Total Collaborative Study Protocol_Solus One Salmonella v1 1
considered acceptable.
For the matrix study evaluation of the candidate Solus One Salmonella method, a Salmonella Agona
ATCC 51957 (for raw beef trim matrix), a Salmonella Enteritidis ATCC 13076 (for pasteurized liquid egg
matrix), a Salmonella Virchow ATCC 51955 (for raw salmon fillet matrix), a Salmonella Heidelberg ATCC
8326 (for shredded cheddar cheese matrix), a Salmonella Muenchen ATCC BAA‐1594 (for bagged
Romaine lettuce matrix), a Salmonella Senftenberg ATCC 43845 (for non‐fat dry milk powder matrix), a
Salmonella Typhimurium ATCC 14028 (for stainless steel environmental surface matrix) and Salmonella
Montevideo ATCC 8387 (for plastic environmental surface matrix) inoculums were cultured by
transferring a single colony from trypticase soy agar with 5% sheep blood (SBA) into BHI broth for 24 ± 2
h at 35 ± 2°C to obtain stationary phase cell densities. The Salmonella starter cultures were
subsequently diluted in BHI broth, added to the respective matrixes and subsequently mixed. At these
low and high inoculum levels, fractional positives or consistently positive results at the time of sampling
were anticipated.
Where co‐inoculation was required, a Citrobacter freundii ATCC 8090 strain was cultured in BHI
broth for 22 ± 2 h at 35 ± 1°C and diluted to ten times the level of the Salmonella strain (890–3700
CFU/test area).
100 g pasteurized liquid egg and 375 g raw beef trim or NFDM test portions were prepared by
mixing together 25 g of inoculated test product with 75 g or 350 g of un‐inoculated test product
respectively.
The level of Salmonella in the low and high level inoculum for both 25 g and 100 g test portions
were determined by Most Probable Number (MPN) on the day of analysis. Each test portion was
enriched with the respective reference method enrichment (FDA/BAM Ch. 5 or MLG 4.09) and analyzed
by the reference method procedure. The number of positives from the 3 test levels were used to
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