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Bird et al.: J ournal of AOAC International Vol. 98, No. 3, 2015 773
statistically. One laboratory in the FDA BAM/ISO 21527 low
contamination level was identified as an outlier as defined by the
Cochran’s tests for outliers. However, no evidence of physical
cause or suspicion of cause was noted and it was determined
that they would be included in the statistical analysis.
There were no statistically significant differences at the 5%
level in log transformed means between the 3M Petrifilm RYM
Count Plate method and FDABAM/ISO 21257 methods, at any
of the three contamination levels.
3M RYM Count Plate incubated at 25°C and enumerated
at 60 h.—The mean log10 counts of the 3M Petrifilm RYM
Count Plate and FDA BAM/ISO 21527 results were compared
statistically. One laboratory in the FDA BAM/ISO 21527 low
contamination level was identified as an outlier as defined by the
Cochran’s tests for outliers. However, no evidence of physical
cause or suspicion of cause was noted and it was determined
that they would be included in the statistical analysis.
There were no statistically significant differences at the 5%
level in log transformed means between the 3M Petrifilm RYM
Count Plate method and FDABAM/ISO 21257 methods, at any
of the three contamination levels.
3M RYM Count Plate incubated at 28°C and enumerated
at 48 h.—The mean log10 counts of the 3M Petrifilm RYM
Count Plate and FDA BAM/ISO 21527 results were compared
statistically. One laboratory in the FDA BAM/ISO 21527 low
contamination level was identified as an outlier as defined by the
Cochran’s tests for outliers. However, no evidence of physical
cause or suspicion of cause was noted and it was determined
that they would be included in the statistical analysis.
There were no statistically significant differences at the 5%
level in log transformed means between the 3M Petrifilm RYM
Count Plate method and FDABAM/ISO 21257 methods, at any
of the three contamination levels.
3M RYM Count Plate incubated at 28°C and enumerated
at 60 h.—The mean log10 counts of the 3M Petrifilm RYM
Count Plate and FDA BAM/ISO 21527 results were compared
statistically. One laboratory in the FDA BAM/ISO 21527 low
contamination level was identified as an outlier as defined by the
Cochran’s tests for outliers. However, no evidence of physical
cause or suspicion of cause was noted and it was determined
that they would be included in the statistical analysis.
There were no statistically significant differences
determined between the 3M Petrifilm RYM Count Plate and
FDABAM/ISO 21527 methods at the 95% level or between the
differences of means at all three contamination levels.
Raw Almonds
Raw almond test portions were inoculated at a low, medium
and high contamination level and were analyzed (Tables 6–9)
for the enumeration of yeast and mold. Uninoculated controls
were included in each analysis. Fifteen laboratories participated
in the analysis of this matrix.
3M RYM Count Plate incubated at 25°C and enumerated
at 48 h.—The mean log10 counts of the 3M Petrifilm RYM
Count Plate and FDA BAM/ISO 21527 results were compared
statistically. One laboratory was identified in the 3M Petrifilm
RYM Count Plate medium contamination results as an outlier
by the Cochran’s test for outliers, one laboratory was identified
in the FDA BAM/ISO 21527 high contamination level as an
outlier by the Single Grubbs’ test, and two laboratories in the
3M Petrifilm RYM Count Plate high contamination level were
identified as an outlier by the double Grubbs’ test for outliers.
However, no evidence of physical cause or suspicion of cause
was noted and it was determined that they would be included in
the statistical analysis.
There were no statistically significant differences at the 5%
level in log transformed means between the 3M Petrifilm RYM
Count Plate method and FDABAM/ISO 21257 methods, at any
of the three contamination levels.
3M RYM Count Plate incubated at 25°C and enumerated at
60 h.—The mean log10counts of the 3MPetrifilmRYMCount Plate
and FDA BAM/ISO 21527 results were compared statistically.
One laboratory was identified in the FDA BAM/ISO 21527
high contamination level as an outlier by the Single Grubbs’ test
and two laboratories in the 3M Petrifilm RYM Count Plate high
contamination level were identified as an outlier by the double
Grubbs’test for outliers. However, no evidence of physical cause or
suspicion of cause was noted and it was determined that they would
be included in the statistical analysis.
There were no statistically significant differences determined
between the 3M Petrifilm RYM Count Plate method and
FDABAM/ISO 21527 methods at the 95% level or between the
differences of means at all three contamination levels.
3M RYM Count Plate incubated at 28°C and enumerated
at 48 h.—The mean log10 counts of the 3M Petrifilm
RYM Count Plate and FDA BAM/ISO 21527 results were
compared statistically. One laboratory was identified in the
FDABAM/ISO 21527 high contamination level as an outlier by
the Single Grubbs’ test and two laboratories in the 3M Petrifilm
RYM Count Plate high contamination level were identified as
an outlier by the double Grubbs’ test for outliers. However, no
evidence of physical cause or suspicion of cause was noted and
it was determined that they would be included in the statistical
analysis.
There were no statistically significant differences at the 5%
level in log transformed means between the 3M Petrifilm RYM
Count Plate and FDA BAM/ISO 21257 methods, at any of the
three contamination levels.
3M RYM Count Plate incubated at 28°C and enumerated
at 60 h.—The mean log10 counts of the 3M Petrifilm
RYM Count Plate and FDA BAM/ISO 21527 results were
compared statistically. One laboratory was identified in the
FDABAM/ISO 21527 high contamination level as an outlier by
the Single Grubbs’ test and two laboratories in the 3M Petrifilm
RYM Count Plate high contamination level were identified as
an outlier by the double Grubbs’ test for outliers. However, no
evidence of physical cause or suspicion of cause was noted and
it was determined that they would be included in the statistical
analysis.
There were no statistically significant differences at the 5%
level in log transformed means between the 3M Petrifilm RYM
Count Plate method and FDABAM/ISO 21257 methods, at any
of the three contamination levels.
Discussion
No negative feedback was reported to the study directors from
the collaborating laboratories in regards to the performance
of the 3M Petrifilm RYM Count Plate. A few laboratories
indicated difficulty in spreading the test portion liquid aliquot
over the entire surface of the plate before the sample began to