Microbiological Quality of Catfish Frames Treated with Selected Phosphates

This study examined the effects of trisodium phosphate (TSP), sodium tripolyphosphate (STPP), and sodium metaphosphate (SMP) dipping solutions on the microbiological quality of catfish frames (the carcasses remaining after skinless boneless fillets are removed). Frames were dipped for 5 min in 10% phosphate solutions at 5°C, drained for 2 min, and analyzed for aerobic plate counts and total coliform counts. TSP reduced aerobic plate and total coliform counts by 1.0 and 2.5 log CFU/ml of rinse buffer, respectively. STPP reduced aerobic plate and total coliform counts by 0.3 and 1.0 logs, respectively. SMP did not reduce aerobic plate counts, but did decrease total coliform counts by 0.7 logs. The microbiological shelf life (time to reach 10⁷ CFU/ml) of the frames treated with TSP was 3 days longer than controls. Rinsing frames in water after phosphate treatment reduced the effectiveness of the dips. The results demonstrate that TSP was more effective than either STPP or SMP in reducing microbial numbers on the surface of the frames and provided a subsequent shelf life extension.