Validation of the FSTestTM Aerobic Count Plates Method for Enumeration of Aerobic Bacteria in a Variety of Matrixes and Stainless Steel Environmental Surface: AOAC Performance Tested MethodSM 112301.

BACKGROUND: The FSTestTM Aerobic Count (AC) Plates are ready-to-use culture mediums containing nutrients, a cold-water-soluble gelling agent and a chromogenic indicator.

OBJECTIVE: The objective of this study was to validate the FSTest AC plate method for the AOAC Performance Tested MethodsSM (PTM) certification for a variety of foods and stainless steel.

METHODS: The performance of the FSTest AC plates were compared to the appropriate reference method, for the detection of total aerobic bacterial in a variety of foods matrixes (raw ground beef, raw ground pork, cooked ham, raw chicken breast, raw shrimp, frozen tuna, shredded bagged lettuce, cherry tomato, pasteurized liquid milk, nonfat milk powder) and stainless steel surface. The robustness, consistency, and stability studies of the FSTest AC plate were also conducted.

RESULTS: The results of the matrix study showed the standard deviation of repeatability (sr) was similar in both the FSTest AC plate method and the reference method. The 90% confidence interval of the difference between means between the two methods was found to fall within -0.5 to 0.5 log10 for all matrixes at all levels in the method developer and independent laboratory studies. The data in the report also supports that the FSTest AC plate method is robust, manufactured in a consistent manner and can be stable for 18 months at 4-10 °C.

CONCLUSION: The FSTest AC method is validated to be equivalent to the appropriate reference methods for the enumeration of aerobic bacteria in a variety of food matrixes and stainless steel surface at 36 ± 1 °C, and 32 ± 1 °C (for dairy matrixes) in 24 ± 1 h.

HIGHLIGHTS: The FSTest AC plate method offers the advantage of saving labor, space and time, as results are available within 24 h for all tested matrixes.