Microbiological contamination of tilapia (Oreochromis niloticus) during the fish processing

The aim of this study was to evaluate the microbiological contamination of the tilapia (Oreochromis niloticus) fillet and the water used at various stages of processing in an industry located in the metropolitan area of Curitiba - PR. Samples were collected in five stages of the fillet processing. Water was collected in the two first steps of processing and the tilapia fillet was collected in the last three steps. Collection and analysis of samples were performed in four replicates. Tilapia fillets were subjected to the viable count of aerobic psychrotrophic, total coliform and Escherichia coli, coagulase-positive Staphylococcus and Salmonella sp. Water samples were subjected to the most probable number of coliform and Escherichia coli. Psychrotrophic count ranged from 4.3 x106 CFU/ g for fillet after de-skinning to 2.6 x107 CFU/ g for fillet after packaging. The occurrence of coagulase-positive Staphylococcus was only detected in fillet after packing and the viable number was lower than 103 CFU/ g. Salmonella was detected in tilapia fillet after de-skinning and after removing the central spine. With regard to the water contamination by total coliform and Escherichia coli numbers were in accordance to the standard established by Brazilian law. However, fillet samples showed coliform and E. coli contamination at all stages of tilapia processing with values ranging from 5 x 101 to 4.5 x 103 CFU/ g of total coliform and <10 to 3.0 x 102 CFU/ g of Escherichia coli. The results showed the need for better microbiological control of the fillet and the water during the tilapia processing, because high counts of spoilage microorganisms and the presence of pathogens were found in all studied processing stages. O objetivo foi avaliar a contaminação microbiana do filé de tilápia (Oreochromis niloticus) e da água utilizada em diferentes etapas do beneficiamento desse pescado em uma indústria localizada na região metropolitana de Curitiba – PR. As amostras foram coletadas com quatro repetições e em cinco etapas do processamento do filé. Sendo duas etapas escolhidas para a coleta de amostras de água e três etapas para a coleta de filé. Os filés foram submetidos à contagem de aeróbios psicrotróficos, contagem de coliformes totais e Escherichia coli, contagem de Staphylococcus coagulase positiva e pesquisa de Salmonella sp. Nas amostras de água foi avaliado o número mais provável de coliformes totais e de Escherichia coli. A contagem de psicrotróficos variou de 4,3 x 106 UFC/g para o filé após a retirada da pele a 2,6 x 107 UFC/g para o filé embalado. A ocorrência de Staphylococcus coagulase positiva foi verificada somente nas amostras de filé após a embalagem e o valor observado mostrou-se inferior a 103 UFC/g. Foi detectada a presença de Salmonella sp em amostras de filé obtidas após a retirada da pele e após a retirada do espinho central. Com relação à contaminação por coliformes totais e Escherichia coli a água da recepção e a água da lavagem dos peixes mostraram valores acima do permitido pela legislação e as amostras de filé apresentaram-se contaminadas por esses microrganismos em todas as etapas estudadas apresentando valores de 5 x 101 a 4,5 x 103 UFC/ g de coliformes totais e