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Table 3. Sample Analysis with Re-growth
Sample Type
Test from Primary
Enrichment
Test from
Re-growth
Re-growth
Required
Meat and Seafood
Raw ground beef with soy
Yes
No
No
Beef trim
Yes
No
No
Frankfurters
Yes
No
No
Shrimp
Yes
No
No
Poultry and Eggs
Ground turkey
Yes
No
No
Chicken wings
Yes
No
No
Dried eggs
Yes
Yes
No
Shell eggs
Yes
Yes
No
Produce
Frozen peas
Yes
Yes
No
Orange juice
No
Yes
Yes
Dairy Products
Nonfat dry milk
No
Yes
Yes
Ice cream
Yes
Yes
No
Environmentals
Ceramic tile
Yes
Yes
No
Plastic
Yes
Yes
No
Miscellaneous
Peanut butter
Yes
Yes
Yes
Cocoa
Yes*
Yes
No*
White pepper
Yes
Yes
No
Infant formula
Yes
Yes
No
* Cocoa samples tested from the primary enrichment were diluted 1:50 in BHI broth before processing.
2
Statistical Analysis
3
Data analysis was performed using each of the metrics below according to the format described in the
4
AOAC International Methods Committee Guidelines for Validation of Microbiological Methods for Food
5
and Environmental Surfaces and using the Least Cost Formulations, Ltd., AOAC Binary Data
6
Interlaboratory Study Workbook [6].
7
For the purposes of this evaluation, the probability of detection (POD) was defined as the number of
8
positive outcomes divided by the total number of trials. POD was estimated with a 95% confidence
9
interval for each of the following levels:
10
•
the candidate presumptive results (POD
CP
),
11
•
the candidate confirmatory results (POD
CC
),
12
•
the candidate method results based on the presumptive and confirmatory results (POD
C
)
13
•
the reference method results (POD
R
).
14
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