Microflora assessments using PCR-denaturing gradient gel electrophoresis of ozone-treated and modified-atmosphere-packaged farmed cod fillets.
Denaturing gradient gel electrophoresis (DGGE) of a PCR-amplified 16S rDNA sequence was used to characterize changes in the microbial flora caused by ozone (O3) treatment of farmed cod (Gadus morhua). Portions of cod were produced under controlled conditions, bathed in fresh water supplemented with 2 ppm of O3 for 30 min, and packaged in modified atmosphere (MA: 60% CO2 and 40% N2) before 4 degrees C storage. Control samples were packaged in MA or air, without prior O3 treatment. Samples were analyzed by PCR-DGGE to determine the predominant bacterial flora and to examine possible differences in the microbial community due to O3 treatment. The DGGE analysis during the storage period showed that the O3 treatment produced no significant difference in the microbial flora compared with the controls. Sequencing of 16S rDNA detected the specific spoilage bacteria Photobacterium phosphoreum, Pseudomonas spp., Shewanella baltica, and Shewanella putrefaciens as the predominant bacteria in all samples. PCR-DGGE results were supported by culture and sensory analyses used in predicting product shelf life. Aerobic plate count, H2S-producing bacteria, and psychrotrophic bacterial counts demonstrated no significant extension of the shelf life of MA-packaged, O3-treated cod fillets.
Norconserv AS, Seafood Processing Research, P.O. Box 327, N-4002 Stavanger, Norway.
Maria Befring
MB
Hovda
Morten
M
Sivertsvik
Bjørn Tore
BT
Lunestad
Jan Thomas
JT
Rosnes
D000818:Animals; D002245:Carbon Dioxide / Q000378:metabolism; D015169:Colony Count, Microbial; D003257:Consumer Product Safety; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel / Q000379:methods; D005506:Food Contamination / Q000032:analysis / Q000517:prevention & control; D005516:Food Microbiology; D018857:Food Packaging / Q000379:methods*; D005519:Food Preservation / Q000379:methods*; D048389:Gadus morhua / Q000382:microbiology; D006801:Humans; D009584:Nitrogen / Q000378:metabolism; D010083:Oxidants, Photochemical / Q000494:pharmacology; D010100:Oxygen / Q000378:metabolism; D010126:Ozone / Q000494:pharmacology*; D010776:Photobacterium / Q000254:growth & development*; D016133:Polymerase Chain Reaction / Q000379:methods; D011549:Pseudomonas / Q000254:growth & development*; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D017747:Seafood / Q000382:microbiology* / Q000592:standards; D013997:Time Factors; D014618:Vacuum
D004269:DNA, Bacterial; D010083:Oxidants, Photochemical; D012336:RNA, Ribosomal, 16S; D002245:Carbon Dioxide; D010126:Ozone; D009584:Nitrogen; D010100:Oxygen