Anti-listerial effect of selected essential oils and thymol

Area of Science:

• Food Microbiology
• Natural Product Chemistry
• Food Safety

Background:

• Listeria monocytogenes is a significant foodborne pathogen, posing risks to chicken products.
• Natural antimicrobials like essential oils (EOs) and thymol are explored for food preservation.
• Pre-treatment methods like washing may influence the efficacy of antimicrobial interventions.

Purpose of the Study:

• To evaluate the anti-listerial efficacy of marjoram and thyme essential oils (EOs) and thymol.
• To assess their impact on Listeria monocytogenes in inoculated chicken breast fillets.
• To determine the influence of pre-washing and marination on microbial counts and sensory attributes.

Main Methods:

• Chicken breast fillets were inoculated with Listeria monocytogenes and either washed or not.
• Fillets were marinated in solutions containing salt (5%) and specific concentrations of marjoram EO, thyme EO, or thymol.
• Total germ count (TGC) and Listeria monocytogenes counts were monitored on fillets and in marinades after 24 and 48 hours at 6 °C.

Main Results:

• Thyme essential oil and thymol significantly reduced Listeria monocytogenes counts by 1-3 log CFU in both washed and unwashed samples.
• The essential oils and thymol imparted a pleasant flavor to the fried chicken.
• Pre-washing the chicken fillets was not effective in reducing the total germ count.

Conclusions:

• Thyme essential oil and thymol are effective natural antimicrobials against Listeria monocytogenes in chicken breast.
• These compounds offer a dual benefit of pathogen reduction and flavor enhancement.
• Washing is an ineffective pre-treatment for reducing microbial load on chicken fillets in this context.