|Rada, Zeeroy - University Of Arizona|
|Tood-searle, Jennifer - University Of Arizona|
|Jaroni, Divya - Oklahoma State University|
|Ravishankar, Sadhana - University Of Arizona|
Submitted to: Journal of Food Safety
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2016
Publication Date: 2/12/2016
Citation: Rada, Z., Tood-Searle, J., Friedman, M., Patel, J.R., Jaroni, D., Ravishankar, S. 2016. Combining essential oils and olive extract for control of multi-drug resistant Salmonella enterica on organic leafy greens. Journal of Food Safety. 1(2):1-9.
Interpretive Summary: The consumption of organic produce has increased dramatically over the past several years. A potential issue is the limited number of treatment options to control pathogen contamination on organic produce. We evaluated the antimicrobial effect of several GRAS (generally recognized as safe) plant essential oils against Salmonella on organic fresh produce, including romaine and iceberg lettuce, and adult and baby spinach. Fresh produce leaves inoculated with Salmonella Newport (1 million cells/g) were immersed in 0.1% cinnamon oil and 3.0% olive extract, or 0.1% oregano oil and 3.0% olive extract. Samples were collected on days 0, 1, and 3 for enumeration of surviving Salmonella cells. Salmonella populations were reduced by 10,000-fold on baby spinach and romaine lettuce, and 1000- to 5000-fold on mature spinach or iceberg lettuce. This study demonstrates the potential of essential oils to reduce S. Newport on organic leafy greens. This information will be useful to other scientists and to the organic produce industry.
Technical Abstract: We investigated the combined antimicrobial effects of plant essential oils and olive extract against antibiotic resistant Salmonella enterica serovar Newport on organic leafy greens. Organic baby spinach, mature spinach, romaine lettuce, and iceberg lettuce were inoculated with S. Newport and dip-treated in phosphate buffered saline control, 3.0% hydrogen peroxide, 0.1% cinnamon oil and 3.0% olive extract or 0.1% oregano oil and 3.0% olive extract combination treatments. Samples were collected on days 0, 1, and 3 for enumeration of survivors. Up to 3.5-4 logs and 3-4.4 logs CFU/g reductions in Salmonella population on baby spinach and romaine lettuce, respectively, were observed when treated with both combinations. Similarly, these treatments reduced Salmonella by 3 logs CFU/g on mature spinach. The cinnamon oil and olive extract treatment yielded about 3.0 logs CFU/g reduction, while the oregano oil and olive extract treatment yielded about 3.5 logs CFU/g reduction in Salmonella population on iceberg lettuce.