Lemon Essential Oil Versus Listeria in Beef

By: Arnold Bustillo, MSc Aromatherapy

Center photo by Lukas from Pexels.com

The following is NOT MEDICAL ADVICE and is intended for educational purposes only - to illustrate the science behind essential oils, how they might be applied in the real world, and to offer a foundation from which to speak to your doctor or registered aromatherapist.
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Consult your primary care provider or a registered aromatherapist before using essential oils.

Essential oils are concentrated plant extracts and SHOULD NOT be handled by anyone unaware of the RISKS and DANGERS they pose.

Introduction

One of the biggest problems facing the food industry today is shelf life. With shelf life having a direct impact on the bottom line, food manufacturers and vendors have a tangible motivation to seek new and cost effective ways to increase shelf life of various food products. Maintaining the shelf life of meat products is especially important because aging meat products are literal breeding grounds for a host of foodborne pathogens. One such pathogen is Listeria monocytogenes, commonly referred to as listeria.

Risks of Listeria

According to the United States Centers for Disease Control and Prevention (CDC), the listeria bacteria can cause a sickness known as listeriosis, which is most likely to affect pregnant women and their newborn children, elder adults (aged 65 plus), and the immunocompromised. The CDC lists symptoms of listeriosis to include fever, diarrhea, stiff or aching muscles, fatigue, confusion, convulsions, and in extreme cases (such as when the bacteria spreads beyond the gut into the bloodstream, up to the brain, or into a fetus), can lead to death (Centers for Disease Control and Prevention, 2016).

Lemon Essential Oil

In a study conducted by researchers from Tunisia and Saudi Arabia, Citrus limon, commonly referred to as lemon, essential oil was obtained from the flowers of the lemon plant. While the chemical composition of lemon essential oil can vary depending on region and weather, the sample obtained by the researchers in this case was dominated by two primary chemicals; limonene, which accounted for 39.74% of the essential oil, and B-pinene, which accounted for 25.44% of the essential oil (Ben Hsouna, Ben Halima, Smaoui, and Hamdi, 2017).

Laboratory Testing

To determine the efficacy of the collected lemon essential oil against the listeria bacteria, researchers exposed samples of freshly slaughtered beef to live samples of the bacteria. Five samples were prepared in triplicate, but two of those samples were exposed to a synthetic preservative, so they will not be discussed here. Of the three remaining samples, one beef sample was a control (treated with no preservatives), one beef sample was treated with .06 milligrams of lemon essential oil per gram of meat, and one beef sample was treated with .312 milligrams of lemon essential oil per gram of meat (Ben Hsouna, Ben Halima, Smaoui, and Hamdi, 2017).

Listeria Exposure After Two Days

All three samples were exposed to an equal amount of the listeria bacteria, an amount referred to as 2.5 culture forming units (CFUs) in the published study. Each sample of meat was monitored for 10 days. By day two, the amount of listeria CFUs in the control sample increased from the original 2.5 to about 4 CFUs. Also on day two, the meat samples treated with lemon essential oil both recorded a steady number of CFUs between about 2 and 2.5 (Ben Hsouna, Ben Halima, Smaoui, and Hamdi, 2017).
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In other words, after two days of exposure, the untreated control beef sample experienced an increase in listeria bacteria, but the beef samples treated with lemon essential oil experienced no significant change in the amount of bacteria present.

After Four and Six Days

On day four of observation, the beef sample treated with .312 milligrams of essential oil per gram of meat recorded a significant drop to no significant levels of the listeria bacteria, and would continue to record no significant levels of the bacteria for the remainder of the 10 day observation period.

On day six of observation, the beef sample treated with .06 milligrams of essential oil per gram of meat recorded a similar significant drop to no significant levels of the listeria bacteria, and would continue to record no significant levels of the bacteria for the remainder of the 10 day observation period.

On days four and six of observation, the untreated control sample of beef recorded between 4 and 4.5 CFUs of the listeria bacteria.

(Ben Hsouna, Ben Halima, Smaoui, and Hamdi, 2017)

After 10 Days

By the final day of the 10 day observation period, the untreated control sample of beef recorded about 5 CFUs of the listeria bacteria — essentially doubling the amount of listeria in the beef sample after just 10 days of observation. The beef samples exposed to the lemon essential oil, however, continued to record no significant levels of the bacteria (Ben Hsouna, Ben Halima, Smaoui, and Hamdi, 2017).

This implies that not only can lemon essential oil reduce listeria in beef to less than significant levels, but it can keep listeria at bay for up to 10 days.

Final Comments

To view the full study as published by researchers, please visit the link in the sources below. The explanation of the study presented here is a simplification to illustrate the fact that essential oils are not a pseudoscience, but have serious, scientifically tested benefits for the real world.

Sources

Ben Hsouna, A., Ben Halima, N., Smaoui, S., & Hamdi, N. (2017). Citrus lemon essential oil: chemical composition, antioxidant and antimicrobial activities with its preservative effect against Listeria monocytogenes inoculated in minced beef meat. Lipids in health and disease, 16(1), 146. https://doi.org/10.1186/s12944-017-0487-5
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Centers for Disease Control and Prevention. (2016, December 12). Questions and answers. Centers for Disease Control and Prevention. Retrieved October 2, 2021, from https://www.cdc.gov/listeria/faq.html.