒO = 0.1) is 9.88 mg/ml, much higher than that in water or ethanol. The light, heat, storage stability and antioxidant properties of quercetin are greatly improved by SFME. In the dialysis process, the release of quercetin in SFME follows a non-Fickian diffusion mechanism with a slow-release action. The SFME established has green and non-toxic advantages in the application of the solubilization field, and it is expected to provide important guidance for the extraction and separation of natural foods.