Characterisation of the spoilage microbiota in raw salmon (Salmo salar) steaks stored under vacuum or modified atmosphere packaging combining conventional methods and PCR–TTGE

Abstract

In order to characterise the spoilage related to microbiota of raw salmon, a combination of culture-dependent and -independent methods, including PCR-TTGE, was used to analyse 3 raw salmon batches stored for 3 days at chilled temperature in modified atmosphere packaging (MAP) (50% CO₂/50% N₂) or under vacuum. Sensory evaluation, microbiological enumeration and chemical analysis were performed after 3, 7 and 10 days of storage. At the onset of spoilage, 65 bacterial isolates were picked from the plates. Thus, 13 different genera or species were identified by phenotypic and molecular tests: Serratia spp., Photobacterium phosphoreum, Yersinia intermedia, Hafnia alvei, Buttiauxella gaviniae, Pseudomonas sp., Carnobacterium maltaromaticum, Carnobacterium divergens, Lactococcus piscium, Lactobacillus fuchuensis, Vagococcus carniphilus, Leuconostoc gasicomitatum and Brochothrix thermosphacta. The PCR-TTGE profiles and band identification enabled a shift of the dominant populations during the storage to be visualised for all the batches, probably due to the temperature change and the packaging. At the beginning of storage, Pseudomonas sp. dominated the raw salmon microbiota while in the following days (7 and 10), P. phosphoreum and L. piscium were identified as the main bacterial groups. This study enhances the knowledge of MAP and vacuum-packed raw salmon spoilage microbiota.

Characterization of <i>N</i>-acyl homoserine lactones (AHLs) producing bacteria isolated from vacuum-packaged refrigerated turbot (<i>Scophthalmus maximus</i>) and possible influence of exogenous AHLs on bacterial phenotype

“…These bacterial species are food-borne health-hazard opportunistic pathogens leading to pneumonia, intravenous catheter-associated infections, and osteomyelitis (Chan et al, 2013). Both of the bacterial strains widely exist in vacuum-packed refrigerated or iced raw food materials and have been reported to be involved in the spoilage of various aquatic food products, i.e., they have been isolated from spoiled cooked whole tropical shrimp (Penaeus vannamei) and spoiled raw salmon (Salmo salar) fillets stored under modified atmosphere packaging (Macé et al, 2012(Macé et al, , 2013.…”

Development of a Rapid Real-Time PCR Method as a Tool To Quantify Viable Photobacterium phosphoreum Bacteria in Salmon (Salmo salar) Steaks

“…However, this packaging allows the growth of CO 2 -resistant bacteria, including Gram-positive lactic acid bacteria and the Gram-negative bacterium Photobacterium phosphoreum (2)(3)(4). The latter has been identified as the specific spoilage organism (SSO) responsible for trimethylamine production and sensory spoilage of MAP cod (5,6) and as the main spoilage bacterial species of several chilled marine fish, including cod, garfish, halibut, saithe, salmon, and shrimp (7)(8)(9)(10)(11)(12)(13)(14)(15).…”

Effect of Activated Plastic Films on Inactivation of Foodborne Pathogens

“…This is important since the shelf life of seafood products can be shortened considerably by spoilage bacteria. Pseudomonads have been reported from vacuum and modified atmosphere packaged salmon products [17][18][19]. Under chilled, aerobic storage conditions, Pseudomonas and related genera such as Shewanella are the most common spoilage organisms [19].…”