Methods of sensory evaluation of quality and application of statistical methods in sensory evaluation problems with special reference to fishery products

The quality of raw and processed fishery products depend on several factors like physiological conditions at the time of capture, morphological differences, rigor mortis, species, rate of icing and subsequent storage conditions. Sensory evaluation is still the most reliable method for evaluation of the freshness of raw processed fishery products. Sophisticated methods like Intelectron fish tester, cell fragility technique and chemical and bacteriological methods like estimation of trimethylamine, hypoxanthine, carbonyl compounds, volatile acid and total bacterial count have no doubt been developed for accessing the spoilage in fish products.

Freeze drying of fishery products: Part IV - Biochemical changes occurring in prawn muscle during freezing, freeze drying and prolonged storage of the freeze dried product

The changes occurring in water and salt extractable protein and non-protein fractions in prawn muscle of different species during freezing, freeze drying and subsequent prolonged storage have been studied. There is no denaturation of water extractable proteins, whereas salt extractable proteins were rendered insoluble to the extent of 21% due to freeze drying. The freeze dried products remained in good edible condition for 32 months of storage up to which storage characteristics were followed.

Freeze drying of fishery products: Part V - Storage characteristics of ready-to-serve freeze dried foods

Behaviour of freeze dried ready-to-serve fish based food preparations during prolonged storage at room temp has been studied and reported in this paper. Storage life of such products under the conditions employed in this study can be reckoned in years at our ambient temps.

Purse-seines off Goa

The design, construction and operational details of the purse-seines operated from Goa, for sardines and mackerel are reported briefly. The deck equipment and details of vessel along with the fishing season, fishing grounds and catches are briefly accounted. The design has been compared with Japanese purse-seines operated for the same species of fishes. Based on the findings an improved design of purse-seine has been presented.

Studies on smoke curing of tropical fishes

Fresh mackerel (Rastrelliger kanagurta), catfish (Tachisurus dussumeri) and sole (Cynoglossus dubis) were gutted, cleaned, washed, brined, and smoked. Though it contributes to the quality of the smoked products, salt does not appear to prevent bacterial growth or spoilage at low concentration. In heavily salted products, salt is found to have a definite preservative action. Smoking lasted roughly 5 hrs for mackerel and 4 hrs for sole. Increasing the smoking time gave the product an unpleasant taste. Fish were then sun-dried to 20% moisture. The fish had been prepared in three groups, (1) turmeric-treated, (2) propionate-treated and control. Turmeric treated samples had a very attractive appearance, especially sole. The course of spoilage, as measured by following changes in total volatile nitrogen content, is tabulated. All controls were spoiled within 3 months; the others remained in good condition for 6 months. Turmeric is considered to be an ideal preservative.

Studies on preservation of fish in refrigerated sea-water

Storage characteristics of oil sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta) and seer (Scomberomorus guttatus) in refrigerated sea-water (RSW) were studied in comparison with their storage in crushed ice. Oil sardine stored in RSW was found to be comparable to iced ones only during the initial stages (up to 2 days) of storage and on further storage the former was found to be inferior to the latter. RSW can be advantageously employed for preservation of mackerel and seer. Mackerel and seer could be stored in RSW in acceptable condition for 4 to 6 days and 12 to 14 days respectively.

Investigations on long distance transportation of fish 1. Transportation of frozen fish from Cochin to Calcutta

Oil Sardine (Sardinella longiceps), mackerel (Rastrelliger kanagurta), cat fish (Arius sp.), threadfin bream (Nemipterus japonicus) and ribbon fish (Trichurus sp.) were frozen in glazed/unglazed blocks, packed in expanded polystyrene (EPS) insulated plywood boxes with and without additional ice and despatched in uninsulated parcel vans of trains from Cochin to Calcutta. The consignments reached the destination in excellent condition and were readily disposed off.

Further studies on changes in protein fractions of fish muscle during storage in ice

The changes in the major protein nitrogen fractions of two commercially important fishes of Indian waters, viz., mackerel (Rastrelliger kanagurta) and lactarius (Lactarius lactarius), during storage in ice are reported. The significance of the findings is discussed in comparison with the results of a similar study on two species of marine prawns and oil sardine, reported earlier.

