Temperature and Deteriorative Changes in Postrigor Cod Muscle Stored up to 14 Days in the Superchill Range, −1 to −4 C

The effect of several storage temperatures in the superchill range (−1, −1.6, −2.3, −3, and −4 C) on bacterial and autolytic spoilage processes in postrigor cod muscle was assessed. Changes in trimethylamine, hypoxanthine, and pH, monitored as spoilage indicators, were slight during superchilling at all temperatures between −1 and −4 C for 3 and 6 days, and 14 days at −4, indicating inhibition of bacterial action. However, at −1.6 and at 0 C spoilage thresholds were reached in 10 and 6 days, respectively. Salt extractable protein remained unchanged, but mild lipid hydrolysis occurred at all temperatures.In samples superchilled for 3 or 6 days, then thawed and held at +5 or +10 C, spoilage processes resumed as judged by trimethylamine, hypoxanthine, and free fatty acid increases. Changes at +5 C in samples that had been held at −1 and at −1.6 were slightly slower than in controls at 0 C similarly treated, but in samples presuperchilled at −3 and −4 spoilage changes at +5 were markedly delayed. No deleterious effect on protein extractability was detected. Thus superchilling at −4 C for 3 and for 6 days was very effective, increasing the postfilleting storage life to 8 and 11 days, respectively, as compared to 5 days for controls held at 0 for 3 days before transfer to 5 C.