Purpose: The goal of this study is to compare the newly developed simplified methods, Charm Peel Plate EC HV (total coliform) and Peel Plate AC (aerobic count), to the NCIMS/FDA reference methods according to NCIMS laboratory committee procedures.
Methods: Gallon milk containers were tested in accordance with NCIMS/ FDA form 2400i Pasteurized Milk Containers using the 100 ml nutrient broth rinse method. The containers were divided into six (6) groups of five (5) containers each. Five (5) groups were inoculated with P. aeruginosa and K. pneumonia and/or E. coli at various levels. After broth addition and agitation, each container was plated using methods for coliform (Peel Plate EC HV, AOAC 996.02 and Violet Red Bile Agar confirmed with BGLB broth) and methods for aerobic plate (Peel Plate AC, AOAC 986.33 and Standard Plate Count Agar). Coliform tests were incubated at 32 ± 2°C for 24 ± 2 h and aerobic bacteria 32 ± 2°C tests 48 ± 3 h.
Results: In the method comparisons, results were evaluated for repeatability (Sr) and by paired-t-test for statistical difference using > 0.5 log. The Peel Plate EC HV and Peel Plate AC results were not significantly different, less than 0.2 log difference at each concentration, from the NCIMS/FDA reference pour plate and film methods for both coliform count and aerobic plate count.
Significance: The comparative analyses with Peel Plate AC and Peel Plate EC HVS show that these methods are at least equivalent to NCIMS/FDA approved reference methods and meets NCIMS acceptance criteria for single service container and closure testing according to Appendix J of the PMO.