Heat Resistance of Bacteria Isolated From Preparations Based on Seafood 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 D₇₀ 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, p₇₀⁶ = 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 P₇₀⁹ = 30 min.