Distribution and behavior of Listeria monocytogenes in three lots of naturally-contaminated vacuum-packed smoked salmon stored at 2 and 10°C

The incidence, the number and the behavior of L. monocytogenes in three lots of naturally-contaminated vacuum-packed sliced smoked salmon, processed in different plants, were investigated during storage at 2 and 10°C. L. monocytogenes was isolated from 20 of the 100 packages stored at 2°C (16 from lot 1, 1 from lot 2 and 3 from lot 3) and from 12 of the 65 packages stored at 10°C (all from lot 1). The levels detected were 15, 20, 290, 1100 and >1100 cfu/g in 5 packages, all belonging to lot 1, and <10 cfu/g in the remaining samples. The high incidence of L. monocytogenes in lot 1 was assumed to be due mainly to the use of casual workers for the slicing and packing operations.