Formulation and characterization of betel leaf (Piper betle L.) essential oil based nanoemulsion and its in vitro antibacterial efficacy against selected food pathogens

The current study is focused on the formulation and characterization of oil-in-water nanoemulsion of betel leaf (Piper betle L.) essential oil and its antibacterial efficacy. The nanoemulsion consists of essential oil of betel leaf as the dispersed phase, distilled water as a continuous phase and a nonionic surfactant Tween 20 (Polysorbate 20) as an emulsifier. Six emulsions were formulated varying the oil to surfactant ratio (vol/vol) from 1:1 to 1:6, using high-energy emulsification process. Three samples, that is, S-2=1:2 (3% EO, 6% Tween 20), S-3=1:3 (3% EO, 9% Tween 20), and S-4=1:4 (3% EO, 12% Tween 20) shown droplet diameter of 508, 70 +/- 12, and 175 +/- 7 nm, respectively. The formulated nanoemulsions showed antimicrobial activity as minimum inhibitory concentration (MIC) of 0.5-1.25 mu l/ml and minimum bactericidal concentration (MBC) of 1-2.5 mu l/ml against five strains of gram-positive and gram-negative bacteria. The formulated nanoemulsions thus can serve as natural antimicrobial agent for food system. Practical applicationThis study can be useful in understanding the potential of essential oil from plant sources in foodprocessing. It can also be helpful to formulate nanoemulsion from essential oil and its characterization. From characterization, researchers can get the knowledge about changes in the morphological characteristics of the nanoemulsion and also other physical properties. The thermodynamic and kinetic stability study of the nanoemulsions can give us an idea about the application in different food processing and preservation conditions. Furthermore, the use of essential oil in the food industry is mainly as a flavouring agent. Based on the antibacterial efficacy of the formulated nanoemulsions, it can also be utilized as a potential natural class one preservative.