Milk preservation: Enhancing the anti- Staphylococcus aureus potency using essential oils specific mixture

This study aims to calculate the optimal formula combining Syzygium aromaticum, Cinnamomum zeylanicum, Myrtus communis, and Lavandula stoechas essential oils to enhance their anti-Staphylococcus aureus effects. Firstly, a chemical analysis of essential oils (EOs) was assessed. Secondly, their antibacterial activities were screened against several bacterial strains with a special emphasis on S. aureus one. Finally, a specific mixture design plan was elaborated to determine the combination presenting the highest protection against S. aureus. Thus, the complex simplex-centroid mixture design was adopted to build polynomial models detailing the relationship between the anti-S. aureus activity and the proportion of each essential oil. Obtained results indicated compositional variabilities between studied samples. Indeed, the major compounds were camphor (35%), α-pinene (75%), cinnamaldehyde (89%) and eugenol (75%) for lavender, myrtle, cinnamon, and clove EOs, respectively. Additionally, the antibacterial activity test illustrated that all studied EOs were potent antimicrobial agents especially cinnamon and clove ones (from 15 to 39 mm inhibition zone). The search for the most effective combination for milk preservation against S. aureus suggested that a mixture of 58.8% cinnamon, 34.4% clove, and 6.8% lavender presents the optimal efficiency (reduction to 1 ± 0.1 × 106 CFU.ml−1). Thereby, this formula could be considered as a potential alternative for food safety against S. aureus contamination, particularly in milk and dairy industries.