Nisin and ALTA 2341 inhibit the growth of Listeria monocytogenes on smoked salmon packaged under vacuum or 100% CO2.
The effects of nisin and ALTA 2341 on the growth of Listeria monocytogenes were assessed on smoked salmon packaged under vacuum or 100% CO2. Smoked salmon slices (pH 6.3) were inoculated with a cocktail of seven L. monocytogenes isolates at a level of approximately 2.5 log10 colony forming units (cfu) g-1. After inoculation, the surface of the smoked salmon slices was treated with either nisin (400 or 1250 IU g-1) or ALTA 2341 (0.1 or 1%). The smoked salmon was packaged and stored at 4 degrees C (28 d) or 10 degrees C (9 d). On untreated vacuum-packaged smoked salmon, L. monocytogenes grew by 3.8 log10 cfu g-1 at 4 degrees C and 5.1 log10 cfu g-1 at 10 degrees C. Growth was reduced on nisin- and ALTA 2341-treated vacuum-packaged smoked salmon. On the nisin-treated samples, L. monocytogenes increased by 2.5 (400 IU g-1) and 1.5 (1250 IU g-1) log10 cfu g-1 at 4 degrees C, and by 4.3 (400 IU g-1) and 2.7 (1250 IU g-1) log10 cfu g-1 at 10 degrees C. With the ALTA 2341-treated samples, L. monocytogenes increased by 2.8 (0.1%) or 1.6 (1.0%) log10 cfu g-1 at 4 degrees C, and 3.3 (0.1%) or 3.6 (1.0%) log10 cfu g-1 at 10 degrees C. The growth of L. monocytogenes was retarded by packaging the smoked salmon in 100% CO2. On untreated smoked salmon, only a 0.8 log10 cycle increase was observed at 10 degrees C. Under all the other conditions tested with 100% CO2, L. monocytogenes was detected but growth was prevented.
Szabo
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Food Science Australia, North Ryde, Australia. Lisa.Szabo@foodscience.afisc.csiro.au
Cahill
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D001430:Bacteriocins / Q000494:pharmacology*; D002245:Carbon Dioxide / Q000494:pharmacology; D005396:Fish Products / Q000382:microbiology*; D018857:Food Packaging / Q000379:methods*; D005520:Food Preservatives / Q000494:pharmacology*; D008089:Listeria monocytogenes / Q000187:drug effects*; D009561:Nisin / Q000494:pharmacology; D014618:Vacuum
C119555:ALTA 2341; D001430:Bacteriocins; D005520:Food Preservatives; D009561:Nisin; D002245:Carbon Dioxide