Evaluation of the MC-Media Pad® Rapid Aerobic Count Device for the Enumeration of Total Aerobic Counts in a Variety of Foods: Collaborative Study, First Action Official MethodSM 2019.02

Abstract

The MC-Media Pad® Rapid Aerobic Count is a ready-to use culture device combining a test pad coated with medium and water absorption polymers that are designed for the rapid quantification of total aerobic bacteria in food products. The MC-Media Pad® RAC was compared to the U.S. Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) Microbiology Laboratory Guidebook (MLG) Chapter 3.02: Quantitative Analysis of Bacteria in Foods as Sanitary Indicators for raw ground pork and the Standard Methods for the Examination of Dairy Products (SMEDP) Chapter 6: Microbial Count Methods for yogurt drink. The candidate method was evaluated against the reference methods using a paired study design in a multi-collaborator study following the current AOAC Appendix J Guidelines. Three (3) target contamination levels (low, medium, and high) were evaluated. MC-Media Pad® RAC devices were enumerated after 24 and 48 hours of incubation. Plate counts obtained by both methods were log10-transformed and the difference of means (including 95% confidence intervals), repeatability SD, and reproducibility SD were determined for each contamination level. All 95% confidence intervals for mean difference fell easily within ±0.10, the performance requirement being ±0.5. The MC-Media Pad® RAC (for both 24 and 48 hours) and both reference methods for each contamination level were therefore shown equivalent with 97.5% confidence. The new method offers a convenient alternative to the reference methods for detection of Aerobic Plate Count in food products, yielding reliable and comparable results in 24 or 48 hours compared to 48 hours for the reference methods.