A novel microemulsion loaded with Ligustrum robustum (Rxob.) Blume polyphenols: Preparation, characterization, and application

The low solubility of phenolic compounds in oils limits their protective effect on oil quality. In the present study, novel microemulsions were designed and prepared with Ligustrum robustum (Rxob.) Blume polyphenols extract (LRE) using soybean oil as the oil phase, a combination of Tween80 and Span80 as surfactants, and ethanol as the co-surfactant, and subsequently characterized and evaluated their properties and performance in oil. Results showed that the amount of LRE dissolved in prepared microemulsions could reach 0.025 g/g oil. According to the droplet size, rheology, differential scanning calorimetry, and transmission electron microscopy measurements, LRE had no negative effects on microemulsion structure and increased the particle size, viscosity, and interfacial strength of microemulsion. Moreover, LRE exhibited remarkable antioxidant activities, and the LRE-loaded microemulsions showed no obvious cytotoxicity on Caco-2 cells. Furthermore, the LRE-loaded microemulsions exhibited superior effectiveness in inhibiting oil oxidation during storage, compared to the direct addition of LRE. All results suggest that the microemulsion has the potential used as an embedded material for natural antioxidants in food industry.