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February 20, 2013
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Raw Ground Beef
1
For raw ground beef test portions, there were 13 confirmed positives the 3M Petrifilm SALX method at all
2
four time points and 13 confirmed positives for the USDA/FSIS-MLG method. All un-inoculated control
3
samples were negative by both methods. A χ
2
value of 0.0 was obtained between the reference and
4
candidate method using both the traditional and alternative confirmation procedures, indicating no
5
significant difference between the candidate and reference methods at any of the four time points.
6
7
For the low level inoculum, a dPOD
C
value of 0.00 with 95% confidence intervals of (-0.28, 0.28) was
8
obtained between the reference and candidate method samples confirmed using either the traditional or
9
alternative confirmation procedures at all four time points. The confidence intervals obtained for dPOD
C
10
indicated no significant difference between the two methods. A dPOD
CP
value of 0.00 with 95% confidence
11
intervals of (-0.28, 0.28) was obtained between presumptive and confirmed results using either
12
confirmation procedure for all four time points. The confidence intervals obtained for dPOD
CP
indicated no
13
significant difference between the presumptive and confirmed results at all four time points.
14
15
16
17
Raw Ground Pork
18
For raw ground pork test portions, there were 9 confirmed positives by the 3M Petrifilm SALX System at all
19
four time points and 9 confirmed positives by the USDA/FSIS-MLG method. All un-inoculated control
20
samples were negative by both methods. A χ
2
value of 0.0 was obtained between the reference and
21
candidate method samples using both the traditional and alternative confirmation procedures, indicating
22
no significant difference between the candidate and reference methods at any of the four time points.
23
24
For the low level inoculum, a dPOD
C
value of 0.00 with 95% confidence intervals of (-0.28, 0.28) was
25
obtained between the reference method and candidate method samples confirmed using either the
26
traditional or alternative confirmation procedure at all four time points. The confidence intervals obtained
27
for dPOD
C
indicated no significant difference between the two methods. A dPOD
CP
value of 0.00 with 95%
28
confidence intervals of (-0.28, 0.28) was obtained between presumptive and confirmed results using either
29
the traditional or alternative confirmation procedure for all four time points. The confidence intervals
30
obtained for dPOD
CP
indicated no significant difference between the presumptive and confirmed results at
31
all four time points.
32
33
Low Microbial Foods
34
Pasteurized Liquid Whole Eggs
35
For pasteurized liquid whole egg test portions, there were 6 confirmed positives by the 3M Petrifilm SALX
36
method at both time points and 4 confirmed positives by the USDA/FSIS-MLG method. All un-inoculated
37
control samples were negative for both methods. A χ
2
value of 0.98 was obtained between the USDA/FSIS-
38
MLG and candidate method using both traditional and alternative confirmation procedures, indicating no
39
significant difference between the candidate and reference method at any of the time points.
40
41
For the low level inoculum, a dPOD
C
value of 0.10 with 95% confidence intervals of (-0.17, 0.35) was
42
obtained between the USDA/FSIS-MLG method and the candidate method samples confirmed using either
43
the traditional or alternative confirmation procedure at both the 18 hour and 24 hour primary enrichment
44
time points. A dPOD
C
value of 0.05 with 95% confidence intervals of (-0.22, 0.31) was obtained between the
45
ISO 6579 method and the candidate method samples confirmed using either the traditional or alternative
46
confirmation procedure at both the 18 hour and 24 hour primary enrichment time points. The confidence
47