Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #361186

Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: Carvacrol nanoemulsion controls Escherichia coli O157:H7 on fresh produce

Author
item CHEN, CHI-HUNG - US Department Of Agriculture (USDA)
item YIN, HSIN-BAI - US Department Of Agriculture (USDA)
item BYUN, SUYEUN - US Department Of Agriculture (USDA)
item ZI, TENG - US Department Of Agriculture (USDA)
item LUO, YAGUANG - US Department Of Agriculture (USDA)
item Patel, Jitu

Submitted to: International Association for Food Protection
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2019
Publication Date: 4/24/2019
Citation: Chen, C., Yin, H., Byun, S., Zi, T., Luo, Y., Patel, J.R. 2019. Carvacrol nanoemulsion controls Escherichia coli O157:H7 on fresh produce. International Association for Food Protection. 10:25.

Interpretive Summary:

Technical Abstract: Abstract Introduction: Fresh produce has been implicated in recent foodborne illness outbreaks associated with the consumption of Escherichia coli O157:H7 (EHEC). Purpose: We investigated the efficacy of nano-emulsified carvacrol, a natural phytochemical, as a wash treatment for reducing EHEC on fresh produce. Methods: Fresh spinach, Romain lettuce, and Iceberg lettuce leaf cores (3 cm diameter, 216 samples) were spot-inoculated with 25 µl of a five-strain cocktail of nalidixic acid (NA) resistant EHEC at 8 log CFU/ml. After air-drying for 1 h, 20 pieces of each inoculated produce leaves were immersed in water-based treatment solutions (200 ml/group), including water, 25 or 50 ppm free chlorine, and 0.25% or 0.75% (w/w) carvacrol nanoemulsion (CRN) for 2 minutes, followed by rinsing with 100 ml neutralizing broth for 1 min and drying in spinning salad bowl for 1 min. Inoculated produce leaves without any treatment were served as baseline. Produce leaves were stored at 10°C and EHEC populations were enumerated on days 0, 2, 7 and 14 by plating on CT-Sorbitol MacConkey agar with NA. Results: A 0.75% CRN wash treatment significantly reduced EHEC populations on spinach, Iceberg lettuce, and Romain lettuce to 3.6 log, 4.0 log, and 4.5 log CFU/cm2, respectively, compared to ~ 6.0 log CFU/cm2 of EHEC recovered from the baseline on day 0. During storage, the antimicrobial activity of CRN against EHEC was more pronounced on Romain lettuce, followed by Iceberg lettuce and spinach; populations of EHEC on Romain lettuce were reduced by 4.0 log CFU/cm2 as compared to the baseline after 14 days. Antimicrobial properties of CRN at 0.75% against EHEC were superior to 25 and 50 ppm chlorine on both lettuces on day 14 (P<0.05). Significance: Results of this study support the potential use of CRN as water-soluble antimicrobial washing treatment for controlling EHEC on fresh produce.