Nano-encapsulation of thyme essential oil in chitosan-Arabic gum system: evaluation of its antioxidant and antimicrobial properties

Abstract

In this study Nano–capsules based on chitosan (CS) and Arabic Gum (GA) with Thyme essential oil (TEO) as an active ingredient were prepared using emulsion method. The nano–capsules were characterized by their Encapsulation efficiency (EE), morphologies, Particle size distributions, Zeta potential and Release (RE). Results showed that nano–capsules produced by using relative ratio CS: GA (1.5%:8.5%) clearly showed the highest Encapsulation efficiency (77.67%) and Zeta potential value (+ 43.17 mV). In vitro release studies demonstrated a prolonged release for the samples with larger CS ratio. Most nano–capsules sizes ranged from 385.2 to 756.1 nm. Scanning electron microscopy (SEM) images showed nano–capsules had a rough surface without the spherical shape for all samples. Quantitative values of antioxidant activity of Thyme essential oil and nano–encapsulated essential oil were studied. The essential oils were investigated for their antibacterial activity against common Gram–positive and Gram–negative pathogenic microorganisms (Staphylococcus aureus and Escherichia coli) by Disk diffusion and dilution method (MIC). Our results reported the better antioxidant and antibacterial effects of the encapsulated TEO in comparison with free TEO. Finally, the mixture of CS: GA at (1.5%:8.5%) can be suggested as suitable wall material for Thyme essential oil encapsulation.