Characterization and Synergistic Antifungal Evaluation of a Food Grade Microemulsion System against Aspergillus flavus

In this study, we aim to study the possibility of enhancing the antifungal application of microemulsions in food industry. The physicochemical properties of multi-component microemulsions containing Cinnamon Essential Oil (CEO), ethanol, Tween 80, water and lactic acid have been studied. Lactic acid showed positive effect on oil solubilization and the formation of U-type microemulsion. Four microemulsion formulations were selected and used for particle size distribution and viscosity measurements. The synergistic antifungal effects of CEO and lactic acid on Aspergillus flavus were studied by measurements of Fractional Inhibitory Concentration Index (FICI). Antifungal tests suggested that the microemulsions inhibited the viable fungal spores and the mycelium growth effectively as the Minimal Inhibitory Concentration (MIC) of the microemulsions ranged from 4 mg/mL to 11 mg/mL. The addition of lactic acid in CEO/ethanol/Tween 80/water system also greatly improved the antifungal activity of microemulsions. It was found that the CEO had synergistic antifungal activities in combination with lactic acid for the value of FICI was ranged from 0.30 to 0.35. This study shows the possibility of enhancing the antifungal application of microemulsions in food industry.