The influence of plating technique and incubation temperature on bacterial count from fish and fishery products

For bacterial sampling of raw unprocessed fish and frozen fishery products, spread plate method is preferable to pour plate method; incubation of plates at 30°C gives a higher count than incubation at 37°C. Analysis of variance of the data shows that sample variation between different types of fishes is highly significant whereas the variations between triplicate plates are not significant at 5 % level.

Comparative study of the nutrient content of fish and shell fish

The amino acid, mineral and proximate composition of mullet (Mugil oeur), mackerel (Rastrelliger kanagurta), crab (Scylla serrata) and prawn (Penaeus indicus) are reported. The data are used for comparing the nutritional quality of the fish and shell fish. Further, the amino acid composition is screened for their adequacy to meet the FAO/WHO recommended pattern of essential amino acids.

Ecology of Indian estuaries-XI. A preliminary survey of the fishery resources of the Ashtamudi estuarine system

The fish fauna of the Ashtamudi, the second largest estuarine system in Kerala (8°53'-9°02' N Lat. and 76°31'-76°41' E Long.) is listed. 97 species belonging to 39 families have been recorded, ofwhich69 are commercially important contributing to the fisheries of the Ashtamudi Estuary. Mullets, cichlids and the glassy perchlets are the most abundant groups and contribute appreciably to the landings. Results revealed that the estuarine system supports a good capture fishery which is seasonal. Majority of the fish fauna in the estuary are marine elements recruited from the adjoining Arabian Sea. An inventory of the craft and gear employed is presented and the sources of pollution in the estuarine system are described, aquacultural prospects of this area are discussed.

Quality of cured fishery products from Malabar and Kanara coasts

Results of chemical, bacteriological and organoleptic quality studies of cured fishery products of commerce collected from six major fish curing centres on the west coast of India are presented. 77.12% of the samples had moisture above 35%, 97.18% showed salt content below 25% and all samples had acid insoluble ash above 1.5%. 42.32% gave standard plate counts above 10,000 and 45.77% were contaminated with 'Red' halophiles. The major defects in curing were imperfect cleaning, inadequate salting and unhygienic conditions of processing.

Temporal behaviour of marine landings along coastal Karnataka 1. Relative distribution and secular trends

Landing data of 21 fisheries from Karnataka (quarterly landings for the period 1956 to 1978 and annual landings for the period 1979 to 1981) were analysed to study the te111poral behaviour of the landings. The relative distribution and secular trends in each of the fisheries are reported. On an average, mackerel and oil sardine together account for about 70% of the annual landings. The fluctuation in the landings in all the fisheries was very high with the coefficient of variation attaining a minimum value of 61.53%. The inverse relationship between the landings of oil sardine and mackerel was found to be statistically significant. It is suggested that fishing effort be further increased in fisheries that have demonstrated a rising trend (about 73% of the total annual landings) as also in the case of the fisheries whose trends appear stagnant (about 21% of the annual landings). However, there seems to be some evidence of a need for regulating fishing in Hemirhamphus and Belone, Caranx and penaeid prawns. Regulations need to be made authentic with the help of sufficient information on not merely the fishery but on the whole population.

Selection of suitable diluents for bacteriological examination of fishery products

For raw, iced and frozen samples of fish and prawn, significant difference was observed in total plate counts done with various diluents, the significance level ranging from 5% to 0.1%. For raw fish, N-saline, seawater and quarter strength Ringers' solution gave maximum total plate counts. In the case of iced-fish, n-saline yielded highest total plate counts. For frozen samples, however, peptone water and n-saline gave good recoveries. Trials with suitable combinations of diluents showed that though some of them were as good as the control, namely n-saline, none were superior in any way.

Antibiotic sensitivity of Staphylococcus aureus strains isolated from fishery products

During the course of an investigation on the incidence of Staphylococcus aureus contamination in frozen crab meat, frozen prawns and dried fishes from Cochin, 116 strains of S. aureus were isolated. The sensitivity of the isolated strains towards nine antibiotics showed that all the S. aureus strains were sensitive to kanamycin and streptomycin (100%). Sensitivity to other antibiotics like chloramphenicol, polymyxin-B, erythromycin, tetracycline, neomycin, penicillin and ampicillin were shown by 98.28, 93.10, 87.93, 68.10, 67.24, 56.90 and 55.17 percent of the isolates respectively.