An Independent Evaluation of Alternative Rapid Methods for the Detection of Salmonella in Select Emulsifier Ingredients

Introduction: Salmonella outbreaks from low moisture products (a_w < 0.85) are relatively rare but often impact large numbers of people.  In recent years, a number of these outbreaks has illustrated the point that, while this organism cannot grow in these products, it does have the ability to persist for long periods of time and still cause illness due to its low infectious dose. Many rapid assays have been validated for the detection of Salmonella; however, these validations do not typically include a wide range of low moisture products.  Recent outbreaks highlight the importance to public health that rapid methods are validated for these commodities.  

Purpose: To conduct an initial feasibility evaluation of the performance of AOAC OMA 2013.03 and 2003.09 for ten emulsifiers.  A larger method validation study was conducted on one emulsifier upon completion of the feasibility study. 

Methods: Feasibility Study: For each matrix, 5 replicates at a high contamination level (5-10 CFU/test portion) were evaluated by the alternative RT-PCR methods. Method Validation: Thirty sample replicates (20 low level contamination, 5 high level contamination, 5 uninoculated control) were evaluated in a paired study by the alternative methods and the FDA/BAM Chapter 5. 

Results: Feasibility Study: No issues were observed for 9 of 10 emulsifiers. For one matrix, Panodan 150 LP, no recovery of the analyte from the reference method was observed. Further analysis resulted in a modification to the enrichment media to improve recovery. This matrix was selected for the full validation. Using POD, no statistical significant difference was observed between the alternative and reference method. 

Significance: The data generated in this evaluation indicates that the rapid alternative methods with a modified enrichment media containing a surfactant are a suitable alternative method for the detection and recovery of Salmonella in these select commodities.