AOAC ERP MICRO AUGUST 2018

OMAMAN-44 A: Collaborative Study Manuscript Expert Review Panel Use Only August 2018

552

Assay Temperature showed no significant difference by t-test or paired log-T test confidence levels

>0.5. A shorter assay time did not show a significant difference by t-test and there is no significant 553

difference between the shorter 22 and longer 50 hour incubation times. Pipet volume did show a 554

significant difference by t-test as would be expected with a low bias of the 900µL compared to the 1100 555

µL dispense; however the low bias using the mean log difference and confidence limits >0.5 log 556

557

specification is not considered significantly different.

558

The effect of moisture loss from an exposed unsealed test strip and the effect of moisture loss on a

test exposed for 15 minutes in a laminar flow hood were determined. In control experiments with 559

sealed strips, there is less than a 1% loss of weight, while there was a 10-15% weight loss after 15 560

minutes open air exposure that would simulate an environmental sample of a food plant. Moisture loss 561

studies were performed with 3 lots of EB tests in 3 sets (n=10 each) with Butterfields buffer fortified 562

with either Hafnia alvei ATCC 51815 , Pantoea agglomerans ATCC 27155 or Enterobacter aerogenes 563

ATCC 13048 . Plates had diluted samples added and were sealed (control) and left exposed in 32°C 564

incubator for 15 minutes to achieve volume loss of 10- 15%. Average and standard deviations were 565

calculated and reported in Table 12. Overall there were not a significant differences (±2SD) in the 566

bacterial recovery on the control compared to the air exposed plates on any of the 3 lots of tests 567

568

evaluated.

569

Conclusion

570

571 Pre-collaborative study demonstrate that Peel Plate for Enterobacteriaceae Bacteria (EB) method ERP Use Only incubated at 37 ± 1°C for 24 up to 48 h, without a confirmatory step, selectively detect EB and exclude 573 572

non-EB. Matrix studies of heat processed milk and dairy products, infant formula and cereals, and 574

environmental surfaces, and chicken rinse samples, were not significantly different from the standard 575

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