Micro December 2018
3M Petrifilm Rapid E. coli /Coliform Count Plate
ISO 4832:2006
95% CI g
Cont. level a
Matrix
Mean b
s r
RSD r
Mean
s r
RSD r
Mean diff. f
LCL h
UCL i
c
d
Ready- made- sandwiches
High
4.852
0.077
1.587
4.868
0.076
1.561
-0.016
-0.055
0.023
Low Med High Low Med High Low Med High Low Med High Low Med High
1.877 2.887 4.852 1.877 2.887 4.934 1.874 2.900 4.852 2.563 3.631 4.303 1.831 2.877 4.801
0.067 0.076 0.077 0.067 0.076 0.028 0.089 0.055 0.077 0.226 0.146 0.107 0.053 0.067 0.077
3.570 2.632 1.587 3.570 2.632 0.567 4.749 1.897 1.587 8.818 4.021 2.487 2.895 2.329 1.604
1.891 2.909 4.853 1.901 2.902 4.908 1.864 2.909 4.881 2.717 3.626 4.477 1.863 2.894 4.829
0.046 0.064 0.084 0.055 0.067 0.049 0.080 0.053 0.077 0.063 0.079 0.097 0.088 0.062 0.060
2.433 2.200 1.731 2.893 2.309 0.998 4.292 1.822 1.578 2.319 2.179 2.167 4.724 2.142 1.242
-0.013 -0.022 -0.001 -0.024 -0.015 0.025 0.010 -0.017 -0.029 -0.154 0.005 -0.174 -0.032 -0.017 -0.029
-0.076 -0.052 -0.021 -0.089 -0.032 -0.012 -0.043 -0.026 -0.084 -0.414 -0.113 -0.303 -0.154 -0.084 -0.071
0.050 0.008 0.018 0.042 0.001 0.063 0.063 -0.009 0.025 0.106 0.124 -0.044 0.090 0.049
Raw veg with dressing
Chicken feed
Soybean meal
Stainless steel
Sealed concrete
0.014 a All matrices are artificially contaminated. An uncontaminated level was not tested, as per ISO 16140-2, Microbiology of the food chain — Method validation — 1 Part 2: Protocol for the validation of alternative (proprietary) methods against a reference method. 2 b Mean of five replicate portions, plated in duplicate, after logarithmic transformation: Log 10 [CFU/g + (0.1)f]. 3 c Repeatability standard deviation. 4 d Relative standard deviation for repeatability. Reported as a percentage. 5 e ISO 4832:2006, Microbiology of food and animal feeding stuffs -- Horizontal methods for the enumeration of coliforms – Colony- count technique. 6 f Mean difference between the candidate and reference methods. 7 g Confidence interval based on paired statistical analysis. 8 h 95% Lower confidence limit for difference of means. 9 i 95% Upper confidence limit for difference of means.
10 11
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