Antimicrobial eugenol nanoemulsion prepared by gum arabic and lecithin and evaluation of drying technologies

Abstract

The purpose of present work was to develop eugenol oil nanoemulsions using gum arabic and lecithin as food grade natural emulsifiers, and study their antimicrobial activity. In addition, our study also evaluated different drying techniques (spray drying and freeze drying) on the morphology and redispersibility of nanoemulsion powders. The optimal fabrication method, physicochemical and structural characterization, stability, and antimicrobial activity were investigated. Results showed that nanoemusions with a particle size of 103.6±7.5nm were obtained by mixing aqueous phase (0.5% gum arabic, 0.5% lecithin, w/v) and eugenol oil (1.25%, w/v), which was premixed with ethanol (as a co-surfactant), followed by high speed homogenization process. The molecular interactions among emulsifiers and eugenol were evidenced by Fourier transform infrared spectroscopy. Buchi B-90 Nano Spray Dryer was evaluated as a powerful tool to obtain ultrafine spherical powders with a size of less than 500nm, compared to flake-like aggregation obtained by freeze-drying. The dried powders exhibited excellent re-dispersibility in water and maintained their physicochemical properties after re-hydration. The nanoemulsions did not adversely affect the antimicrobial activity of eugenol against Listeria monocytogenes and Salmonella Enteritidis. Therefore, the nanoemulsions have the potential to be applied in the food industry as a food preservative or sanitizer.