Formation of nanoemulsion from black pepper essential oil by high speed homogenization method

Abstract

As many spices essential oil, black pepper (Piper nigrum) oil, which produced by steam distillation has shown the antimicrobial activity in many researches. However, essential oil was often hydrophobic and dispersed incompletely in food matrix. In our work, an oil-in-water nanoemulsion of black pepper oil was prepared by high speed homogenization method. In order to well disperse essential oil in water, the surfactant polyoxyethylene sorbitan monooleate (Tween 80) was utilized with the surfactant:oil ratios from 1:3 to 2:1. The other component of the nanoemulsion was soya oil, the bigh chain triglycerides in soya oil prevented the Oswald ripening of essential oil droplets by increasing their hydrophobicity. After changing the component concentration, the nanoemulsion was the most stable with 20 % oil phase, 6:4 pepper oil - soya oil ratio and 1:1 surfactant oil ratio. At 9,000 rpm and 30 minutes stirring, the average droplet size was 61.9 nm with 0.462 Pdl (polydispersity index). After 30-day storage, the particle size increased to 87 nm at ambient temperature and 130 nm at 5°C.