Optimization in High-pressure Microfluidics Preparation of Black Pepper Essential Oil Nanoemulsion by Response Surface Methodology and Its Component Analysis

In order to improve the irritating odor and stability problems existing in the application of black pepper essential oil (BPEO) in food preservation, BPEO was used as oil phase and Tween 80 was used as emulsifier. The single factor test and Box-Behnken response surface method were utilized to optimize the process parameters of nanoemulsions prepared by high-pressure microjet homogenization technology. The composition of BPEO nanoemulsions was analyzed by infrared spectrometry and gas chromatography-mass spectrometry (GC-MS). The results demonstrated that the ideal process parameters were the homogenization pressure of 175 MPa, homogenization cycles were 2, and Tween 80 concentration of 1.5%. The particle size of BPEO nanoemulsion prepared under these conditions was 126.64 nm and the polymer dispersity index (PDI) was 0.238. Most of the functional groups of Tween 80 and BPEO exist in the BPEO nanoemulsion, and the wavenumber changes of the characteristic absorption peaks were slightly small, which proved that BPEO was successfully wrapped in the droplet. The composition of BPEO nanoemulsion mainly contained caryophyllene (29.32%), D-limonene (14.05%), β-pinene (13.17%), bicyclo[3.1.0]hexane,4-methylene-1-(1-methylethyl) (8.69%), copaene (2.89%), caryophyllene oxide (1.61%), linalool (0.27%), terpinen-4-ol (0.62%) and γ-terpinene (0.21%). Most of the active ingredients were detected in BPEO. The results indicated that the high pressure microjet homogenization technology did not destroy the bioactive ingredients of BPEO, the prepared BPEO nanoemulsion was expected to maintain the same bioactivity and good stability as BPEO, and could be used for food preservation.