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The growth, survival, and death of Listeria monocytogenes were studied in a synthetic medium as a function of temperature, NaCl content, and amount of liquid smoke, and the findings were validated in smoked fish products. The smoke preservative compound was simulated by adding liquid smoke, and the concentration was expressed as phenol concentration. The growth of L. monocytogenes was limited at a temperature as low as 4 degrees C or at a phenol concentration as high as 20 ppm. The predicted values were obtained using a mathematical model established in liquid medium in a previous study. They accurately fit values observed in L. monocytogenes challenge tests on smoked fish. After 21 days of storage the deviation between the predicted and experimental values was within 0.5 log for 60% of the data. This model may be useful in predicting Listeria contamination in smoked fish. Moreover, this study emphasizes the importance of phenol concentration to control the growth of Listeria spp. in smoked food products.

The market for vacuum-packed pasteurized seafood products is developing rapidly. The stability and safety of pasteurized products rely on pasteurization processes and subsequent storage at refrigeration temperatures. The aim of this work was to study the heat resistance of characteristic bacterial flora responsible for spoilage in pasteurized seafood products and to determine the minimal pasteurizing value required for the destruction of nonsporeforming bacteria. The D T and z-values were determined for various bacteria selected from among the most heat-resistant bacteria isolated from seafood products ( Pseudomonas paucimobilis , Pseudomonas putida , Micrococcus varians , Enterococcus faecium and Staphylococcus aureus ). Thermal resistance was measured in different media (fish fillet, fish terrine and M/15 phosphate buffer). The most heat-resistant microorganism found was Pseudomonas paucimobilis : the D 70 varied between 1.16 and 3.36 min, and the z-value, between 5.8 and 9.1°C, depending upon the medium. The minimal pasteurizing values required to destroy a sufficient proportion of nonsporulated bacteria were determined. In France, the pasteurizing value is designated P T Z . The reference temperature was 70°C (the official reference temperature in France). In fish, the minimal pasteurizing value, p 70 6 = 15 min, should be applied to ensure the destruction of almost any vegetative forms of bacteria. In a fish terrine, the minimal pasteurizing value should be P 70 9 = 30 min.