Physicochemical and microbiological changes in postmortem crayfish (Procambarus clarkii) stored at 4 °C and 25 °C

Abstract

SummaryThe physicochemical and microbiological parameters of postmortem crayfish stored at 4 °C and 25 °C were evaluated in order to reduce safety risks of crayfish from temperature abuse during transportation and storage. Results showed that hepatopancreas of postmortem crayfish had significantly higher contents of total volatile basic nitrogen, biogenic amines (BAs) and higher microbial loads than tail meat, regardless of storage temperature. Enterobacteriaceae and Pseudomonas counts reached log 6.41 log10 CFU g−1 and 6.31 log10 CFU g−1 in hepatopancreas of crayfish at 25 ℃ for 6 h. Putrescine and cadaverine were the main BAs in tail meat with levels of 28.18 ± 0.73 mg kg−1 and 187.32 ± 3.57 mg kg−1, respectively, whilst cadaverine, spermidine and spermine were the major BAs in hepatopancreas, reaching 283.45 ± 3.95 mg kg−1, 62.87 ± 9.02 mg kg−1 and 155.31 ± 4.55 mg kg−1, respectively, after postmortem storage at 25 °C for 12 h. With time increasing, Acinetobacter, Flavobacterium, Aeromonas and Chryseobacterium at 25 °C and Acinetobacter, Flavobacterium, Psychrobacter at 4 °C in tail meat as well as Bacteroides and Muribaculaceae at 25 °C, and Acinetobacter, Psychrobacter at 4 °C in hepatopancreas, gradually became the major genus at the end of storage. Based on the results of spoilage microorganisms and biogenic amines, crayfish stored at 4 °C and 25 °C could be edible within 24 h and 6 h, respectively.