Table 2014.05A.

Interlaboratory study results of 3M Petrifilm RYM versus FDA-BAM and ISO 21527 methods for frozen raw ground beef patties

		3M Petrifilm RYM method				BAM/ISO 21527 methodsa
Matrix	Lot	n b	Meanc	sr	sR	n	Mean	sr	sR	P-valued	Difference of means	Reverse transformed mean differencee
Frozen raw ground beef patties
25°C, 48 h	Control	11(0)	<1.00	—f	—	11(0)	<1.00	—	—	—	—	—
	Low	11(0)	2.12	0.41	0.41	11(1)	2.07	0.36	0.38	0.5323	0.05	14.34
	Medium	11(0)	3.52	0.10	0.10	11(0)	3.47	0.09	0.11	0.1637	0.05	360.10
	High	11(0)	4.65	0.13	0.14	11(0)	4.59	0.10	0.14	0.2266	0.06	5763.84
25°C, 60 h	Control	11(0)	<1.00	—	—	11(0)	<1.00	—	—	—	—	—
	Low	11(0)	2.14	0.36g	0.37	11(1)	2.07	0.36	0.38	0.3773	0.07	20.55
	Medium	11(0)	3.52	0.10	0.10	11(0)	3.47	0.09	0.11	0.1573	0.05	360.10
	High	11(0)	4.65	0.14	0.15	11(0)	4.59	0.10	0.14	0.1750	0.06	5763.84
28°C, 48 h	Control	11(0)	<1.00	—	—	11(0)	<1.00	—	—	—	—	—
	Low	11(0)	2.17	0.29g	0.30	11(1)	2.07	0.36	0.38	0.1391	0.10	30.42
	Medium	11(0)	3.53	0.10	0.10	11(0)	3.47	0.09	0.11	0.0824	0.06	437.23
	High	11(0)	4.67	0.08g	0.11	11(0)	4.59	0.10	0.14	0.0966	0.08	7869.00
28°C, 60 h	Control	11(0)	<1.00	—	—	11(0)	<1.00	—	—	—	—	—
	Low	11(0)	2.16	0.29g	0.29	11(1)	2.07	0.36	0.38	0.1843	0.09	27.05
	Medium	11(0)	3.53	0.09	0.10	11(0)	3.47	0.09	0.11	0.1095	0.06	437.23
	High	11(0)	4.67	0.08g	0.11	11(0)	4.59	0.10	0.14	0.1088	0.08	7869.00

^aSamples were analyzed by harmonized FDA-BAM Ch. 18 and ISO 21527 methods using 0.1% peptone water as the sample diluent.

^b n = Number of laboratories that reported complete results. Outliers are in parentheses.

^cLog₁₀ yeast and mold cfu/g.

^dSignificant difference (P < 0.05).

^eResults presented as cfu/g.

^fNot applicable. 

^gResults indicate that the candidate method is more repeatable than the reference methods. s_r = Repeatability standard deviation; s_R = reproducibility standard deviation.