Microemulsions of clove, tea tree and cinnamon using different tweens: physical properties and antimicrobial activity against E. coli O157:H7

Escherichia coli O157:H7, a major pathogenic bacterium with a high impact on public health and increased antibiotic resistance, has been a significant concern. In this context, essential oil emulsions (EOEs) have emerged as a promising alternative for treating such pathogenic bacteria. Our study aimed not only to characterize Tea Tree Oil (TTO), Clove Oil (CLO), and Cinnamon Oil (CO) emulsions but also to evaluate their activity against E. coli O157:H7. The emulsions, prepared by mixing 10% v/v of each oil with 3% Tween 20 or 80 v/v and subjected to ultrasonication for 15 min, were then characterized by dynamic light scattering. The antimicrobial activity was determined by the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). The results suggested that CO with Tween 20 was stable regarding particle size, polydispersity index, and Z potential, as a difference was not found (p > 0.05) from day 0 to day 28 among them. On the other hand, CO with Tween 80 showed or tended to show apparently lower MIC (0.85 mg/mL) and MBC (0.95 mg/mL) than those of the rest of the emulsions. These promising findings indicate that the essential oil emulsions of Cinnamon oil had good stability and significant potential to be used as an alternative to treat pathogenic bacteria.