Structural Characteristics and Nutritional Composition of Two Marine Fish Species (Rastrelliger kanagurta and Chrysochir aureus) of Bangladesh

Abstract

The post-harvest processing and storage of fish are affected by nutritional composition of their body. The optimal techniques of variable species to specific processing and storage techniques could be determined by knowing proximate composition of fish. The research concentrated on muscle structure with identifying myotomes, processing yields, chemical composition of various muscle types, proximate composition of distinct body sections and gel strength of Indian Mackerel (Rastrelliger kanagurta) and Reeve’s Croaker (Chrysochir aureus) fish muscles. The fishes were sourced from the Bay of Bengal. Fresh fish samples were taken from the fishing vessels at Teknaf and frozen at -20°C, and transported to the CVASU laboratory for further investigation. The findings revealed that Rastrelliger kanagurta had a muscle yield of 46.98%, which included 89.82% white muscle and 10.18% dark muscle with 26.88% carcass and viscera of total body weight. In contrast, Chrysochir aureus had a muscle yield of 40.33%, comprising 93.79% white muscle and 6.20% dark muscle with 27.93% carcass and viscera of total body weight. Both fish species had the greatest protein concentration in white muscle, but dark muscle displayed increased lipid levels, notably in the midsection and tail regions, resulting in raised lipid content. The head region of both fish species showed the highest moisture level and the lowest level of protein content. Both fishes showed high amount of ash content in mixed muscle particularly in tail region of fish body. Gel strength was tested at variable heating settings (40°C, 50°C, and 60°C) for 2 hours in a water bath for both fish samples. The optimal gel-forming temperatures were found to be 50°C and 40°C for Chrysochir aureus and Rastrelliger kanagurta which had been showed 411.46 ± 1.81 g.cm and 457.34 ± 1.59 g.cm gel strength. These findings of the research demonstrate that both fish species are not only appropriate for consumption but also for the development of value-added fish products.