18 / 199
B
ird
et al
.:
J
ournal of
aoaC i
nternational
V
ol
.
99, n
o
.
4, 2016
995
Creamy Peanut Butter (25 g Test Portions)
Creamy peanut butter test portions were inoculated at a
low and high inoculum level and were analyzed (Table 4)
for the detection of
Salmonella
spp. Uninoculated controls
were included in each analysis. Laboratory 16 did not
participate in the evaluation of this matrix. Laboratories 5
and 11 received test portions but were unable to conduct the
analysis and therefore no data were submitted. Laboratory
7 reported deviations from the testing protocol in the heat
lysis step (incorrect temperature used). Laboratory 3 reported
contamination of its uninoculated control samples with the
inoculating strain. Due to this issue, the data submitted from
Laboratories 3 and 7 were not used in the statistical analysis.
All other laboratories submitted complete data for each
method. The MPN levels obtained for this test portion were
0.70 CFU/test portion (95% confidence interval, 0.55–0.89)
for the low level and 5.35 CFU/test portion (95% confidence
interval, 3.46–8.24) for the high level.
For the low inoculum level, 78 of 132 test portions (POD
CP
of 0.59) were reported as presumptive positive by the 3M MDA
2 –
Salmonella
method, with 76 test portions (POD
CC
of 0.58)
confirming positive. For samples that produced presumptive
positive results on the 3M MDA 2 –
Salmonella
method,
76 samples confirmed positive (POD
C
of 0.58). For test portions
evaluated by the FDA BAM reference method, 68 of 132 test
portions produced positive results. A dLPOD
C
value of 0.06
(95% confidence interval, −0.06 to 0.18) was obtained between
the candidate and reference method, indicating no statistically
significant difference between the two methods. A dLPOD
CP
value of 0.02 (95% confidence interval, −0.11 to 0.14) was
obtained between presumptive and confirmed results, indicating
no statistically significant difference between the presumptive
and confirmed results.
For the high inoculum level, 132 of 132 test portions (POD
CP
of 1.00) were reported as presumptive positive by the 3M MDA
2 –
Salmonella
method, with 132 test portions (POD
CC
of 1.00)
confirming positive. For samples that produced presumptive
positive results on the 3M MDA 2 –
Salmonella
method, 132
samples confirmed positive (POD
C
of 1.00). For test portions
evaluated by the FDA BAM reference method, 132 of 132 test
portions produced positive results. A dLPOD
C
value of 0.00
(95% confidence interval, −0.03 to 0.03) was obtained between
the candidate and reference method, indicating no statistically
significant difference between the two methods. A dLPOD
CP
value of 0.00 (95% confidence interval, −0.03 to 0.03) was
obtained between presumptive and confirmed results, indicating
no significant difference found between the presumptive and
confirmed results.
For the uninoculated controls, 2 of 132 samples (POD
CP
of
0.01) produced a presumptive positive result by the 3M MDA
2 –
Salmonella
method, with 0 test portions (POD
CC
of 0.00)
confirming positive. For samples that produced presumptive
positive results on the 3M MDA 2 –
Salmonella
method,
0 samples confirmed positive (POD
C
of 0.00). For test portions
evaluated by the FDA BAM reference method, 0 of 132 test
portions produced positive results. A dLPOD
C
value of 0.00
(95% confidence interval, −0.03 to 0.03) was obtained between
the candidate and reference method, indicating no statistical
significant difference between the two methods. A dLPOD
CP
value of 0.01 (95% confidence interval, −0.01 to 0.05) was
obtained between presumptive and confirmed results, indicating
no significant difference between the presumptive and confirmed
results. Detailed results of the POD statistical analysis are
presented in Table
2016.01D
and Figures 3 and 4.
Figure 2. dPOD values of candidate method versus reference method for 325 g raw ground beef (73%).