The effectiveness of the firefly rapid method in determining sanitation procedures at a Tuna processing plant

Abstract

The first steps in the implementation of food safety regulations are often the sanitation procedures. The main objective of this study was to determine the level of surface contamination at different points in a tuna processing plant using microbiological evaluation (Log CFU/mL) and then correlating them to the relative light units (RLU) values from the firefly rapid method. The second objective of this study was to assess and compare how changing the sampling surface area (2”x4”, 4”x4”, and 6”x4”) of the microbiological testing procedure would affect the results. The surface areas that were evaluated were the stainless steel production tabletops at the point of entry (E), middle (M) and as the fish were leaving (L) the processing line, along with the trays that the tuna were carried into and out of the work area. The time intervals that were studied were after production (AP), after sanitation (AS), and before production (BP). Total aerobic plate counts (APC’s) were obtained and enumerated using 3M PetrifilmTM and incubating them at 35°C for 48 hours. No significant difference (P> 0.05) was found between AS’ and BP’s APCs. Overall, high APC’s were found at the AP time, as surface areas had not yet been sanitized. Even though a laboratory calibration curve for Log CFU’s and RLU’s was highly correlated (r2 = 0.9527), the plant’s CFU and RLU values were found not to correlate (r2 = 0.139).