Location: Environmental Microbial & Food Safety Laboratory
Title: Carvacrol nanoemulsion controls Escherichia coli O157:H7 on fresh produceAuthor
CHEN, CHI-HUNG - US Department Of Agriculture (USDA) | |
YIN, HSIN-BAI - US Department Of Agriculture (USDA) | |
BYUN, SUYEUN - US Department Of Agriculture (USDA) | |
ZI, TENG - US Department Of Agriculture (USDA) | |
LUO, YAGUANG - US Department Of Agriculture (USDA) | |
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. |