Effect of Environmental Stress on Physical Properties and Antibacterial Activity of Atlas Cedar (Cedrus atlantica) Oil-in-water Emulsion

Synthetic preservative compounds can prevent pathogenic bacterial growth, but they cause other concerns related to the adverse effect on human health. Essential Oil (EO), which possesses antibacterial activity, have potential replacers for synthetic preservatives. This study was conducted to develop Atlas cedar EO antibacterial activity, physical properties and sustainability against environmental stress via emulsification. Firstly, screening to select the most potent EO among various EOs (i.e. anise, Atlas cedar, curry leaf and onion) was done. As Atlas cedar was the most efficient antibacterial agent, emulsions containing Atlas Cedar EO were subsequently prepared using different concentrations of Polysorbate20 via a solvent-displacement technique. The physical properties (droplets size, stability, lightness and turbidity) and antibacterial activity (agar disk diffusion) of emulsions were determined. Results showed that emulsion containing 7% (wt) of Polysorbate20 was the most desirable sample in terms of physical properties of antibacterial activity. Henceforth, it was selected for environmental stresses study (i.e. thermal processing, freeze-thaw cycle and ultraviolet exposure). Results revealed that all types of environmental stresses had a significant (p<0.05) effects on physical properties. Environmental stress treatments showed antibacterial activity enhancement against Gram-positive bacteria. Thus, the present work proved the potential use of emulsion as the delivery system of EO as antibacterial agent for applications in the food industry.