AOAC ERP MICRO AUGUST 2018

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

Pre-collaborative and Collaborative Report Peel Plate EB

Table 5. Continued - Peel Plate-EB Method (Duplicate count) for Enterobacteriaceae at 24 hours vs ISO Methods 21528-1 and 2.

Fortified micro- organisms ATCC No. (% injury) Serratia marcescens ATCC 13880 (48% heat stress injury) Klebsiella oxytoca ATCC 700324 (42% heat stress injury) Enterobacter aerogenes ATCC 13048 (20% heat stress injury)

Candidate Method

95% CI e

Reference Method

Mean diff. d

Cont. level

r 2 h

Matrix

Mean a

Mean a

s r

RSD r

s r

RSD r

LCL f

UCL g

b

c

b

c

None

<0.1 1.539 2.868 5.533 <0.1 1.488 2.911 5.464 <0.1 1.547 4.931 5.486 1.736 2.399 3.437 <0.1 1.422 3.491 4.451

na

na 15

<0.1 1.664 3.075 5.458 <0.1 1.551 3.042 5.560 <0.1 1.551 5.042 5.560 1.942 2.430 3.480 <0.1 1.627 3.559 4.564

na

na

na

na

na

Unsalted butter

0 3 4

0.998

low mid high low mid high low mid high low mid high low mid high

0.236 0.121 0.095 0.272 0.058 0.122 0.303 0.048 0.134 0.365 0.139 0.332 0.409 0.071 0.088 na na na

0.000 0.085 0.196 0.154 0.037 0.197 0.154 0.037 0.197 0.440 0.286 0.484 0.271 0.139 0.058 na na na

-0.125 -0.207 0.075 -0.063 -0.131 -0.096 -0.004 -0.111 -0.074 -0.206 -0.031 -0.043 -0.205 -0.068 -0.113 na na na

-0.417 -0.360 -0.112 -0.297 -0.219 -0.346 -0.242 -0.190 -0.314 -0.378 -0.322 -0.310 -0.489 -0.182 -0.266 na na na

0.268 -0.054 0.262 0.170 -0.044 0.153 0.233 -0.033 0.166 -0.035 0.260 0.224 0.079 0.046 0.041 na na na

4 2

None

na 18

na 10

Vanilla ice cream

0.999

2 2

1 4

None

na 20

na 10

Soy infant formula Chicken Rinse in BPW

0.997

1 2

1 4

21

23 12 14 na 17

Natural Contamination

6

0.993

10 na 29

None

Citrobacter freundii 8090 (Lyophilized)

Rice infant cereal

0.999

2 2

4 1

a Mean of 5 replicate portions, plated in duplicate, after logarithmic transformation: Log 10 [CFU/g + (0.1)f]. b Repeatability standard deviation. c Relative standard deviation for repeatability. d Mean difference between the candidate and reference methods. e Confidence interval. f 95% Lower confidence limit for difference of means.

g 95% Upper confidence limit for difference of means ERP Use Only i na- not applicable j Independent lab performed

h Square of correlation coefficient.

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