AOAC ERP MICRO AUGUST 2018

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

very little recovery benefit, if any, of the additional 24 h incubation. In all there were 11 matrices studied 359

with 9 different strains of spiked EB and 2 with natural contamination. In every evaluation the Peel 360

Plate EB method demonstrates equivalence to the reference methods at both the 24 h incubation and 361

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48 h incubation times using either a singlet or duplicate analysis.

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Table 8 are cereal data in which the prepared samples were also plated on Peel Plate EBHV, 5 mL

volume method. Cereal at a 1:10 dilution preparation is too thick and viscous to test in Peel Plate 364

method and therefore 1:50 dilution of cereal is prescribed. This means that 5 mL of the preparation 365

need to be tested instead of 1 mL to obtain a CFU/0.1g/plate result. With the Peel Plate EB method 366

reported in Tables 4,5,6 and 7, five plates were performed and the bacterial colonies on each plate 367

summed for a colonies/0.1g result. The Peel Plate HV plate is designed for 5 mL volume and therefore 368

just one plate and sample addition is a preferred option of users. The Peel Plate HV method was not 369

significantly different from the reference methods in these cereal evaluations. The recovery of bacteria 370

is improved with the HV method compared to the reference method and the Peel Plate EB 1 mL 371

method. This could reflect the fewer pipetting manipulations and faster time to pipet samples. Table 8 372

shows the statistical parameters of the EBHV singlet result at 24 h and the duplicate results at 48 h. 373

There is no significant improvement in the recovery or the confidence limits if a 24 h singlet results is 374

used or the 48 h duplicate result is used, both are statistically the same and equivalent to the reference 375

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methods.

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Collaborative Study The inclusivity/exclusivity and matrix studies demonstrated and satisfy validation body ERP Use Only

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requirements that the candidate method accurately enumerated Enterobacteriaceae in select foods and 381

environmental surfaces as claimed by the manufacturer, and that no difference in repeatability was 382

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