AOAC ERP MICRO AUGUST 2018

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

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Peel Plate® EB Method. All matrixes were diluted according to the AOAC protocol as described

previously in “Method Procedure”. After dilution, all test portions were plated following the Peel Plate® 336

EB method or in the case of cereal also the Peel Plate EBHV® (high volume 5 mL) method. 337

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Statistical analysis was conducted for each contamination level for each matrix evaluated

comparing the Peel Plate EB method to the ISO reference method (1, 2, 3, 4). Logarithmic 339

transformations of the counts (CFU/g) were performed, and the difference of means, with 95% 340

confidence intervals, between the alternative method and the reference method was determined for 341

each contamination level. Mean difference and confidence intervals were calculated using the 342

Independent Laboratory Study Workbook for Paired Method Analysis for Micro Testing (ver. 1.0) 343

supplied by the AOAC Research Institute (1). A mean difference between methods of <0.5 log 10 with a 344

95% confidence interval (CI) containing values between (-0.5, 0.5) was used as guidance to determine 345

statistically significant differences between two methods being compared. The repeatability (s r ) of the 346

Charm Peel Plate® EB and ISO reference methods were determined for each matrix. 347

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Matrix Study Results and Discussion : Tables 4, 5, 6 and 7 are summary Tables of evaluated matrices,

showing the spiked bacteria or natural contamination levels evaluated, and the resulting mean log 349

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from 5 paired results between the Peel Plate EB and reference methods. The tables

averages and s r

include mean log differences associated between the alternative and reference with the confidence 351

limits and correlation coefficient, r 2 , of the mean log linear regression curve. Table 4 compares a singlet 352

24 h Peel Plate EB result to the reference method duplicate result at 48 h. Table 5 compares a duplicate 353 ERP Use Only analysis of the 24 h result to reference. Tables 6 and 7 present the 48 h Peel Plate EB singlet and 354 duplicate test result to the reference. In all analyses the confidence limits of the alternative method log 355 differences with reference are within 0.5 log and indicate no significant differences with the reference 356

methods. Duplicate analysis compared to singlet analysis produces very little change to the mean 357

differences or the confidence limits. The 24 h analysis statistics are comparable to 48 h analysis showing 358

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