Abstract: This study attempted to elucidate the bacterial spoilage mechanism of salmon during cold chain storage and transport at 4 ℃. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), the traditional identification method and PCR were adopted to analyze the microflora changes in salmon during cold chain storage and transport at 4 ℃ and identify the specific spoilage organisms by testing the spoilage abilities of the dominant strains with yield factors. DGGE fingerprint showed that the diversity of bacterial species decreased during the cold storage of salmon, but the brightness of bands for Pseudomonas spp. and Shewanella spp. increased, which indicated that both strains became the predominant bacteria during the storage. Five dominant spoilage bacteria, Carnobacterium maltaromaticum LMA28, Pseudomonas syringae pv. syringae B728a, Pseudomonas fluorescens SBW25, Carnobacterium sp. WN1359 and Shewanella baltica OS678, were isolated and identified at the end of storage. After separately inoculating the 5 dominate spoilage organisms into sterilized salmon and refrigerating them for a certain period of time, their yield factors of TVB-N were 1.26 × 10-7, 1.25 × 10-7, 1.36 × 10-7, 1.08 × 10-7 and 1.03 × 10-7 mg TVB-N/CFU, respectively. These results showed that P. fluorescens SBW25 has the strongest spoilage ability for salmon, followed by C. maltaromaticum LMA28, P. syringae pv. syringae B728a, Carnobacterium sp. WN1359 and S. baltica OS678 successively.

Key words: salmon, microfloral changes, special spoilage organisms (SSOs), Pseudomonas fluorescens, spoilage ability