Postmortem muscle protein degradation during ice-storage of Arctic (Pandalus borealis) and tropical (Penaeus japonicus and Penaeus monodon) shrimps:: a comparative electrophoretic and immunological study

Water-, low-salt- and high-salt-soluble protein fractions from the abdominal muscles of Pandalus borealis, Penaeus japonicus and Penaeus monodon extracted immediately after death and after 5, 16, 24, 48, 72, 96 and 120 h (P borealis) or 16, 22, 43, 71 and 92 h (Penaeus spp) of ice-storage were analysed by one- and two-dimensional electrophoresis and immunological techniques. The most evident effect in P borealis was the decrease in the relative amount of myosin heavy chain (MHC) and a concomitant increase in the number and intensity of bands of molecular size about 100kDa crossreacting with anti-MHC antiserum. NMC degradation of P borealis was confirmed by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) of partially isolated native myosin. Other prominent features were the disappearance of bands of about 67 and 50kDa after 24h and the appearance of a band of slightly less than 50kDa after 5 h of ice-storage. These last bands showed the potential to be used as freshness markers. One spot tentatively identified as desmin did not suffer significant changes in any of the three species. Two bands (about 100 and 96kDa) gave a positive reaction with the a-actinin antibody in the zero-time extract of P borealis, but after 24h only one faint 96kDa band was detected. In contrast, the extracts of P japonicus and P monodon did not suffer significant alterations during the examined period, and even after 92h of ice-storage only the 100kDa anti-a-actinin cross-reacting band was clearly visible in the high-salt extract of P japonicus. (C) 2001 Society of Chemical Industry.