Encapsulation of D-limonene in Alyssum homolocarpum seed gum nanocapsules by emulsion electrospraying: Morphology characterization and stability assessment

Abstract

The main purpose of this research was nanoencapsulation of D-limonene with Alyssum homolocarpum seed gum (AHSG) using electrospraying process. For this purpose it was necessary to identify and optimize the factors affecting the morphology of electrosprayed nanocapsules. To this aim, D-limonene emulsions with various concentrations of AHSG and Tween 20 were homogenized by ultrasound or high speed homogenizer and electrosprayed under different process conditions including applied voltage and solution flow rate. Results indicated that the physical properties of emulsions, including viscosity, surface tension and electrical conductivity were greatly influenced by the concentrations of their ingredients, and also by the homogenization method. The physical properties of emulsion along with the processing parameters (voltage and flow rate) were the key factors affecting the morphology and size of the obtained structures (p<0.05). Briefly, round, smooth and compact capsules with an average diameter of 65.68 ± 8.80 nm were obtained from electrospraying of high speed homogenized emulsion containing 0.5% gum (w/w), 20% D-limonene (w/w) and 0.1% surfactant (w/w) under the applied voltage of 20 kV and flow rate of 0.1 mL/h. These optimum nanocapsules showed 73.4% encapsulation efficiency. The stability of encapsulated D-limonene was also monitored for 90 days at 4 °C and 25 °C. Nanocapsules provided a relatively good storage stability and maintained 91.2% and 82.4% of initial mass of the loaded D-limonene during 90 days of storage at 4 °C and 25 °C, respectively.