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Two pelagic underutilised fish species in Ghana, the Burrito (Brachydeuterus auritus) and the flying gurnard (Dactylopterus volitans) were selected for study. Proximate composition analysis indicated high protein content (18-22%), an excellent amino acid profile with high levels of lysine (7-8%) as well as poly unsaturated fatty acids predominantly 20:5co3 and 22:6co3 (omega 3 fatty acids), which constituted between 44 and 51% of the total fatty acids. Sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis of the myofibrillar extracts showed that both fish species may be distinguished from each other by protein bands with molecular weights estimated to be 18,400 and 14,300 daltons. Rheological methods, differential scanning calorimetry (DSC), phase contrast microscopy and FT-Raman spectroscopy indicated a positive synergistic interaction between flying gurnard proteins and cowpea flour resulting in greater than expected elastic modulus values. The networks were compatible and stabilized by hydrophobic and hydrogen bonds as well as disulfide bonds. Optimum gels were formed with flying gurnard fish and cowpea flour mixed in the ratio of 5:5 (w/w) and Burrito fish mince to cowpea flour ratio (2:8 w/w). Interactions of the fish minces with cassava starch resulted in phase separation and weak non-covalent interactions. Infant weaning food formulations including flying gurnard mince and other food ingredients showed good nutritional and low viscous properties which compared favourably with commercial infant foods. The shelf life of the products was enhanced with the exclusion of oxygen in vacuum-packed foil packaging. High bloom (275 g) gelatin was produced from flying gurnard fish skin and compared favourably with gelatins from other sources. Using a low cost single screw food extruder built for developing countries, fish based extruded snack pellets incorporating minced burrito: cassava starch, were successfully developed at a barrel temperature of 120 °C. Extruded snack products stored in aluminium foil pouches were better protected in terms of chemical changes in free fatty acids and TBARS formation, than those packaged in polyethylene pouches. This development of fish-based extruded products will lead to new products of high nutritional quality and acceptability as shown by chemical and sensory evaluation results.

In the present study the effects of characteristic freezing times and storage time at -22°C on the quality of the adductor muscle of post-rigor scallops (Pecten maximus)and gilthead seabream fillets (Sparusa urata) were studied in regard to the integrity of muscle structure, myofibrillar protein denaturation and aggregation, lipid degradation, texture and sensory changes. This information would be useful for achieving optimal conditions for freezing these species and assessing their quality during frozen storage for commercial purposes. Scallop muscles and gilthead seabream fillets were frozen individually with characteristic freezing times that can be met in commercial practice of freezing seafoods. After freezing, the samples were thawed and their quality was evaluated. Fresh samples were analyzed as controls. Intermediate characteristic freezing times (i. e. 89 and 49 minutes for scallop muscles and 74 minutes for gilthead seabream fillets) caused more damage to cell structure of both species than the shorter and longer characteristic freezing times tested. Short characteristic freezing times (i. e. 19 minutes for scallop muscles, and 2 and 18 minutes for gilthead seabream fillets) reduced the thawing losses of both species compared to the longer characteristic freezing times (. e. 235 to 1000 minutes for scallop muscles, and 640 minutes for gilthead seabream fillets) tested. Freezing at short characteristic freezing times produced raw fillets similar in texture to the fresh fillets. Therefore, short characteristic freezing times (equal to or less than 19 minutes) are beneficial for freezing both species. Scallop muscles and gilthead seabream fillets were kept frozen for up to 301 and 340 days, respectively. Sampling was carried out at regular intervals on fresh and stored frozen samples. Storage time affected the integrity of infra-cellular organelles, reduced the water holding capacity, caused structural changes to myofibrillar proteins and affected the sensory attributes of both species. Frozen scallop muscles were in acceptable eating condition after a storage period of ten months, with most of the changes in bio-chemical and physical properties being pronounced after three months of storage. Based on the changes in taste scores versus storage time, it was assessed that the practical storage life of frozen gilthead seabream fillets was circa 5 to 6 months Cat+-ATPase activities for scallop muscles and a linear model that combines free fatty acids, peroxide values and protein content in centrifugal tissue fluids for gilthead seabream fillets, may be reliable methods for industry to use for assessing their quality during long term storage at -22°C.