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their heat processed, low-moisture products do not become contaminated after processing through the addition of additives if the food comes in contact with contaminated material [3]. The Solus One Salmonella immunoassay test kit is designed to detect Salmonella in select foods, including low moisture products, following enrichment of the food matrix. The method utilizes antibodies bound to the wells of microplate strips that are specific to Salmonella antigens and detects both motile and non-motile Salmonella . Heat inactivated/lysed sample enrichments are added to the wells of the plate and analysis is conducted following a manual or a fully automated protocol on the Dynex DS2 ® instrument. Results are based on optical density levels resulting from a color change reaction in the wells. Presumptive positive or negative results can be obtained in as little as 22 hours for most food samples and 18 hours for environmental samples. Prior to the collaborative study, the Solus One Salmonella assay was validated according to the current AOAC Guidelines [4] in an AOAC ® Performance Tested Method SM (PTM) study. The Solus Salmonella assay was awarded PTM certificate 101801 in October of 2018 for six food matrices; raw beef trim (375 g), instant non-fat dry milk powder (NFDM, 375 g), pasteurized liquid egg (100 g), raw salmon (25 g), cheddar cheese (25 g), romaine lettuce (25 g), and two environmental surfaces (stainless steel and polystyrene). Since the original study, a level 3 method modification was performed and approved (8-1-19). The level 3 method modification was conducted to include the following: honey mustard seasoning (375 g), flavored ranch seasoning (375 g), cinnamon powder (25 g), paprika powder (25 g) and whole black peppercorns (25 g). See Table 1 below for an overview of the previously validated matrixes for PTM certification. Table 1. PTM Validation Study Summary for the Solus One Salmonella Assay

Solus One Salmonella – PTM 101801

Original PTM Certificate Issued 1

Enrichment Media/Dilution

Enrichment Time (h)

Enrichment Temp (°C)

Reference Method

Matrices

Sample size

Instant NFDM powder

375 g 375 g 100 g

BPW 2 /1:4 BPW/1:4 BPW/1:10 BPW/1:10 BPW/1:10 BPW/1:10

21 - 22 21 ± 1 21 ± 1 21 ± 1 21 ± 1 21 ± 1 18 ± 2 18 ± 2

41.5 ± 1 41.5 ± 1 41.5 ± 1 41.5 ± 1 41.5 ± 1 41.5 ± 1 41.5 ± 1 41.5 ± 1

BAM 4 MLG MLG BAM BAM BAM BAM BAM

Raw beef trim

Pasteurized liquid egg

Raw salmon

25 g 25 g 25 g

October 2018

Cheddar cheese Romaine lettuce

Stainless steel surface Polystyrene surface

4” x 4” surface 1” x 1” surface

100 mL BPW 10 mL BPW Enrichment Dilution mBPW 3 /1:10

Method Modification 1

Enrichment Time (h)

Enrichment Temp (°C)

Reference Method

Matrices

Sample size

Whole black peppercorns

25 g

22 ± 2

41.5 ± 1

BAM

Paprika powder

25 g

mBPW/1:10

22 ± 2

41.5 ± 1

BAM

August 2019

Cinnamon powder

25 g

mBPW/1:50

22 ± 2

41.5 ± 1

BAM

Honey mustard onion seasoning

375 g

mBPW/1:10

22 ± 2

41.5 ± 1

BAM

Ranch seasoning BAM 1 AOAC PTM Certificate No. 101801 , 2 Solus BPW (ISO)- Solus Buffered Peptone Water, ISO Formulation (with Solus Supplement), 3 Solus mBPW (ISO)- Solus Modified Buffered Peptone Water, ISO Formulation (with Solus Supplement), 4 MLG – USDA Microbiology Laboratory Guidebook; BAM – FDA Bacteriological Analytical Manual 375 g mBPW/1:10 22 ± 2 41.5 ± 1

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