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B

ird

et al

.:

J

ournal of

AOAC I

nternational

V

ol

.

98, N

o

. 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 log

10

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 log

10

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 log

10

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 log

10

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 log

10

counts 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 log

10

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 log

10

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