Extension of the chilled storage life of smoked blue cod (Parapercis colias) by carbon dioxide packaging

Abstract

Commercially prepared smoked blue cod (Parapercis colias), packaged aerobically, under vacuum and in carbon dioxide controlled atmosphere packs, was stored at + 3°C and ‐ 1.5°C. Product stored aerobically on overwrapped polystyrene trays spoiled by 14 and 28 days respectively, and that in vacuum packs spoiled by 14 and 35 days respectively, when held at 3°C and ‐ 1.5°C. In contrast, product in carbon dioxide packs remained acceptable until the 3°C and ‐ 1.5°C storage trials ended after 49 and 113 days respectively. Microbial spoilage was first evident in overwrapped product stored aerobically and in vacuum‐packed product as offensive putrid amine‐like odours on pack opening. These odours were associated with the development of a predominantly Gram‐negative spoilage microflora. Extension of product life afforded by the use of carbon dioxide controlled atmosphere packaging is attributable to a significant extension of the lag phase before spoilage microflora proliferation commenced and to the selection of a low‐spoilage‐potential lactic‐acid‐bacteria‐dominated flora. Although the use of carbon dioxide packaging offers an export potential for chilled smoked blue cod, caution must be advocated until product safety, in respect to the growth of cold tolerant pathogens in the case of temperature abuse (>3°C), can be more fully evaluated.