49B-9 |
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B. H. HIMELBLOOM, Fishery Industrial Technology Ctr., Univ. of Alaska, Fairbanks, 118 Trident Way, Kodiak, AK 99615-7401, S. M. Vitt, Fishery Industrial Technology Center, University of Alaska Fairbanks, 118 Trident Way, Kodiak, AK 99615-7401, and C. Crapo, Fishery Industrial Technology Center, Univ. of Alaska, Fairbanks, School of Fisheries & Ocean Sciences, 118 Trident Way, Kodiak, AK 99615-7401. Current processing practices can not always prevent L. monocytogenes contamination in cold-smoked salmon. New techniques for inactivating L. monocytogenes must be developed to assist the industry in providing safe products. The objective was to develop a brining process for cold-smoked salmon that includes liquid smoke and acidulant at concentrations bactericidal to L. innocua. Tube assays were conducted using BHI supplemented with liquid smoke (CharSol Supreme [CS]) plus acetic acid, lactic acid or sodium diacetate. Listeria monocytogenes ATCC 19115 and L. innocua ATCC 33090 were grown overnight in BHI at 30oC. Tubes were inoculated and incubated for 22-24 hr, optical density readings at 600 nm and pH were recorded. Gutted pink salmon were thawed, filleted and rinsed. Brined fillet portions were dipped up to 1 hr at 25oC in acidulant solutions, then in 60-100% CS for 2-5 min and drained. An overnight culture of L. innocua was centrifuged, the pellet resuspended and 0.5 ml spread on 100-g fillet portions. A smokehouse was used only for drying of the samples at 21oC for 16 hr. Samples were stomached with sterile PW and serially diluted. Aliquots were streaked on modified Oxford (MOX) agar and incubated at 30oC for 24-48 hr. Color readings (L*a*b*) using a Minolta color meter and pH were recorded. Tube assays showed that the combination of 0.1-0.2% acetic or lactic acid and 0.1-0.5% CS were inhibitory to Listeria monocytogenes and L. innocua. Dipping of brined salmon in concentrations of 5-10% acetic acid followed by 2 min in 60-100% CS and drying resulted in 3-4 log reductions of L. innocua. The CS-treated salmon were 10-20% darker than controls while the treatment combination of acid and CS resulted in pH of 4.9-5.2. These results will be useful to the smoked seafood industry for enhancing consumer safety of minimally preserved products.
Session 49B, Aquatic Food Products: General
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