Purpose: This study was conducted to evaluate the comparative performance of 3 different dehydrated film media and reference methodology as described in FDA/BAM and ISO 21527:2008 (parts 1 and 2).
Methods: The method comparison was conducted using a variety of naturally contaminated food matrices (n = 65) with the dehydrated film methods and the reference method (FDA/BAM and ISO21527:2008, parts A and B). Each food sample was serially diluted in 0.1% peptone water. The dehydrated film media were hydrated with 1ml of the sample and 100 micro-liters were spread plated on DRBC or DG-18 media in duplicate.
Results: Statistical comparisons between the various dehydrated film methods at the prescribed readout times and the reference DRBC and DG-18 at 5 days demonstrated significant differences in P values (< 0.05) depending on the method. Additional qualitative differences in the appearance and handling of the various dehydrated film media were also observed.
Significance: Rapid test results are increasingly becoming more important for food processors. Developing tests with faster time to results without sacrificing performance is the ultimate goal. As newer technologies providing alternate methods become readily available, understanding the performance, recovery and handling across the various methods provides food microbiology laboratories with valuable information that will help informed decision making towards the method of choice.