Microbiological quality and listeria-contamination of vacuum packaged smoked salmon

The microbiology of 40 samples of vacuum packaged smoked or ,,graved", sliced salmon were analysed as part of a survey. The mesophilic, aerobic total count varied on the day of purchase between < 10(2) cfu/g and 1.1 x 10(8) cfu/g. At the end of the indicated "consume-by" date, 30 (75 %) samples exceeded the suggested guideline value of 10(6) cfu/g, whilst in 16 (40 %) of the samples the total detectable microbial numbers exceeded 10(8) cfu/g; the numbers of two samples actually exceeded 10(9) cfu/g. In 80 % of these highly contaminated samples, lactic acid bacteria were the dominating population, partly together with Enterobacteriaceae and pseudomonads. Carnobacteria dominated the microbial population in 14 samples at the end of the "consume-by" date. The enterobacteria and pseudomonads comprised different proportions of the microbial load. Whereas they were not detectable in 8 samples at the end of the "consume-by" date, these microbial numbers exceeded the suggested guideline value (10(4) cfu/g), and the load of 18 of these samples even exceeded the suggested alarm value of 10(5) cfu/g. Listeria were detected in 26 samples (65 %) at the day of purchase. By the end of the "consume-by" date, 11 samples (27.5 %) exceeded the alarm value for listeria of 10(2) cfu/g, with numbers of up to 1.5 x 10(6) cfu/g. L. monocytogenes has been isolated most frequently among the listerias (33 of 44 isolates). The contamination level is considered alarmingly high for the samples investigated.