Microbiological evaluation of Vietnamese Pho ingredients in Toronto

Abstract

Introduction: Beef and bean sprouts have often been implicated in foodborne illness (FBI) outbreaks. The traditional Vietnamese dish, Pho, uses both as its main ingredients and, therefore, presents significant concerns from a food safety perspective. The present study investigated food safety concerns associated with Pho through the detection of total coliform and Escherichia coli. Methods: Thirty-two Vietnamese restaurants in Toronto, Ontario, Canada, were selected for the study based on inclusion criteria. All restaurant operators were briefed prior to sampling and were informed that their consent and participation were voluntary. Fourteen restaurants consented to providing samples and allowing their broth temperatures to be taken. Three types of samples were obtained from each location: raw beef (RB), cooked beef (CB), and bean sprouts (BS). All samples were couriered to an accredited laboratory for microbiological analysis via 3M petrifilm E. coli/coliform count plates. Based on reported total coliform count (TCC), locations were segmented into low, medium, and high contamination categories. Subsequent correlational analysis were conducted based on lab detection data to identify potential links between E. coli count (ECC) and TCC, TCC and broth temperature, and ECC and broth temperature. In addition, an ANOVA was performed to examine for differences in TCC by sample types, differences in TCC by suppliers, differences in ECC by sample types, differences in ECC by suppliers, and differences in TCC by location types. Results: ANOVA indicated a significant effect of sample type on TCC for all three different sample types, with post hoc comparisons elucidating significantly lower TCC in CB and RB samples, compared with BS samples. Subsequent analysis further indicated the significant effect of location category on TCC, with post hoc comparisons demonstrating significantly higher TCC in Category 3 locations compared to Category 1 and 2 locations. All other analysis yielded nonstatistically significant results. Conclusion: This study presented significant findings in linking Pho ingredients to potential food safety concerns. Specifically, temperature control was identified as a possible cause for high TCC and E. coli detection at select restaurants. Although analysis involving E. coli did not yield any significant results, any E. coli found on ready-to-eat food at a restaurant is problematic from a food safety perspective. Based on the results, we recommended policy changes to incentivize restaurants to maintain high hygienic standards and improve efficiency of the public health inspection process.