AOAC RI ERP Final Action Recommendations eBook
Dupont BAX Salmonella PTM Report Modification Approved 2012 / PTM Certification No. 081201 For Expert Review Panel Use Only Do Not Distribute
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an assumed concentration of 10 9 cfu/mL. Strains were serially diluted in additional BHI broth to levels
expected to produce fractional positive results based on previous studies.
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Table 1. Selected Matrices and Enrichment Methods Sample matrix Inoculation strain name and ID
Reference method enrichment media
BAX® System enrichment media Reference method
Ground Beef
S.Heidelberg ( DD13017 )
USDA MLG [4]
mTSB (TSB + 2 mg/L novobiocin)
BPW* / TT-Hajna & RVS
mTSB (TSB + 2 mg/L novobiocin) Health Canada [3]
BPW / TBG & RVS
Cream Cheese Dry Pet Food
S . Typhimurium (DD586) S . Tennessee (DD13062)
BAX® System MP media
U.S. FDA BAM [2]
LB* / FDA RV & TT
BPW / BHI broth
Health Canada [3]
BPW / TBG & RVS
Lactose broth / BHI broth
Health Canada [3]
BPW / TBG & RVS
185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201
* Reference method enrichment schemes also evaluated with the BAX® System test method.
For ground beef, a master sample was made at approximately 1 cfu per analytical portion. Ground
beef was divided into portions of reference method analytical size (25g) and each was inoculated with
4 X 10µL aliquots of an approximately 1 cfu / 40 µL suspension. Some portions were left un-spiked to
serve as negative controls. Spiked ground beef portions were re-combined on an aluminum foil coated
surface and hand massaged to homogenize. The master sample was held at 4±3°C for two to three
days to acclimate/stress the target cells. For the reference methods, analytical size portions (25 g)
were placed into sterile bags. For the BAX® System method, analytical size portions (25 g spiked
master sample and 350 g of unspiked product for each sample) were placed into sterile bags.
For cream cheese, a master sample was made at approximately 1 cfu per analytical portion.
AOAC INTERNATIONAL Cream cheese was divided into portions of analytical size (25 g) and each was inoculated with 4 X 10 µL aliquots of an approximately 1 cfu / 40 µL suspension. Some portions were left un-spiked to serve as negative controls. Spiked cream cheese portions were re-combined on an aluminum foil coated
surface and hand massaged to homogenize, then all test portions were held at 2-8°C for two to three
days to acclimate/stress the target cells. Analytical size portions (25 g) were removed and placed into
sterile stomacher bags.
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