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Publication History View all

  • School of Industrial Fisheries, Cochin University of Science and Technology, 01/2010, Degree: MSc. Industrial FIsheries, Supervisor: Prof. Dr. K T Thomson
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    ABSTRACT: The effect of natural sunlight on four polyamide monofilament yarns and four polyamide multifilament twines was studied. The samples, each of different RTex were exposed to 180 days solar radiation and sub-samples were drawn at intervals to study the effect on breaking strength and elongation at break. Significant reduction in both breaking strength (P < 0.01) and elongation at break (P < 0.01) have been recorded in the test samples due to weathering. Breaking strength reduced linearly with the period of exposure, while no such linear relationship was found in the case of elongation at break.
    Fisheries Research 11/2006;
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    ABSTRACT: The characteristics and stability of natural actomyosin (NAM) from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) were investigated. The total extractable actomyosin (AM) was higher (7.60 mg ml −1) in the case of rohu compared with that from catla and mrigal (5 mg ml −1). Although the specific AM ATPase activity was similar (0.43–0.5 µmol P min −1 mg P −1) among the three species, the total ATPase activity was lower in mrigal (25 µmol g −1 meat) compared with the other species (37 µmol g −1 meat). The inactivation rate constants (k d) of AM Ca ATPase activity showed differences in the stabilities of actomyosin among these fish, the actomyosin from catla being least stable. The NAM from these species was stable up to 20 • C at pH 7.0. Catla AM became unstable at 30 • C, while rohu and mrigal AM could withstand up to 45 • C. The thermal denaturation with respect to solubility, turbidity, ATPase activity, sulphhydryl group and surface hydrophobicity showed noticeable changes at around these temperatures.  2004 Society of Chemical Industry INTRODUCTION Among the freshwater fish produced in India, the major carp of India—rohu, catla and mri-gal–predominate, with a market share of over 90%. These fish are usually consumed fresh. They are sold fresh direct from the farm, or iced and transported to internal markets. During July to September every year when marine fishing is banned, there is strong demand for these fish, but in other seasons they do not fetch a good return for the producers. There are suggestions to use these fish for the production of surimi and other value-added products. Fish muscle myofibrillar proteins are relatively unstable. 1 The functional properties of protein are directly related to the quality of myofibrillar protein 2,3 and the properties of myofibrillar protein determine the quality of mince-based products. 4 Aggregation and denaturation of myofibrillar protein occur during frozen storage, affecting the texture, 5 – 7 as well as the gel-forming characteristics of the mince. 8 – 11 The stability of fish myofibrillar protein is species-dependent 12,13 and there is evidence relating the stability of actomyosin to the habitat temperature. 14,15 There are other constituents in the meat, such as free fatty acids, 16 free amino acids and nucleotides, 17 that affect the stability of protein during frozen storage. Protein denaturation involves the formation of intermolecular aggregates through hydrogen, hydrophobic 18,19 and disulphide bonds, 20 making denaturation an irreversible process. Changes in turbidity and light scattering, 21,22 solubility 23 and ATPase activity 24 – 26 have been reported during protein denaturation. The aim of this study was to investigate the stability and properties of natural actomyosin (NAM) from three major freshwater carp of India, ie rohu, catla and mrigal, and to provide information for the storage and processing of these fish.
    Journal of the Science of Food and Agriculture J Sci Food Agric. 01/2005; 85:563-568.
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    ABSTRACT: The effects of varying dietary protein level (200, 250, 300 and 350 g protein kg−1 diet) and plant : animal protein ratio (1 : 2, 1 : 1, 1 : 1.5 and 2 : 1) on growth of juvenile Macrobrachium rosenbergii (de Man) with approximately 0.27 g initial body weight were evaluated in two separate 30-days study using practical diets. Significantly lower survival rate was recorded in prawns fed a diet containing 200 g kg−1 dietary protein (66.67%) whilst 300 and 350 g kg−1 protein gave the highest survival (96.67%). Significant differences (P < 0.05) in feed conversion ratio and protein efficiency ratio were recorded among different dietary protein levels. The results of the study showed that highest growth rate and maximum utilization of protein were recorded in prawns fed 300 g kg−1 dietary protein and further increase in the dietary protein does not have any added advantage. There existed no statistically significant difference (P > 0.05) in the specific growth rate, protein efficiency ratio, weight gain and survival rate among the juveniles of M. rosenbergii fed varying plant–animal protein ratios at 300 g kg−1 protein. Better-feed conversion ratio was recorded in diets having a plant to animal protein ratio of 1 : 1 (2.62) followed by 1 : 1.5 (2.66), however there was no significant difference between them (P > 0.05). Based on the present study, it would be possible to replace animal protein by low-cost plant protein in prawn feed. Better growth performance in juveniles of M. rosenbergii can be achieved by the incorporation of equal proportions of plant and animal protein (A : P = 1) in the diet.
