June 2021

Latest validation offers food laboratories additional layer of confidence when testing for Salmonella

The Thermo Scientific™ SureTect™ Salmonella Species PCR Assay receives approval by AOAC International (AOAC-OMA claim) for a broad range of foods and select environmental surfaces, including challenging, high-risk matrices and large sample sizes.

The method was validated against the FDA-BAM, USDA-FSIS and ISO reference methods, giving food laboratories the world over confidence in the robustness of the assay and the accuracy of its results.

The AOAC-OMA claim for the SureTect Salmonella Species Assay covers 32 matrices – currently one of the broadest range of foods and selected environmental surfaces covered for an AOAC-OMA validated Salmonella test. This includes challenging to test high-risk products from a broad range of foods and production environments, such as cocoa products and other low moisture foods, raw meats and poultry meats, fruits & vegetables, milk & dairy products and ready-to-eat foods. The SureTect Salmonella Species PCR Assay is the first to offer a validated method for Salmonella testing in large samples for multiple matrix types such as raw beef meats, produce, cocoa and chocolate.

Meeting customer needs

This news means the SureTect workflow meets more of our customers’ needs than ever.

In the AOAC study, 32 matrices were tested using the SureTect Salmonella Species PCR Assay (candidate method) and the FDA/BAM1, USDA/FSIS2 and ISO3 reference methods. These included 11 foods not previously tested as part of the original AOAC-Performance Tested Methods (PTM) program. These were selected after an audit of currently available methods highlighted a requirement for tools that enabled larger sample size testing and the addition of some of the more challenging and higher-risk products.

The new matrices include 25 g samples of cut cabbage, cut mango, Cheddar cheese, Feta cheese, and cream, as well as up to 375 g ground beef, beef trim, spinach, cocoa powder, cocoa butter, cocoa liquor and dark chocolate (> 70% cocoa). 

The collaborative part of the study was conducted using samples of 375 g cocoa powder. The challenging nature of detecting Salmonella in such samples and large test portions is well documented. In addition, the phenols present in cocoa can inhibit PCR, making it a particularly challenging matrix both in terms of creating the right conditions for the organism to grow, and using PCR to detect it.

Thanks to the assay’s simple workflow and minimal handling steps, the team was able to demonstrate and train collaborator laboratories’ staff on how to use the SureTect Salmonella Species PCR Assay workflow remotely via online training sessions. This approach was necessary for some participants due to COVID restrictions and was well received and highly effective.

The study found no issues in terms of inhibition or false positive/negative data, confirming the robustness of the method in even when used under the most challenging of conditions.

What is OMA?

The Official Methods of Analysis (OMA) is AOAC INTERNATIONAL's premier methods program for evaluating chemistry, microbiology, and molecular biology methods. This First Action secures the SureTect Salmonella Species PCR Assay a place in the AOAC gold-standard compendium of methods.  The globally recognized status also assures compliance with title 21 of the FDA’s Code of Federal Regulations during official controls.

Crucially, the FDA calls for an AOAC-OMA validated method of Salmonella control for foodstuffs being imported into the United States. As such, SureTect Salmonella Species PCR Assay now offers an additional level of confidence in compliance. 

The SureTect Salmonella Species Assay protocol, which was approved in April following a public meeting to discuss the method and results of the validation studies, will be available to subscribers of AOAC-OMA online4 in the coming months.

Daniele Sohier, senior manager, global scientific affairs, at Thermo Fisher, said: “We worked with our food laboratory customers to identify gaps in the existing landscape of validated matrices. These gaps were addressed in our extended pre-collaborative study, during which 32 matrices, 11 of which were new for the SureTect Salmonella Assay, were tested against the FDA, UDSA and ISO reference methods.

“With such a broad range of matrices, our partners can have confidence that the SureTect Salmonella Assay method is validated, robust and reproducible in almost any area of food manufacturing and processing. This covers difficult to test and high-risk products, such as fruits and produce that are often eaten raw, ready-to-eat foods such as most of the dairy products, meat and poultry meat as primary production is a reservoir of Salmonella, and low moisture foods like cocoa and chocolate.  We have also responded to the growing popularity of high-volume testing, by validating matrices for 375 g samples of raw beef meats, produce and multiple cocoa products.

“The OMA validation offers our food laboratory partners an additional level of confidence in their results, their compliance, and the safety of their customers.”

References:

  1. FDA Bacteriological Analytical Manual (BAM), Chapter 5 - Salmonella spp.
  2. USDA/FSIS Microbiology Laboratory Guidebook, Revision 4.10 - Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg, and Siluriformes (Fish) Products and Carcass and Environmental Sponges.
  3. EN ISO 6579-1:2017. Microbiology of the food chain – Horizontal method for detection, enumeration and serotyping of Salmonella – Part 1: Detection of Salmonella spp.
  4. http://www.eoma.aoac.org/ 

 

For more information about the SureTect Salmonella Species PCR Assay visit thermofisher.com/suretect

 

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