Nano-emulsion prepared by high pressure homogenization method as a good carrier for Sichuan pepper essential oil: Preparation, stability, and bioactivity

Abstract To surmount the defects of Sichuan pepper essential oil (SPEO) including poor stability and low water solubility and expand it application in water-based foods. SPEO nano-emulsion (SPEO-NE) was prepared by high pressure homogenization with Tween-80 (T-80) and caprylic/capric triglyceride (ODO) as emulsifiers. By response surface design, the optimal preparation conditions of SPEO-NE were determined as follows: mass fraction of SPEO was 3.00%, ODO: T-80 = 7:3, mass fraction of emulsifier was 2.50% and the number of homogenizations was three. The results showed that the optimized SPEO-NE had long-term storage stability. After 31 days of storage at 4 °C and 25 °C, the average particle size and zeta potential just changed from 125.07 nm and −33.12 mV to 134.53 nm and −29.27 mV, respectively. In addition, nano-emulsification improved the inhibitory effect of SPEO on E. coli and S. aureus while its antioxidant activity was not weakened. The results of microstructure, heating and TGA analysis showed that the thermal stability of the essential oil was significantly improved after emulsification.