ABSTRACT
The effect of freezing and frozen storage of threadfin bream fish (Nemipterus japonicus) meat on the setting and gel-forming ability has been evaluated. The dynamic viscoelastic properties of fish meat during setting and thermal gelation process were evaluated using Controlled Stress Rheometer under oscillatory mode. A sharp decrease in setting ability was recorded immediately after freezing as revealed by storage modulus (Gꞌ) values. The transglutaminase (TGase) enzyme activity of fish meat decreased from the initial value of 81.09 to 51.46 U/g meat/min at the end of 200 days of frozen storage. A decrease in setting ability of fish meat beyond 160 days of frozen storage is probably related to lower TGase enzyme activity. The gel-forming ability was related to setting ability during the frozen storage period. Although the protein solubility showed a decreasing trend during 200 days of frozen storage, the decrease was not significant. The effect of freezing and frozen storage on calcium-activated adenosine triphosphatase (Ca2+-ATPase) enzyme activity of fish mince was significant (P < 0.05). A reduction in protein solubility and Ca2+-ATPase enzyme activity is an indication of aggregation/denaturation of myofibrillar proteins.
Funding
This work resulted from the project “SECURE FISH” that was funded by European Union 7th framework for research and technological development [grant number 289282].