Ultrasound-mediated nettle oil nanoemulsions stabilized by purified jujube polysaccharide: Process optimization, microbial evaluation and physicochemical storage stability

Abstract

Optimizing the manufacturing conditions of stable oil-in-water submicron emulsions using ultrasound assisted emulsification is a critical challenge in food and bio-industries. The influence of irradiation time (IT, 5–25min) and ultrasonic applied power (UAP, 50–250W) was studied on formation of stinging nettle essential oil (1.25wt%)-nanoemulsions (SNEO-NEs) in aqueous solution of purified jujube polysaccharide (JCP-1, 1.5wt%). Use of the single-factor and response surface methodologies showed an UAP of 165.87W and an IT of 23.64min can result in the best NE physicochemical properties including 86.75 nm droplet size, 0.079 polydispersity index, 1.331 refractive index, 34.5mN/m surface tension, 4.49mPa·s viscosity, 0.958meqO2/kg oil peroxide value and 0.814 anisidine value. Kinetic analysis of stability and antioxidant losses of the optimal SNEO-NEs stored for 45 days demonstrated although there was no substantial difference in the droplets growth between 4 and 25°C, a lower oxidative stability rate (24.1%) was monitored at 4°C. The Gram-positive bacterium also was more inactivated by the optimal NE compared with the Gram-negative one (P<0.05). This novel NE-based delivery system can be a successful strategy for the controlled release of other poorly water-soluble components with the improved functionalities.