title: Control of natural microbial flora and Listeria monocytogenes in vacuum-packaged trout at 4 and 10 degrees C using irradiation.
abstract: The effect of gamma irradiation on the natural microflora of whole salted vacuum-packaged trout at 4 and 10 degrees C was studied. In addition, the effectiveness of gamma irradiation in controlling Listeria monocytogenes inoculated into trout was investigated. Irradiation at doses of 0.5 and 2 kGy affected populations of bacteria, namely, Pseudomonas spp., Brochothrix thermosfacta, lactic acid bacteria, H2S-producing bacteria typical of Shewanella putrefaciens, and Enterobacteriaceae, at both 4 and 10 degrees C. This effect was more pronounced at the higher dose (2 kGy) and the lower temperature (4 degrees C). Pseudomonads, H2S-producing bacteria typical of S. putrefaciens, and Enterobacteriaceae showed higher sensitivity to gamma irradiation than did the rest of the microbial species. Sensory evaluation did not show a good correlation with bacterial populations. On the basis of sensory odor scores, a shelf life of 28 days (2 kGy, 4 degrees C) was obtained for salted vacuum-packaged freshwater trout, compared with a shelf life of 7 days for the unirradiated sample. Under the same conditions, the growth of L. monocytogenes inoculated into the samples was suppressed by 2 log cycles after irradiation (2 kGy) and storage for up to 18 days at 4 degrees C.
authors.affiliation: Department of Chemistry, University of Ioannina, Greece. isavvaid@cc.uoi.gr
authors.forename: Ioannis N
authors.initials: IN
authors.lastname: Savvaidis
authors.forename: Panagiotis
authors.initials: P
authors.lastname: Skandamis
authors.forename: Kyriakos A
authors.initials: KA
authors.lastname: Riganakos
authors.forename: Nikolaos
authors.initials: N
authors.lastname: Panagiotakis
authors.forename: Michael G
authors.initials: MG
authors.lastname: Kontominas
mesh_terms: D000818:Animals; D003080:Cold Temperature; D015169:Colony Count, Microbial; D004307:Dose-Response Relationship, Radiation; D005514:Food Irradiation / Q000379:methods*; D018857:Food Packaging; D005720:Gamma Rays; D008089:Listeria monocytogenes / Q000254:growth & development / Q000528:radiation effects*; D009812:Odorants; D013649:Taste; D013696:Temperature; D013997:Time Factors; D014337:Trout / Q000382:microbiology*; D014618:Vacuum