To determine the effectiveness of different sampling procedures, 200 frozen catfish known to be contaminated with Salmonella were divided into 350 samples. Variables in sampling included anterior and posterior portions of fish, blending, immersion, swabbing, rinsing and incubation at elevated temperatures. The composite of blended anterior and posterior samples incubated at 43 C and immersion of whole fish incubated at 35 C showed the highest number of positive samples, 50% and 42%, respectively. The contact method of swabbing (14%) and rinsing (14%) were the least effective of the methods examined. The anterior (visceral cavity area) portions of the fish seemed to be more highly contaminated (38% positive) than the posterior portion (26% positive). These data show that the sampling procedure can greatly affect recovery of Salmonella from fresh water catfish. Overall levels of Salmonella were low and the hazards of cross-contamination with other foods seem remote.
1Ralston Purina Company.
2Texas A&M University.