Change of muscle proteins in Nile tilapia fillets during iced storage

We extracted different solubility proteins and structure proteins from Nile tilapia ( Oreochromis niloticus) fillets during iced storage to investigate the change of their muscle proteins. The degradation of total soluble, water soluble, high-salt soluble and low-salt soluble proteins was analyzed by SDS-PAGE. The high-salt soluble protein content declined from84. 99 mgg-1 to 49.47 mgg-1 ; water-soluble protein declined from72.27 mgg-1 to 18.37 mgg-1 ; low salt soluble protein dropped from11.15 mgg-1 to 3.39 mgg-1 . In the three different structures of proteins, the decline of myofibrillar protein content is most obvious ( decreased from122.10 mgg-1 to 48.65 mgg-1 , P 0.05) , and the content of myosinogen decreased from37. 79 mgg- 1 to 26.57 mgg- 1 ( P 0.05) , while myostromin had no obvious change ( P 0.05) . The decrease of myosin heavy chain, actin, tropomyosin and some other protein bands in SDS-PAGE patterns indicates degradation of these proteins. Some new bands appeared at the last phase of storage.