Value-added products from underutilized fish species

Fish is a rich source of easily digestible protein that also provides polyunsaturated fatty acids, vitamins, and minerals for human nutrition. Nonetheless, a large proportion of total landed fish remains unused due to inherent problems related to unattractive color, flavor, texture, small size, and high fat content. Most of these underutilized fish belong to the abundantly available pelagic species, which are landed as bycatch, and some are unconventional species such as krill. Although some species are used industrially for fish meal manufacture, a need for their conservation and utilization for human consumption has been recognized in order to prevent post-harvest fishery losses. Recovery of flesh by mechanical deboning and development of value-added products are probably the most promising approaches. This article discusses various possibilities for product development using mince from low-cost fishery resources. These include surimi and surimi-based products, sausages, fermented products, protein concentrates and hydrolysates, extruded products, and biotechnological possibilities. The dual advantages of this approach, namely, finding ways for better utilization of low-value fish species and providing protein- rich convenience foods, have been pointed out. However, the key to the success of this approach depends largely on the market strategies utilized.

Extracellular Proteases of Contaminant Bacteria in Fish Spoilage: A Review

Although the bacteriology of fish spoilage has been the subject of a number of reviews, the role of bacterial protease secretion in relation to fish spoilage has not received enough attention. This article attempts to focus the proteolytic activities of contaminant microorganisms in fish, the role of muscle constituents on protease synthesis, involvement of extracellular proteases in bacterial penetration of the muscle, and action of the enzymes on fish muscle proteins. The limitation of conventional chilling in completely controlling the bacterial spoilage has been stressed since the proteases secreted by psychrotrophic organisms can act on the fish muscle even at low temperatures. The article advocates employment of stringent measures to control secretion and activities of bacterial extracellular proteases to prolong the keeping qualities of refrigerated fish.

Stability of Radurized Indian Mackerel ( Rastrelliger kanagurta ) as a Function of Temperature

The influence of 1.5 kGy of gamma irradiation on the stability of Indian mackerel ( Rastrelliger kanagurta ) stored at temperatures of 0, 5, 10 and 15 C was examined. Using several indices for assessment of quality, it was found that the radiation treatment suppressed the rate of spoilage of fish stored at the above temperatures. However, the relative spoilage rates of both unirradiated and irradiated mackerel were similar as a function of storage temperature. The storage-life of fish calculated on the basis of the Spencer and Baines equation for evaluation of spoilage compared favorably with scores obtained by organoleptic evaluation.

Radionuclide scanning in the early diagnosis of Perthes' disease

A prospective survey was carried out on all cases of irritable hip presenting at the Royal Liverpool Children's Hospital over a period of one year. All children had a radioisotope scan of the hips and were then followed for one year by serial radiography. Five of the 50 children seen during the one year had areas of ischaemia in the capital femoral epiphysis demonstrated on the scan. all five developed radiological signs of Perthes' disease within sic months. The remaining 45 had radiographically normal hips at one year.

Osteochondritis dissecans of the talus: the natural history

An assessment of 10 patients with osteochondral lesions of the medial or lateral articular surface of the talar dome was based, first on subjective symptoms and second, on an analysis of weight-bearing anteroposterior and lateral X-rays of both ankles. The mean period of follow-up was 15 years 11 months (range 7 to 28 years). In 5 of the 6 patients treated conservatively, radiologic assessment showed that the lesion had failed to heal, but nevertheless in each instance the ankle joint was relatively asymptomatic. Talocrural osteoarthrosis developed in only 2 ankles and was considered to be an uncommon complication in those joints treated either conservatively or by excision of the osteochondral fragment.

Regulation of the arginine dihydrolase pathway in Clostridium sporogenes

Arginine deiminase activity was induced during the vegetative growth of Clostridium sporogenes. The enzyme was sensitive to catabolite repression. The other enzymes of the arginine dihydrolase pathway, namely, ornithine carbamoyl-transferase and carbamate kinase, did not show such variation.

Regulatory responses of arginine deiminase in whole cells of Clostridium sporogenes

Arginine deiminase (EC 3.5.3.6) has been shown to have regulatory properties. The activity was observed to be sigmoidal with respect to substrate concentrations. Addition of histidine to the system caused the abolition of sigmoidal responses. The regulatory properties of the enzyme as well as the desensitising action of histidine could also be demonstrated with whole cell suspensions. The pH of the system also seemed to influence modulations in the enzyme.

Extension of Shelf-Life of Indian Mackerel (Rastrelliger kanagurta) by Irradiation

A dose of 150 krad was optimum for extending refrigerated (0–2 C) shelf-life of fresh Indian mackerel (Rastrelliger kanagurta). This dose extended the shelf-life to 25–30 days from 10–12 days without inducing undesirable changes in the organoleptic qualities. Vacuum-packaging affected the appearance of the irradiated product by drawing out muscle fluids during storage. Samples irradiated aerobically did not become rancid and were acceptable to a taste panel. Storage of fish in ice beyond 5 days before irradiation reduced its post-irradiation shelf-life.