Microsoft Word - 3M Petrifilm REC Plate OMA Manuscript 09121

ERP Methods Book

84

For dairy matrices compared to the FDA BAM Chapter 4 reference method, an 11 g portion  1

was added to 99 mL of BPBD and blended for 2 min. Following homogenization, ten‐fold serial  2

dilutions were prepared in BPBD to obtain 1–100 CFU per plate. For comparison to the ISO  3

4832:2006 and ISO 16649‐2:2001 reference methods, a 10 g portion was added to 90 mL of PSS  4

and homogenized for 2 min. Following homogenization, ten‐fold serial dilutions were prepared  5

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in PSS to obtain 1–100 CFU per plate. 

For all other foods compared to the FDA BAM Chapter 4 reference method, a 50 g portion  7

was added to 450 mL of BPBD and blended for 2 min. Following homogenization, ten‐fold serial  8

dilutions were prepared in BPBD to obtain 1–100 CFU per plate. For comparison to the ISO  9

4832:2006 and ISO 16649‐2:2001 reference methods, a 10 g portion was added to 90 mL of PSS  10

and homogenized for 2 min. Following homogenization, ten‐fold serial dilutions were prepared  11

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in PSS to obtain 1–100 CFU per plate. 

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For stainless steel and sealed concrete (4” x 4” surface area) compared to the FDA BAM 

Chapter 4 reference method, after sampling each sponge was added to 25 mL of BPBD and  14

homogenized for 1 min. Following homogenization, 10 mL aliquots were serially diluted in 90  15

mL of BPBD to obtain 1–100 CFU per plate. For test portions compared to the ISO 4832:2006  16

and ISO 16649‐2:2001 reference methods, after sampling each sponge was added to 25 mL of  17

PSS and homogenized for 1 min. Following homogenization, 10 mL aliquots were serially diluted  18

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in of 90 mL PSS to obtain 1–100 CFU per plate. 

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The 3M Petrifilm Rapid E. coli /Coliform Count Plates were placed on a flat, level surface. The 

top film of the plate was lifted, and with the pipette perpendicular to the plate, a 1 mL aliquot  21

of each dilution was dispensed onto the center of the bottom film. The top film was rolled  22

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December 6, 2018