Antimicrobial efficacy of plant essential oils against foodborne pathogens in dairy products

Abstract:

While synthetic preservatives effectively extend dairy shelf life, growing consumer demand for clean-label products has driven interest in plant-derived antimicrobials. This research evaluated the antibacterial activity of five essential oils cinnamon bark, thyme, oregano, clove bud, and lemongrass against five foodborne pathogens (Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 25923, Listeria monocytogenes ATCC 19115, Salmonella typhimurium ATCC 14028, and Bacillus cereus ATCC 11778) using disc diffusion, Minimum Inhibitory Concentration (MIC), and Minimum Bactericidal Concentration (MBC) assays. Cinnamon bark oil exhibited the strongest activity, with MIC values of 0.125-0.5 µL/mL across all five pathogens. When incorporated into paneer at 0.1% and 0.2% (v/w), cinnamon and thyme oils reduced E. coli counts by 2.3 and 1.8 log₁₀ CFU/g, respectively, after 7 days at 4 °C compared with untreated controls. Sensory evaluation indicated that 0.1% cinnamon oil was organoleptically acceptable, while the 0.2% level imparted a noticeable flavour. These findings position cinnamon and thyme essential oils as promising natural preservatives for fresh dairy products at concentrations that balance microbial safety with consumer acceptability.