AOAC ERP MICRO AUGUST 2018

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

Peel Plate TM EB ( Enterobacteriaceae Bacteria )

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AOAC-OMA/MicroVal Harmonized Validation

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AOAC Official Method 2018.XX

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Enumeration of Enterobacteriaceae in Select Foods and Environmental Surfaces

Peel Plate EB First Action 2018

Abstract

Peel Plate TM Enterobacteriaceae Bacteria (EB) is a dried selective media on a 47 mm plastic plate that on 10

simple rehydration and incubation for 24 up to 48 h at 37 ± 1°C produces colored colonies from enzyme 11

substrates. The method was Official Method of Analysis validated for quantification of EB compared to 12

reference methods, ISO 21528-Parts 1 & 2:2017. Matrices compared were whole milk, dried skim 13

powdered milk, vanilla ice cream, butter, infant formulas (soy and dairy based) and infant cereals with 14

and without probiotics. Surfaces supported with data are environmental sponge of stainless steel, and 15

poultry carcass rinse with two different peptone buffers. In inclusivity study the method detected 50 of 16

50 different EB strains; and in exclusivity study 30 of 30 different non-EB strains were not detected. In 17

matrix studies the claimed foods, either naturally contaminated or spiked at 3 levels, were paired 18

analysis tested by reference and Peel Plate EB methods. Log transformed data were evaluated and 19

demonstrated that the alternative and reference methods are not statistically different, defined as 20

mean log difference confidence intervals greater than |0.5 log|. International collaborative study with 21 ERP Use Only dried infant formula spiked with Cronobacter sakazakii at log 1.05, 2.31, and 3.21 levels, produced 22 method differences -0.16, 0.15 and 0.18 with repeatabilities r = 0.33, 0.20 and 0.12 and 23 reproducibilities R =0.45, 0.26 and 0.18. Based on these evaluations the alternative method is 24 considered equivalent to the reference methods at both the 24 and 48 hour incubation periods at 37C ± 25

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1°C.

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