Protein degradation of olive flounder (Paralichthys olivaceus) muscle after postmortem superchilled and refrigerated storage

Abstract

The aim of this study was to investigate the effect of superchilling at −2°C in comparison with refrigerated storage at 4°C on the protein degradation of olive flounder (Paralichthys olivaceus) muscle. Flounder muscle softened and shear force value decreased markedly (P < 0.05) with prolonged storage time, while values of electrical conductivity, TCA-soluble peptide, free amino acids, and proteolysis index increased (P < 0.05). The changes were slowed down significantly in samples superchilled at −2°C (P < 0.05). The fracture of muscle fibre and formation of cracks were accelerated in the samples refrigerated at 4°C, and intercellular spaces were observed after 9 days of storage. Moreover, protein bands of myosin heavy chain (MHC), actin, tropomyosin, 97 kDa, 50 ~ 60 kDa and 35 ~ 36 kDa occurred in varying degrees of degradation with storage time. The results demonstrated that significant postmortem degradation of muscle proteins occurred with extending storage time, while the changes were retarded obviously in samples during superchilled storage.

Keywords

• Olive flounder
• protein degradation
• superchilling
• refrigeration