Influence of Freshness and Frozen Storage Temperature on Quality of Thawed Cod Fillets Stored in Modified Atmosphere Packaging

Abstract

The effects of keeping cod fillets in air at 0°C for 1 or 8 d prior to modified atmosphere packaging (MAP) and subsequent frozen storage at -20°C and -30°C for 6 wk were studied. Quality attributes of thawed MAP cod fillets stored at 2°C for up to 17 d were evaluated. The known specific spoilage organism of fresh MAP cod,Photobacterium phosphoreum , was found in levels of 2.3 and 5.8 Log (cfu/g) after 1 and 8 d of chill storage in air at 0°C, respectively. Frozen storage at both -20°C and -30°C for 6 wk reduced numbers of P. phosphoreum to below the limit of detection. After chill storage at 2°C, P. phosphoreum was not detected in cod fillets stored frozen at -20°C. Significant growth of P. phosphoreum and production of TMA during chill storage at 2°C were only observed in cod fillets kept for 8 d in air at 0°C prior to frozen storage at -30°C. Frozen storage odour and taste developed in thawed MAP cod fillets during chill storage but they were substantially more pronounced in cod fillets stored 8 d in air at 0°C before freezing. The present study clearly showed the need for fresh raw material when producing thawed chilled cod fillets packed in modified atmosphere. Consequently, it was concluded that 'frozen at sea' raw material in combination with MAP seems to be a promising technology, combining the inhibitory effect on microbial growth and TMA production for the manufacture of prime quality thawed MAP cod fillets for retail. © 2000 Academic Press.