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20014
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Subject: Fisheries × End date: 2002 × Start date: 2001 × Type: Thesis × Thesis Type: M.Sc ×
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    ThesisItemOpen Access
    Development of Malaysian Type Fish Crackers From Nemipterus Japonicus (BLOCH)
    (Department of Processing Technology,College of Fisheries, Panangad, 2001) Venugopal, Dubakula; KAU; Sajan, George
    A study was undertaken for the preparation of fish crackers using a low cost fish, threadfm bream (Nemipterus japonicus, Bloch). A method was standardised for making crackers based on that generally followed in Malaysia. Fish meat was mixed with various food additives such as starch, salt, sugar, monosodium glutamate, colour and water, and stuffed into high-density polyethylene casings as rolls, cooked, cooled, sliced and dried.
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    ThesisItemOpen Access
    Role of putative male pheromoneiIn the ovarin maturation of the fresh water prawn Macrobrachium Idella (Hilgendorf)
    (Department of Fishery Biology, College of Fisheries, Panangad, 2001) Patil Chandrakant, Sitaram; KAU; Jose, T M
    Sex pheromones are reported to be present in many crustaceans which mostly have releaser effect on sexual behaviour. The discovery of a male (primer) pheromone with stimulatory effect on ovarian maturation and ovulation has added an important external factor to the basic mechanisms regulating reproduction in fresh water prawns. But studies in these lines are very few in the economically important species of Macrobrachium. Knowledge about this male pheromone will be useful to help or potentiate reproduction and/or extend the breeding period of freshwater prawns, which are of great aquacuItural importance. The present study was carried out in the slender nver prawn, Macrobrachium idella. Seven ovarian maturity stages have been distinguished here. Histological studies of the maturing oocytes helped to understand the changes taking place during oocyte growth and maturation through the progressive maturity stages. Yolk vesicles start appearing in the cytoplasm of oocyte in maturity stage II which is the beginning of vitellogeneis (vitellogenesis I). In stage IV, yolk platelet synthesis starts and 'a peripheral layer of yolk platelets appear in this stage. Later these yolk platelets completely fill the ooplasm through stages V and VI when the ova increase in size enormously. Gonado- somatic index (ovarian index) of different maturity stages was determined and was found useful to differentiate especially the late maturity stages. Ova diameter studies along with the other observations showed a clear picture of protracted multiple spawning in this species with batches of ova undergoing maturation and ovulation in successive maturation cycles. When the females were reared in isolated condition, their ovarian growth was found to be arrested at early stage IV. This restriction of ovarian maturation was found mostly in the second maturation (gonadal) cycle after isolation. But those isolated females which had a common water circulation with males showed normal ovarian maturation and ovulation. Therefore, it can be concluded that a male pheromone exists in this species which is essential for normal ovarian growth and maturation. Another experiment was conducted to find out the tissue source of this putative male pheromone. When these isolated females were exposed to extracts of testis, vas deferens or muscle, both testis and vas deferens extracts were found to stimulate the ovarian maturation and ovulation in isolated females, while the muscle extract (control) was ineffective. This shows that in M idella, the male pheromone is produced by testis and vas deferens or it is produced by testis and transported to vas deferens. Further experiment showed that charcoal extraction destroys the pheromonal activity in testis and vas deferens extract while boiling has no such effect which indicates that the ovary stimulating pehromone in M idella may be a steroidal molecule as reported in some fishes.
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    ThesisItemOpen Access
    Evaluation of protein requirement of angel fish [Pterophyllum scalare (Lichtenstein)] larvae using defatted clam meat as the chief protein source
    (Department of Aquaculture, College of Fisheries, Panangad, 2001) Deepa Viswanath, K; KAU; Mohan, M V
    The effect of artificial diets with varying protein levels on the growth and survival of Angel fish, Pterophyllum scalare (Lichtenstein) larvae using defatted clam meat powder as the chief protein source was studied. One-day-old free-swimming hatchlings were used in the investigations done for a period of 21 days. The different diets used were with 24.91 %, 29.83%, 34.72%, 39.86%, 44.79%,49.85% and 54.63% protein levels with 3 replicates for each treatment. The results showed that the growth of larvae in terms of gain in length, gain in weight and specific growth rate was maximum for the diet with 44.79% protein level. From the relationship established between protein level and SGR, the optimum level of protein attaining maximum SGR (21.163) was found to be 53.099%. No significant difference was found in the survival rate of larvae fed with different diets. Thus artificial diet with 44.79% protein level can be used efficiently for rearing Angel fish larvae.
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    ThesisItemOpen Access
    Cause of yellow discolouration in iced and frozen cuttlefish fillets and its control
    (Department of Processing Technology, College of Fisheries, Panangad, 2001) Sophia Margaret Joseph; KAU; Sherief, P M  
    The cause of yellow discolouration in ice stored and subsequently frozen cuttlefish fillets of Sepia aculeata was investigated in this study. The fillets were subjected to the following treatments (l) control (2) dip in 2% salt + 0.2% citric acid solution for 10 min. and (3) dip in 0.01% BHA solution for 10 min., prior to ice storage for a duration of six days. The iced fillets were frozen on the zero day, second day and fourth day of iced storage. Both the iced and frozen samples were periodically subjected to various biochemical and sensory evaluations. The NPN and alpha amino nitrogen contents of the salt + citric acid samples, both in the iced and the frozen samples, were found to be higher than those of the other two. This suggests that salt + citric acid are capable of retaining moisture and preventing the leaching of NPN compounds. This is supported by the sensory evaluation results, which gave higher scores~lt + citric acid treatment. The increase A in TVBN and TMA contents were found to be less pronounced in the salt + citric acid treated samples suggesting the microbial and enzyme inhibitory action of the salt and citric acid. The increase in the PV and TBARS were also less in this treatment when compared to the control, showing antioxidant property of citric acid. The BHA treated samples showed the least rise in PV and TBARS both in iced and frozen material, indicating its effectiveness as an antioxidant. . Sensory evaluation of the iced samples showed no discolouration during the period of six days, but the fourth day frozen untreated samples showed yellow discolouration after the eight weeks of storage. Since the salt + citric treatment and BHA treatment are effective in retarding the yellow discolouration, a Maillard or an 149 aldehyde amine type reaction is postulated as the possible cause of yellow discolouration in frozen stored cuttlefish. As the proteolytic activity at the site of appearance of yellow discolouration was high, the amino compounds formed by the enzyme action may be taking part in the aldehyde - amine reaction, the aldehyde being produced by autoxidation of the unsaturated phospholipids of the meat.