High Oxygen Packaging of Atlantic Cod Fillets Inhibits Known Spoilage Organisms, but Sensory Quality Is Not Improved Due to the Growth of Carnobacterium/Carnobacteriaceae

Summary

Improved quality control and prolonged shelf life are important actions in preventing food
waste. To get an overview of the bacterial diversity of fillets from live stored mature Atlantic cod,
bacterial isolates were identified before and after storage (air and vacuum) and freezing/thawing.
Based on the load of dominating bacteria, the effect of different packaging methods and a short
freezing/thawing process on prolonged shelf-life was evaluated (total viable counts, bacteriota,
sensory attributes, and volatile components). Hand filleted (strict hygiene) cod fillets had a low initial
bacterial load dominated by the spoilage organism Photobacterium, whereas industrially produced
fillets had higher bacterial loads and diversity (Pseudomonas, Arthrobacter, Psychrobacter, Shewanella).
The identified bacteria after storage in vacuum or air were similar to the initially identified bacteria.
Bacteriota analysis showed that a short time freezing/thawing process reduced Photobacterium while
modified atmosphere packaging (MAP; 60% CO2/40% O2 or 60% CO2/40% N2) inhibited the growth
of important spoilage bacteria (Photobacterium, Shewanella, Pseudomonas) and allowed the growth
of Carnobacterium/Carnobacteriaceae and Acinetobacter. Despite being dominated by Photobacterium,
fresh fillets stored in MAP 60% CO2/40% N2 demonstrated better sensory quality after 13 days of
storage than fillets stored in MAP 60% CO2/40% O2 (dominated by Carnobacterium/Carnobacteriaceae).
Carnobacterium spp. or other members of Carnobacteriaceae may therefore be potential spoilage
organisms in cod when other spoilage bacteria are reduced or inhibited.