IAFP 2009 Program Book and Abstract Book - AB144

P2-108 Internal and Independent Laboratory Validation of PCR Assays for Detection of L. monocytogenes from Both Food and Stainless Steel Surfaces STEPHEN VARKEY, Dawn Fallon, Daniel DeMarco and Robert Jechoreck DuPont, Wilmington, DE, USA Introduction: Listeria monocytogenes was characterized more than 75 years ago as a causative agent of disease in animals, but only within the past 20 years has it been widely recognized as an important cause of human foodborne illness. Sensitive methods with faster time to result are needed so that interventions strategies may be implemented more rapidly. Purpose: Internal and external studies were conducted to evaluate a new PCR assay for the rapid detection of L. monocytogenes using a single proprietary enrichment for next-day results. Methods: For various spiked foods and stainless steel surfaces, one set of twenty spiked replicates and five unspiked controls per matrix were enriched for 18 to 20 hours in 24E broth, then tested with the 24E L. monocytogenes assay, using the PCR-based BAX® system. A second set of replicates was tested according to an appropriate reference method. Additionally, 50 L. monocytogenes and 50 non-L. monocytogenes were tested for inclusivity and exclusivity. Results: The internal studies showed that the L. monocytogenes PCR method, across all five foods/surfaces and organisms, detected 79/120 samples with next- day results compared to 67/120 for the reference method (~5 days). Of the 120 samples, 82 were confirmed for L. monocytogenes. The external studies on stainless steel showed that the PCR method detected 14/20 versus 17/20 for the reference method. Of the 14 PCR positives, 14 were confirmed as L. monocytogenes. For hot dogs. the PCR method detected 10/20 versus 14/20 for the reference method. All unspiked samples were negative by PCR and culture. One-hundred percent inclusivity and exclusivity was observed. The aggregate internal data indicates that the L. monocytogenes PCR method was statistically equivalent (Χ2 = 2.50) to the reference method. Significance: The PCR assay performance is equivalent to reference culture methods, but with faster time to results, it can enable intervention strategies to be implemented more rapidly. P2-109 Development of Multiplex PCR Analysis for Detection of Major Peanut (ARA H 1), Hazelnut (COR A 1) and Almond (PRU DU 2.02) Allergens in Food Products EVA RENCOVA and Zora Hubalkova Veterinary Research Institute, Analytical Biotechnology, Brno, Czech Republic Introduction: People suffering from food allergies are dependent on accurate food labelling to prevent the allergic reaction. The detection of the main peanut (Arachis hypogaea ) allergen Ara h 1, hazelnut (Corylus avellana) allergen Cor a 1 and almond (Prunnus dulcis) allergen Pru du 2.02 represents the tool of regular food labelling authentication. Purpose: The purpose of this study was to develop a multiplex PCR method for the detection of three major food allergens (peanut, hazelnut, and almond). Declared and nondeclared food products were investigated for the presence of these allergen residues. Methods: Three sets of primers for the amplification of the partial genomic sequence of the Ara h 1 (180 bp), Cor a 1 (397 bp) and Pru du 2.02 (249 bp) genes were designed and applied to the investigation of 72 commercial food samples with or without peanut, hazelnut or almond declaration. The specificity of primer pairs was tested. The universal plant primers for the plant matrixes confirmation in food (123 bp) were used. Results: Thirty samples of food products with hazelnuts, thirteen with peanuts, eight with almonds, 18 without declaration and three with common declaration as nuts were analyzed using the developed PCR method. In non-declared samples no hazelnuts, peanuts or almonds were detected. The detection limit of the method was 0.01%, for hazelnut and almonds, and 1% for peanuts. Significance: The developed multiplex PCR method is specific enough to detect peanut, hazelnut and almond major allergens simultaneously in food products. Financially supported by grants MZe 00027 16201 and QG 60090/2005. P2-110 Prevalence of Bacillus cereus in Fried Rice Dishes and Its Exposure Assessment from Chinese-style Restaurants in Korea HYE-JA CHANG, Bo-ra Han, Ji-hye Lee, Eun-seon Go, Jun Kim, Gang-gweon Lee and Tong-kyung K. Yum Dankook University, Food Science and Nutrition, Gyeonggi-do, Korea, South Introduction: To conduct a risk profile for Bacillus cereus in fried rice dishes, data on the prevalence of B. cereus as well as an exposure assessment are needed. Fried rice dishes are one of the most popular food items in Korea; however, there are no data on the exposure pathway and contamination level of B. cereus in those dishes. Purpose: This study aimed to produce an exposure assessment for fried rice dishes and to evaluate the microbiological quality of these foods from Chinese-style restaurants. Methods: The exposure pathway for fried rice was assessed in terms of time, temperature and serving size by phases from preparation to consumer consumption point, through on-site observation at 8 Chinese-style restaurants in Gyeonggi province. The microbiological quality of 32 samples of fried rice delivered from restaurants was evaluated for the levels of B. cereus, ACC, and Coliforms. Chromogenic Bacillus cereus agar was used for the presumptive test of B. cereus, and real-time PCR was performed with TMC-1000 system for the confirmation test. Results: One serving size of fried rice dishes was 352.2 g. In 3 restaurants that reheat pre-cooked rice dishes, mean temperature of the dishes after the reheating phase was 68.5°C, and the final cooking time was 1 min 14 s. Meanwhile, mean temperature of fried rice dishes in 5 cook-to-order type restaurants was 81.4°C, with 1 min 49 s of cooking time. Average meal assembly time was measured as 1 min 20 s. Average delivery time from restaurant to place of consumption was approximately 12 min. The mean temperature of fried rice dishes at the consumption point was 66.1°C for cook-toorder restaurants, and 59.8°C in counterpart restaurants with a reheating process. The prevalence of B. cereus detected in cooked rice at the consumption point was 37.5%. Especially, 31.3% of samples were contaminated at levels higher than the microbial standard of 103 CFU/g specified guidelines in the Korea Food Code for B. cereus of 103 CFU/g. 144 — Abstract Book Poster

IAFP 2009 Program Book and Abstract Book

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