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ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #362966
Research Project: Characterization and Mitigation of Bacterial Pathogens in the Fresh Produce Production and Processing Continuum

Location: Environmental Microbial & Food Safety Laboratory

Title: Nanoemulsified carvacrol as a novel washing treatment reduces Escherichia coli O157:H7 on fresh produce

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

Submitted to: BARC Poster Day
Publication Type: Abstract Only
Publication Acceptance Date: 4/5/2019
Publication Date: 4/24/2019
Citation: Chen, C., Hsin-Bai, Y., Byun, S., Zi, T., Luo, Y., Patel, J.R. 2019. Nanoemulsified carvacrol as a novel washing treatment reduces Escherichia coli O157:H7 on fresh produce. BARC Poster Day. 10:25.

Interpretive Summary:

Technical Abstract: Fresh produce continues to be the main source of foodborne illness outbreaks in the United States implicating bacterial pathogens such as Escherichia coli O157:H7 (EHEC). The efficacy of nanoemulsified carvacrol, a natural phytochemical, as washing treatments in reducing EHEC on fresh produce was investigated. Fresh spinach, Romain lettuce, and Iceberg lettuce leaves (3 cm diameter cores; N=216) 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 alone, 25 or 50 ppm free chlorine, and 0.25% or 0.75% carvacrol nanoemulsion (CRN) for 2 minutes, followed by rinsing with 100 ml neutralizing broth for 30 s and drying in spinning salad bowl for 1 minute. Inoculated produce leaves without any treatment was included as baseline. Produce leaves were stored at 10°C and surviving EHEC populations were enumerated on days 0, 2, 7 and 14 by plating on CT-Sorbitol MacConkey agar supplemented with Cefixime, potassium tellurite and nalidixic acid. CRN at 0.75% 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 (P<0.05). 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). Results of this study support the potential use of CRN as water soluble antimicrobial washing treatments for controlling EHEC on fresh produce.