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Rapid Detection of Escherichia coli in Fresh Foods Using a Combination of Enrichment and PCR Analysis
Korean J. Food Sci. An. 2018;38:829-834
Published online August 31, 2018;  https://doi.org/10.5851/kosfa.2018.e19
© 2018 Korean Society for Food Science of Animal Resources

Yukyung Choi1,2, Sujung Lee1,2, Heeyoung Lee1,2, Soomin Lee1,2, Sejeong Kim1,2, Jeeyeon Lee1,2, Jimyeong Ha1,2, Hyemin Oh1,2, Yewon Lee1,2, Yujin Kim1,2, and Yohan Yoon1,2,*

1Department of Food and Nutrition, Sookmyung Women’s University, Seoul 04310, Korea
2Risk Analysis Research Center, Sookmyung Women’s University, Seoul 04310, Korea
Correspondence to: Yohan Yoon
Department of Food and Nutrition, Sookmyung Women’s University, Seoul 04310, Korea
Tel: +82-2-2077-7585
Fax: +82-2-710-9479,
E-mail: yyoon@sookmyung.ac.kr
Received May 1, 2018; Revised July 15, 2018; Accepted July 22, 2018.
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Abstract
The objective of this study was to determine the minimum enrichment time for different types of food matrix (pork, beef, and fresh-cut lettuce) in an effort to improve Escherichia coli detection efficiency. Fresh pork (20 g), beef (20 g), and fresh-cut lettuce (20 g) were inoculated at 1, 2, and 3 Log CFU/g of Escherichia coli. Samples were enriched in filter bags for 3 or 5 h at 44.5℃, depending on sample type. E. coli cell counts in the samples were enriched in E. coli (EC) broth at 3 or 5 h. One milliliter of the enriched culture medium was used for DNA extraction, and PCR assays were performed using primers specific for uidA gene. To detect E. coli (uidA) in the samples, a 3–4 Log CFU/mL cell concentration was required. However, E. coli was detected at 1 Log CFU/g in fresh pork, beef, and fresh-cut lettuce after 5, 5, and 3-h enrichment, respectively. In conclusion, 5-h enrichment for fresh meats and 3-h enrichment for fresh-cut lettuce in EC broth at 44.5℃, and PCR analysis using uidA gene-specific primers were appropriate to detect E. coli rapidly in food samples.
Keywords : fresh meat, fresh-cut lettuce, Escherichia coli, enrichment, PCR


August 2018, 38 (4)