P1-30 Comparison between 3M Petrifilm Salmonella Express System and ISO 6579 Conventional Method for the Detection of Salmonella spp. in Cook-chill and Cook-freeze Retail Foods in Bangkok, Thailand

Monday, August 4, 2014
Exhibit Hall D (Indiana Convention Center)
Aphacha Jindaprasert, King Mongkut’s Institute of Technology, Bangkok, Thailand
Asanee Vichitraka, King Mongkut’s Institute of Technology, Bangkok, Thailand
Janejira Fuangpaiboon, 3M Food Safety, 3M Thailand Ltd., Bangkok, Thailand
Nongnuch Promla, 3M Food Safety, 3M Thailand Ltd., Bangkok, Thailand
Adisorn Swetwiwathana, King Mongkut’s Institute of Technology, Bangkok, Thailand
Introduction: Cook-chill and cook-freeze foods have become increasingly common in Bangkok with consumers purchasing these foods via caterers, supermarkets and restaurants. Despite this increasing popularity, the microbial safety of these products — specifically Salmonella contamination — has not been studied extensively

Purpose: The aim of this study is to determine natural contamination rates of Salmonella in cook-chill and cook-freeze foods sold in Bangkok. Additionally, this study aims to evaluate the performance of 3M™ Petrifilm™ Salmonella Express (SALX) System for the detection of Salmonella spp. in various types of cook-chill and cook-freeze foods compared to the standard ISO 6579 conventional method

Methods: Cook-chill (26 samples) and cook-freeze (74 samples) foods were randomly purchased from supermarkets in Bangkok. Fifty grams of each sample was homogenized, divided equally and analyzed following two methods: (1) 3M™ Petrifilm™ SALX System; (2) ISO 6579 using BPW pre-enrichment, MKTTn & RV selective enrichment, and XLD & HE agar for selective plating. Furthermore, five replicates of six different matrices (Salmonella negative samples, n = 30) were spiked with low levels (1–10 CFU/25g) of Salmonella Typhimurium to validate the performance of 3M™ Petrifilm™ SALX System compared to the standard ISO 6579 conventional method. 

Results: Nine samples (8.22%) of cook-freeze foods were naturally contaminated with Salmonella spp. (five samples were positive by both methods; three samples were positive by ISO method only; one sample was positive by 3M™ Petrifilm™ SALX System only). All cook-chill samples were negative (0% natural contamination). For the artificially inoculated samples the relative accuracy, relative sensitivity and relative specificity of the 3M™ Petrifilm™ SALX System was found to be 96.9%, 92.1% and 98.9%, respectively.

Significance: The data from this study supports the use of 3M™ Petrifilm™ SALX System as a rapid and cost-effective method for Salmonella detection in cook-chill and cook-freeze foods.