Thawed Cod Fillets Spoil Less Rapidly Than Unfrozen Fillets When Stored under Modified Atmosphere at 2°C

Area of Science:

• Food Science
• Microbiology
• Seafood Technology

Background:

• Modified Atmosphere Packaging (MAP) is used to extend the shelf life of fresh fish.
• Frozen storage is a common preservation method for seafood, but its effect on MAP products requires investigation.

Purpose of the Study:

• To evaluate the impact of two months of frozen storage (-20°C) on the spoilage characteristics and shelf life of thawed MAP cod fillets.
• To compare the quality of thawed MAP cod fillets with fresh MAP cod fillets.

Main Methods:

• Cod fillets were frozen for two months at -20°C, then thawed and packaged under modified atmospheres (CO2-containing, with/without O2).
• Spoilage was assessed through chemical analyses and sensory evaluation during storage at 2°C.
• Thawed MAP cod was compared to fresh MAP cod stored under similar conditions.

Main Results:

• Shelf life of MAP cod extended from 11-12 days (fresh) to over 20 days (thawed).
• Reduced spoilage indicators (e.g., trimethylamine, amine odor/taste) were observed in thawed MAP cod.
• Inactivation of Photobacterium phosphoreum during frozen storage was identified as a key factor for shelf life extension.

Conclusions:

• Frozen storage followed by MAP packaging offers a viable strategy to enhance cod fillet shelf life and stability.
• This approach allows for greater flexibility in production and distribution of seafood products.
• Minor drawbacks include increased dimethylamine, drip loss, and a slight frozen storage flavor in thawed fillets.