ABSTRACT
Listeria monocytogenes and other Listeria spp. have been isolated from seafoods on a regular basis since 1987. A relatively high incidence of the organism (6-36%) in ready-to-eat cold smoked salmon and cooked fish products has raised concern about the survival and growth potential of this organism in seafoods, as these products are not processed further before consumption. L. monocytogenes grows well at refrigeration temperature on most seafoods, but the sources of contamination in ready-to-eat fish products are still unknown. This paper reviews the knowledge available in order to make recommendations on control options and avenues for future research.
Subject(s)
Listeria monocytogenes/isolation & purification , Seafood/microbiology , Bacteriological Techniques , Food Contamination/prevention & control , Food Handling , Food Preservation , Hot Temperature , Listeria monocytogenes/growth & developmentABSTRACT
The heat resistance of two strains of Listeria monocytogenes in sous-vide cooked fillets of cod and salmon was investigated. Fish sticks of 5 g were inoculated, vacuum-packed and heated at different combinations of time and temperature (58-80 degrees C). Time-temperature combinations allowing survival and time-temperature combinations at which the bacteria were destroyed, were used to determine D- and z-values. D-values were in the range of what has been published for other food products. D60-values were between 1.95 and 4.48 min depending on the strain and the fish. Both strains were one-four-times more heat resistant in salmon than in cod, showing the importance of the heating menstruum. This difference may be due to the higher fat content in salmon as compared to cod. Z-values were calculated to be 5.65 and 6.4 degrees C, respectively, for the two strains. The suitability of methods for heat resistance experiments and the survival of L. monocytogenes in sous-vide cooked fish fillets are discussed.
