227 / 596
13
method per matrix: 12 inoculated with a high level of
Listeria monocytogenes
, 12 inoculated
1
with a low level of
Listeria monocytogenes
, and 12 un-inoculated controls.
2
A background screen of the matrix indicated an absence of indigenous
Listeria monocytogenes
in
3
both matrices.Ten (10) replicate test portions (randomly sampled from 50% of the total packages
4
used in the analysis) were screened for the presence of
Listeria monocytogenes
. All test portions
5
produced negative results for the target analyte.
6
Results for the heat stress analysis of the inoculum for the deli turkey are presented in Table 2.
7
Table 2016.1A and 2016.1B summarize the inter-laboratory results for all foods tested, including
8
POD statistical analysis. As per criteria outlined in Appendix J of the AOAC Validation
9
Guidelines, fractional positive results were obtained.Detailed results for each laboratory are
10
presented in Tables 2016.2A and 2016.2B. For each matrix, the level of
Listeria monocytogenes
11
was determined by MPN on the day of initiation of analysis by the coordinating laboratory. MPN
12
results are presented in Tables 2016.2A and 2016.2B.The individual laboratory and sample
13
results are presented in Tables 1-2 of the Supplementary Materials. The APCresults for each
14
collaborating are presented in Table3 of the Supplementary Materials.
15
16
Deli Turkey (125 g Test Portions)
17
18
Deli turkeytest portions were inoculated at a low and high level and were analyzed for the
19
detection of
Listeria monocytogenes
. Un-inoculated controls were included in each analysis.
20
Laboratories 8 and 10 received test portions but were unable to conduct the analysis and
21
therefore no data was submitted. All other laboratories submitted data for both methods
22
evaluated. The MPN levels obtained for this matrix, with 95% confidence intervals, were 0.63
23
CFU/test portion (0.49,0.80) for the low inoculum level and 4.52 CFU/test portion (3.19, 6.42)
24
for the high inoculum level.
25
For the low inoculum level, 69 out of 132 test portions (POD
CP
of 0.52) were reported as
26
presumptive positive by the 3M MDA 2 –
Listeria monocytogenes
method with 66out of 132 test
27
portions (POD
CC
of 0.50) confirming positive. For samples that produced presumptive positive
28
results on the 3M MDA 2 –
Listeria monocytogenes
method, 66out of 132 samples confirmed
29
positive (POD
C
of 0.50). For test portions evaluated by the USDA/FSIS MLG reference method,
30
60 out of 132 test portions produced positive results. A dLPOD
C
value of 0.04 with 95%
31
confidence intervals of (-0.08, 0.17) was obtained between the candidate and reference method,
32
indicating no statistically significant difference between the two methods. A dLPOD
CP
value of
33
0.02 with 95% confidence intervals of (-0.10, 0.15) was obtained between presumptive and
34
confirmed results indicating no statistically significant difference between the presumptive and
35
confirmed results.
36
For the high inoculum level, 132 out of 132 test portions (POD
CP
of 1.00) were reported as
37
presumptive positive by the 3M MDA 2 –
Listeria monocytogenes
method with 132out of 132
38
test portions (POD
CC
of 1.00) confirming positive.For samples that produced presumptive
39
positive results on the 3M MDA 2 –
Listeria monocytogenes
method, 132out of 132 samples
40
confirmed positive (POD
C
of 1.00). For test portions evaluated by the USDA/FSISMLG
41
reference method, 132 out of 132 test portions produced positive results. A dLPOD
C
value of
42
AOAC Research Institute
Expert Review Panel Use Only
OMAMAN-30 A/ Collaborative Study Manuscript
OMA ERP June 2016
ERP Use Only