    Aquaculture Nutrition 03/2003; 9(2):131 - 137.
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    ABSTRACT: Two sets of adaptive trials were performed to determine the effects of size grading and batch grading on size heterogeneity in cultured Macrobrachium rosenbergii raised in the Coconut Garden channels of Kuttanad, Southern India. In the first set of trials, postlarvae were batch graded on the basis of their hatching order, segregated and grown separately as first-hatched and second-hatched groups. In the second set of trials, postlarvae were size graded as jumpers and laggards and were grown in separate channels. The average weight attained by prawns after 10 months of culture was highest for jumpers (83.11 g) and lowest for the prawns from the first-hatched group (43.76 g). The percentage of males was highest in the population of jumpers (58.23%). Highest production was recorded in the channel stocked with postlarvae from the second-hatched group (103.4 kg ha−1) and lowest production was obtained from the first-hatched group (63.74 kg ha−1). The proportions of undesirable small males were highest among laggards and the first-hatched group: 24.8% and 15.1% respectively. The level of heterozygosity within morphotypes was also high in these groups. Jumpers attained good growth by the end of culture but, because of their low survival rate, this approach was not economically feasible. However, higher production and survival in the second-hatched group improved economic viability. Thus, for better results, stocking with later-hatched groups would be more appropriate than stocking with the first-hatched group.
    Aquaculture Research 12/2002; 33(15):1221 - 1231.
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    ABSTRACT: The gel strength, compressibility and folding characteristic of suwari (set) and kamaboko (set and cooked) gels prepared from rohu (Labeo rohita), catla (Catla catla) and mrigal (Cirrhinus mrigala) surimi were examined to understand the occurrence of suwari and modori phenomena in surimi from major freshwater carps. Suwari setting of gels did not take place at lower temperatures. Suwari gels showed good gel strength at 50 °C for rohu and at 60 °C for catla and mrigal after 30 min setting time. Incubation for 60 min decreased the gel strength at 60 °C for rohu and catla. Setting at 25 °C followed by cooking at 90 °C increased the gel strength. Increased setting temperature, however, decreased the gel strength of cooked gels. Gel strength and compressibility data were supported by folding characteristics.© 2002 Society of Chemical Industry
    Journal of the Science of Food and Agriculture 06/2002; 82(9):1021 - 1027.
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    ABSTRACT: Hepatosomatic indices and biochemical profile of the male morphotypes of Macrobrachium rosembergii such as small males, weak orange clawed males, strong orange clawed males, pre-transforming strong orange clawed males, weak blue clawed males, strong blue clawed males of grow-outs and old blue clawed males from the Vembanad lake were studied. Size characterization of M. rosenbergii agreed with the earlier reports. A marked variation in hepatosomatic index (HSI) of morphotypes indicated the possibility of differences in food assimilation and growth rates. Mean HSI values were highest in strong orange clawed males (6.351) and lowest in small males (2.814). Among the various biochemical components of male morphotypes studied, protein, RNA and DNA in muscle tissue as well as carbohydrate and RNA in hepatopancreas showed significant differences. Faster somatic growth observed in strong orange clawed males can be correlated with the higher values of protein, DNA and RNA recorded in the muscle tissue as well as high HSI, carbohydrate and RNA contents of hepatopancreas. The results of the present study reveal that there exists perceptible variations in HSI and biochemical profiles among the male morphotypes of M. rosenbergii.
    Aquaculture 01/1999; 176(3):285-293.
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    ABSTRACT: Gill netting provide important advantages over many other fishing methods in a multispecies fishery. However, the simultaneous use of many small mesh sizes in the inshore waters needs monitoring. Landing data from small mesh gill nets of 30, 32, 34, 36, 38, 40, 48, 50 and 52 mm were collected for two years from canoes operating off Cochin. Seasonal usage of different mesh sizes, spe-cies composition, size composition and proportion of juveniles in the catch are discussed. A total of 38 species of fishes were caught pointing out the difficulty in managing the tropical multispecies fishery. Of the different mesh sizes used, 30 and 32 mm are to be used with restraint, as proportion of juveniles caught in these were substantial. This would render gill netting a more ecofriendly fish-ing method for the inshore waters.
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