Anti-Microbial Potential of Nano-Emulsion form of Essential Oil Obtained from Aerial Parts of Origanum Vulgare L. as Food Additive

Foodborne diseases are still a serious problem in public health and natural compounds are being widely considered for their potential industrial protective additive in food products. Origanum vulgare L. has been known as an antimicrobial effective herb. This present study was carried out to examine the antimicrobial effect of O. vulgare essential oil nanoemulsion in comparison with conventional emulsion.

The essential oil was obtained by hydrodistillation, analyzed by GC-Mass and formulated as a nanoemulsion to improve water dispersion by high-energy emulsification method. The antimicrobial activity of the prepared formulation was assessed by measuring the minimum inhibitory concentration (MIC), minimum bactericidal/fungicidal concentration (MBC/MFC) and zone of inhibition against some main foodborne pathogen microorganisms.

The main component of the oregano essential oil was carvacrol (78%) and the selected nanoemulsion formulation demonstrated low polydispersity (0.11) and mean droplet (72.26 nm) and it was stable even after 30 days of storage. The nanoemulsion form displayed significant activity against the S. aureus, C. albicans and A. niger with inhibition zones ranging from 8.7–22.3mm. The MIC of nanoemulsion against the tested bacteria was within the range of 0.156 to 0.312 (mg/ml) and against the tested fungi were in the range of 0.078 to 0.156 (mg/ml). The MBC/MFC of nanoemulsion against the tested microorganisms were in the range of 0.312 to 5 (mg/ml).

The study's results demonstrated the possibility of using the nanoemulsion form of oregano essential oil as a food additive to inhibit the growth of some foodborne microorganisms and extending the shelf life of food products.