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Textural changes as well as protein degradation during frozen storage of Nile tilapia (Oreochromis niloticus) at −18C for 150 days were studied. Salt-soluble protein and protein solubility decreased significantly during the frozen storage period. Sodium dodecyl sulfate polyacrylamide gel electrophoresis was performed, and no visible changes in myosin heavy chain were observed up to 90th day of frozen storage period; however, the thickness of band was found to decrease thereafter. A new lighter band with molecular weight of 29 kDa was found on 120th and 150th day of sampling period. Actin was found more resistant to proteolysis. Texture profile analysis revealed that hardness 1, hardness 2, gumminess and chewiness gradually decreased up to 120th day, but showed an increase thereafter. Although sensory attributes decreased with the progress of frozen storage period, the fish was in acceptable condition on 150th day. Gradual toughening of muscle was recorded by the sensory panelists. PRACTICAL APPLICATIONThe popularity of tilapia is gaining importance for the development of different value-added fish products as well as for canning purposes. Therefore, it is important from the part of fish processor to know the changes of protein and texture profile during frozen storage. Although there was protein degradation and changes in texture profile during the study period of 150 days, the fish was in acceptable condition. , etc.) are significantly different (P < 0.05) with respect to period of storage.STUDY OF TILAPIA DURING FROZEN STORAGE K. SUBBAIAH ET AL.

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Studies were conducted to assess the chemical and quality changes in washed silver carp mince when frozen and stored at −20C with or without cryoprotectants. A previous washing step has led to a positive effect on fish quality according to marked content decreases in expressible moisture, volatile basic amines, free fatty acids and thiobarbituric acid reactive substances; such quality performances were maintained throughout the frozen storage. On the other hand, addition of cryoprotectants enhanced the quality life of mince as far as gel‐forming ability was concerned. Based on the gel‐forming ability, the shelf life of mince with cryoprotectants was found 135 days against 90 days for the mince stored without cryoprotectants. PRACTICAL APPLICATION Silver carp (Hypophthalmichthys molitrix) has acquired great attention because of its increasing farming production and application in the surimi‐product commercialization. Because of relatively low market price in fresh condition, the fish received less attention from the researchers to study its technical feasibility. This work focuses on the quality life of washed silver carp mince when frozen stored at −20C. The shelf life was assessed based on the gel‐forming ability of the mince because this functional property is considered most important for product development.

The gel properties of sutchi catfish surimi prepared by conventional washing and alkaline-saline washing method were studied for four washing cycles. Decrease (p < 0.05) in myoglobin content was found in alkaline washing process compared to conventional washing at each washing cycle. The highest hardness, breaking force and deformation was observed in gels prepared from alkaline-saline washing method. Whiteness in conventional washed surimi gels increased non-significantly (p < 0.05) compared to alkaline-saline-washed surimi gels. Protein bands on Sodium dodecyl sulfate polyacrylamide gel electrophoresis indicated that the protein extractability was more in alkaline-saline washing and disappearance of bands in conventional washing method was observed between 116 and 45 kDa indicating less yield of protein.