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

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, 5-25 min) and ultrasonic applied power (UAP, 50-250 W) was studied on formation of stinging nettle essential oil (1.25 wt%)-nanoemulsions (SNEO-NEs) in aqueous solution of purified jujube polysaccharide (JCP-1, 1.5 wt%). Use of the single-factor and response surface methodologies showed an UAP of 165.87 W and an IT of 23.64 min can result in the best NE physicochemical properties including 86.75 nm droplet size, 0.079 polydispersity index, 1331 refractive index, 34.5 mN/m surface tension, 4.49 mPa.s viscosity, 0.958 meq O-2/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 degrees C, a lower oxidative stability rate (24.1%) was monitored at 4 degrees 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. (C) 2017 Elsevier B.V. All rights reserved.