Effects of superchilling on quality of crayfish (Procambarus clarkii): water migration, biogenic amines accumulation, and nucleotides catabolism

Effects of refrigerated (3.5 +/- 0.5 degrees C), iced (0 +/- 0.5 degrees C) and superchilled (-3.0 +/- 1.0 degrees C) storage on quality of crayfish (Procambarus clarkii) were evaluated by monitoring the water migration, microbial contamination, biogenic amines accumulation, and nucleotides catabolism during 21 days. The results indicated that superchilling was effective in accelerating the rate of water migration and reducing total volatile basic nitrogen, trimethylamine, total viable bacteria, Enterobacteriaceae and psychrotrophic bacteria of crayfish. Meanwhile, significant (P < 0.05) lower putrescine, cadaverine and tyramine contents were observed in superchilled sample (SS), whereas histamine concentrations were at lower levels (0.76-2.31 mu mol g(-1)) in all treatments. In addition, the predominant nucleotides degradation pathway in crayfish was the conversion of inosine monophosphate, which was accumulated massively (3.74 mu mol g(-1)) in SS at the end of storage. According to the dynamic changes of inosine and hypoxanthine contents, the shelf life of SS was prolonged to 15 days.