Activity of smoke wood condensates against Aeromonas hydrophila and Listeria monocytogenes in vacuum-packaged, cold-smoked rainbow trout stored at 4 °C

Abstract

The antimicrobial effect of four smoke wood condensates against the psychrotrophic pathogens Listeria monocytogenes and Aeromonas hydrophila was tested in vacuum-packed cold-smoked rainbow trout ( Oncorhynchus mykiss) stored at refrigeration temperature. Salted trout samples were surface inoculated with L. monocytogenes or A. hydrophila, cold smoked, vacuum packaged and stored at 4 °C for 21 days. At different times of storage, samples were taken and analysed for L. monocytogenes and A. hydrophila by quantitative and qualitative procedures. All smoke extracts showed activity against A. hydrophila. However, only smoke extracts L1 and L2 were effective against L. monocytogenes. Although these extracts caused a reduction in viable cell counts of L. monocytogenes below the detectable level by surface plating procedure, this organism was detected by qualitative analysis in most of the samples. Finally, extracts L1 and L2 also reduced total viable cell counts to undetectable levels.