Organoleptic, biochemical and bacteriological aspects of five tropical marine fish such as silver jewfish, Bombay duck, big-eye tuna, Chinese pomfret and ribbon fish stored in ice were studied. Organoleptically all fish were found acceptable for 10-13 days before becoming inedible. Proximate analysis showed that moisture content increased slightly; protein and lipid content decreased gradually and ash had little or no significant change. pH, TVB-N, peroxide and aerobic plate count values increased with increasing storage period but the values were within acceptable range up to 10 days of storage. Changes in myofibrillar ATPase activity and solubility of these fishes showed that Ca 2+ ATPase in the presence of both 0.1 m and 0.5 m KCl decreased gradually whereas no marked changes were observed in the Mg +2 ATPase activities in the presence ⁄ absence of Ca +2 . Myofibrillar protein solubility of all fish samples also decreased considerably during ice storage. The decrement in Ca 2+ ATPase activity and solubility indicates denaturation of myofibrillar protein of fish samples during ice storage.

Studies were conducted to optimize fish‐drying process in a Hohenheim‐type solar tunnel dryer to produce safe and high quality dried fish products. Five commercially important tropical marine fish species in the Bay of Bengal such as silver jew fish, Bombay duck, big‐eye tuna, Chinese pomfret and ribbon fish were used and drying was performed at 45 to 50 and 50 to 55C temperature ranges. Moisture content of the fish samples reached 16% after 36 and 32 h of drying at temperature ranges of 45 to 50 and 50 to 55C, respectively. Products produced at 45 to 50C were found to be excellent on the basis of flavor, color and texture. Their rehydration ability ranged from 65 to 80% with minimum in big‐eye tuna and maximum in silver jew fish. Values of total volatile base, peroxide and aerobic plate count of all the final dried products were within the acceptable limit. PRACTICAL APPLICATIONS In this experiment, we optimized the drying process in a Hohenheim‐type solar tunnel dryer, constructed using locally available materials, for several commercially important marine fish species in the Bay of Bengal over a wide range of temperature, humidity and moisture content. The data obtained in this study are now successfully used for large‐scale production of dried fish of high quality, providing better market price for its producers as well as greater acceptability to the consumers. We also developed another low cost solar tunnel dryer using bamboo, hemp, canvas, rope and polythene sheets, which became very popular among small‐scale dry fish producers in the coastal areas of Bangladesh.

No abstract

Sequence analyses of mitochondrial (mt) and nuclear genes were performed for genetic comparison between two Takifugu pufferfish species: torafugu T. rubripes and karasu T. chinensis. With a sequence coverage of 20% in mtDNA, 640, 308, 344, 522 and 697 bp encoding mt 16S ribosomal RNA (rRNA), adenosine triphosphatase 6 (ATPase 6), nicotinamide adenine dinucleotide dehydrogenase subunit 4 (ND4), ND5 and cytochrome b (cyt b), respectively, among 24 wild torafugu, 24 wild karasu and six hybrid-like samples, 15% of the torafugu identified by external color patterns showed nucleotide sequences consistent with karasu. Meanwhile, sequences of 60% karasu were consistent with those registered for torafugu (AJ421455). As for the hybrid-like samples, two possessed karasu-specific sequences in some base positions while torafugu-specific sequences in others. The remaining hybrid-like samples possessed torafugu-specific sequences. On the other hand, the mt control region did not show such type of consistency. Analysis of nuclear melanocortin receptor genes (MC1R, MC4R) among 54 samples showed 99-100% inter-and intraspecific sequence identity. Partial nuclear 18S rRNA, complete internal transcribed spacer 1 (ITS1), partial 5.8S rRNA and ITS2 genes showed similar levels of identity, indicating a very low level of variation in their respective gene fragments between the two Takifugu species.

Sun drying of fish is an important method of fish preservation throughout the world. Due to its availability and product specific flavor and texture, dried fish has become an important part in the diet of people living particularly in the coastal region of many Asian countries including Bangladesh. Product type is considerably wide depending on the season, availability of fish, infrastructure and technical know-how of the processors. These are mainly processed from marine fishes that are caught by the artisanal fishermen and marketed throughout the country by multistep marketing channel up to reaching to the consumer. Due to the importance of the product in terms of market volume as well as its major role in the socio-economic condition of millions of people of the country, the sector needs proper attention by appropriate authorities to ensure quality and safety of the product produced and marketed. In this paper, different methods of sun drying practiced traditionally in the coastal region of Bangladesh and associated marketing systems are reviewed. It is expected that training of processors on Sanitation Standard Operating Procedures and monitoring by appropriate government body would be necessary to improve quality and simultaneously ensure safety of sun-dried fish produced in the coastal region of Bangladesh. Res. Agric., Livest. Fish.5(3): 381-390, December 2018