ERP Micro December 2019

1 2 3 4 5 6 7 8 9

*

ATCC = American Type Culture Collection

3.2 Matrix Study: Foods

Formatted: Outline numbered + Level: 2 + Numbering Style: 1, 2, 3, … + Start at: 1 + Alignment: Left + Aligned at: 0.5" + Indent at: 0.8"

The study will include five replicate test portions of uninoculated matrix, 20 replicate test portions at a low level to yield fractionally positive results, and five replicate test portions at a high level to yield consistently positive results ( Table 2 ). Fractionally positive results, those in which at least one of the methods (candidate or reference) yields 5-15 positive results out of 20 replicates examined for the low level of inoculation, are required for each matrix tested. Results in which the candidate method is above the fractional range and the reference method is below the fractional range are also considered acceptable. NOTE: replicates are to be taken from a singularly inoculated lot of material . Naturally contaminated matrix can be used if available . If naturally contaminated matrix is used, two lots must be tested. Fractionally positive results are

10 11 12 13 14 15 16 17 18 19 20

required by at least one of the methods for at least one of the lots.

Table 2. Food Preparation

Inoculation Level per Organism 0 cfu/375g

Inoculation Organisms

Test Portion

Matrix

Replicates

Method

5

375g 375g 375g 325g 325g 325g 375g 375g 375g 325g 325g 325g

Raw beef trim

E. coli O157:NM

GDS O157

0.2–2 cfu/375g 2–10 cfu/375g

20

5 5

0 cfu / 3 25g

Raw beef trim

MLG 5.095C.00

E. coli O157:NM

0.2–2 cfu/ 3 25g 2–10 cfu/ 3 25g

20

5 5

0 cfu/375g

Frozen finely trimmed beef Frozen finely trimmed beef

0.2–2 cfu/375g 2–10 cfu/375g

20

E. coli O157:H7

GDS O157

5 5

0 cfu / 3 25g

MLG 5.095C.00

0.2–2 cfu/ 3 25g 2–10 cfu/ 3 25g 0 cfu / 375g25g

20

E. coli O157:H7

5 5

E. coli O157:H7

375g25g

GDS O157

8