PROTEIN DEGRADATION AND INSTRUMENTAL TEXTURAL CHANGES IN FRESH NILE TILAPIA (OREOCHROMIS NILOTICUS) DURING FROZEN STORAGE

摘要

Textural changes as well as protein degradation during frozen storage of Nilerntilapia (Oreochromis niloticus) at −18C for 150 days were studied. Salt-solublernprotein and protein solubility decreased significantly during the frozen storagernperiod. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was performed,rnand no visible changes in myosin heavy chain were observed up to 90th day ofrnfrozen storage period; however, the thickness of band was found to decrease thereafter.rnA new lighter band with molecular weight of 29 kDa was found on 120thrnand 150th day of sampling period. Actin was found more resistant to proteolysis.rnTexture profile analysis revealed that hardness 1, hardness 2, gumminess andrnchewiness gradually decreased up to 120th day, but showed an increase thereafter.rnAlthough sensory attributes decreased with the progress of frozen storage period,rnthe fish was in acceptable condition on 150th day. Gradual toughening of musclernwas recorded by the sensory panelists.