High-pressure processing of mild smoked rainbow trout fillets (Oncorhynchus mykiss) and fresh European catfish fillets (Silurus glanis)

In order to determine the effects of high-pressure processing on the microbiological status of mild smoked rainbow trout fillets and fresh European catfish fillets, they were stored under refrigerated conditions for 41 or 7 days, respectively. For inoculation with Listeria monocytogenes or Escherichia coli, the fillets were minced and treated with 200, 400, or 600 MPa for 1 or 5 min at room temperature. HPP reduced L. monocytogenes by >6 log(10) CFU/g (P < 0.05) in both fish products, but subsequent growth was detected. Reductions of E. coli were >6 log(10) CFU/g (P<0.05), but during refrigerated storage, no growth was evident in samples. Spoilage microbiota were significantly reduced in the catfish fillets (P < 0.01), whereas the counts in trout fillets was low throughout the storage (around 1-2 log(10) CFU/g). In contrast to the nearly unaffected trout fillets, the catfish fillets appeared to be paler and like cooked products. Taking the results of the sensory analyses into account, high-pressure processing seems to be suitable for the treatment of mild smoked rainbow trout fillets, e.g. with a treatment with 600 MPa for 5 min. Industrial relevance: High-pressure processing is an innovative technology in food processing to prolong shelf life. Due to its ability to reduce the overall microbial load and at the same time maintain sensory and nutritional properties, it is especially in use for the treatment of fresh and ready-to-eat foodstuffs. However, it is also known that the range of effects of HPP is dependent on the matrix/food used as well as on the bacteria investigated. Therefore, it is necessary to consider each individual product. Most of the effects analysed in this study, such as microbiological reductions as well as alterations of the sensory characteristics, depended on the intensity of pressure and holding time. (C) 2015 Elsevier Ltd. All rights reserved.