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.

The effect of garlic's aqueous extract (GAE) during refrigerated storage of the restructured products from Pangasius (Pangasianodon hypophthalmus) was evaluated. Protein and lipid oxidation, protein pattern on SDS-PAGE, TPC as well as WHC, gelling properties, texture profiles and whiteness of the surimi gel was evaluated periodically during a refrigerated storage period of 20 days. Increase of water holding capacity in GAE added gels indicated stronger protein network formation, whereas, decrease of protein solubility suggested formation of protein aggregates during gelation process. Lipid oxidation decreased in treated samples but the rate of increase varied, depending upon the concentration of GAE. Protein carbonyl content increased during storage, but slow increase in treated samples. Gel strength in treated samples increased and accompanied by thickening of myofibrillar head chain. Hardness, adhesiveness and gumminess parameters affected most due to addition of GAE. Sensory analysis revealed that the RP with 1 % GAE preferred most and control was acceptable upto 12 days.

'Kalia', a popular preparation of Rohu fish, packed in four-layered laminated retort pouch was processed in a steam/air mixture over-pressure retort at 121.1°C to three different F 0 values of 7, 8 and 9 min. Time-temperature data were collected during heat processing using an Ellab Sterilization Monitoring System. Texture profile such as hardness, springiness, gumminess and chewiness decreased as the F 0 value increased. The L* values decreased whereas a* and b* values increased with increasing F 0 value. Based on the commercial sterility, sensory evaluation, colour and texture profile analysis, F 0 value of 8 min and cook value of 66 min, with a total process time of 41.7 min at 121.1°C was found satisfactory for the preparation of Rohu fish curry (Kalia) in retort pouches.

Boneless fish ball from Rohu fish (Labeo rohita) in gravy packed in four-layered laminated retort pouch was processed in a steam/air mixture over-pressure retort at 121.1C to three different F 0 values of 6, 7 and 9 min. Time-temperature data were collected during heat processing using an Ellab Sterilization Monitoring System. Texture profiles such as hardness, springiness, gumminess and chewiness decreased as the F 0 value increased. Highest cohesiveness coincided with the highest score of texture. The L* values decreased whereas a* and b* values increased with increasing F 0 values. Based on the commercial sterility, sensory evaluation, color and texture profile analysis F 0 value of 7 min and cook value of 67.48 min, with a total process time of 42.21 min at 121.1C was found satisfactory for the development of retort pouch processed "Rohu ball" in curry. PRACTICAL APPLICATIONFish ball is a value added food product convenient to prepare and consume and thus suitable for the changed lifestyle of urbanized people. The boneless fish ball from Rohu fish is an improvisation of use of freshwater fishes where their small bone contents restrict use to a greater extent. Incorporation of fish ball in curry will add to a new dimension toward value addition of freshwater fish particularly in North-east region. Fish ball in curry processed in retort pouch would add to a new appropriate channel to Supermarket chain.

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.