Purpose: The purpose of this study was to demonstrate the effectiveness of essential oils with other antimicrobials at lower concentrations in wash water against Salmonella on organic leafy greens.
Methods: Ten-gram samples of organic baby and mature spinaches and romaine and iceberg lettuces were inoculated with antibiotic-resistant Salmonella Newport and dip treated in (a) phosphate buffered saline; (b) 3% hydrogen peroxide; (c) 0.1% cinnamon oil and 3% olive extract combination; and (d) 0.1% oregano oil and 3% olive extract combination. Samples were collected on days 0, 1, and 3 for enumeration of survivors.
Results: From an initial value of 5.0 and 5.3 log CFU/g, baby spinach showed 3.5 and 4.0 log CFU/g reductions on day 3 for the cinnamon oil plus olive extract and oregano oil plus olive extract combinations, respectively. Both combinations induced a 3.0 log CFU/g reduction in mature spinach. For Romaine lettuce, there was 3.0 log CFU/g reduction for the cinnamon oil and olive extract combination, and a 4.0 log CFU/g reduction for the oregano oil and olive extract combination. For iceberg lettuce, the cinnamon oil and olive extract treatment yielded a 2.75 log CFU/g reduction from an initial value of 5.1 log CFU/g, while the oregano oil and olive extract treatment yielded a 3.5 log CFU/g reduction.
Significance: The combination treatments were more effective against S. Newport than individual antimicrobials and, may also help retain the organoleptic attributes of organic leafy greens. Combination antimicrobials have the potential to serve as alternative sanitizer options.