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Essential Oil Microemulsions Inactivate Antibiotic-Resistant Bacteria on Iceberg Lettuce during 28-Day Storage at 4
Stephanie Arellano1, Libin Zhu1, Govindaraj Dev Kumar2
1School of Animal and Comparative Biomedical Sciences, University of Arizona, 1117 E. Lowell Street, Tucson, AZ 85721, USA.
Molecules (Basel, Switzerland)
|October 14, 2022
Summary
Essential oil microemulsions effectively reduce harmful bacteria like Escherichia coli O157:H7 and Pseudomonas fluorescens on Iceberg lettuce. These natural treatments offer a promising alternative to chemical decontamination for leafy greens.
Area of Science:
- Food Science
- Microbiology
- Agricultural Science
Background:
- Contamination of leafy greens with foodborne pathogens like Escherichia coli O157:H7 and Pseudomonas fluorescens poses a significant public health risk.
- Conventional decontamination methods, such as chlorine and hydrogen peroxide, can have environmental drawbacks and may affect produce quality.
- There is a growing demand for natural, eco-friendly, and effective antimicrobial agents in the food industry.
Purpose of the Study:
- To evaluate the antimicrobial efficacy of essential oil-based microemulsions against E. coli O157:H7 and P. fluorescens on Iceberg lettuce.
- To compare the effectiveness of oregano, lemongrass, and cinnamon oil microemulsions with conventional sanitizers.
- To assess the impact of microemulsions on the visual appeal and quality of treated lettuce during storage.
Main Methods:
- Iceberg lettuce was inoculated with E. coli O157:H7 or P. fluorescens.
- Lettuce samples were treated with a control, chlorine, hydrogen peroxide, or varying concentrations (0.1%, 0.3%, 0.5%) of essential oil microemulsions.
- Treated samples were stored at 4°C and analyzed for bacterial populations at multiple time points over 28 days.
Main Results:
- Essential oil microemulsions demonstrated concentration- and storage-time-dependent reductions in both E. coli O157:H7 (1.26–4.86 log CFU/g) and P. fluorescens (0.32–2.35 log CFU/g).
- Oregano oil microemulsion (0.1%) improved the visual appeal of lettuce inoculated with E. coli O157:H7.
- Cinnamon (0.5%) and oregano (0.3%) oil microemulsions showed significant potential for decontamination, outperforming some chemical treatments in specific aspects.
Conclusions:
- Essential oil-based microemulsions, particularly cinnamon and oregano oils, are effective natural alternatives for reducing E. coli O157:H7 and P. fluorescens on leafy greens.
- These microemulsions offer a promising eco-friendly approach to food safety, enhancing the decontamination of produce.
- Further research into optimizing microemulsion formulations could lead to widespread adoption in the leafy green industry.
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