The storage of red snapper (Lutjanus spp.) in ice, chilled sea water and chilled fresh water

The results are given of trials conducted to determine the effect on quality of holding fish (Lutjanus species) in chilled freshwater and also to compare the quality loss of fish stored in chilled seawater and chilled freshwater and in ice. No adverse effects were observed when storing in chilled freshwater apart from loss of external appearance after 6 days storage; taste panel tests showed acceptable conditions up to 15 days. Chilled seawater is unsuitable for storage as it spoils the intake of salt from the medium, making the flesh unpalatable.

Impact of dead and sunken water hyacinth on biotic communities, the aquatic environment and socio-economic activities

The mobile water hyacinth, which was produced in growth zones, especially Murchison Bay, was mainly exported to three sheltered storage bays (Thruston, Hannington and Waiya). Between 1996 and May 1998, the mobile form of water hyacinth occupied about 800 ha in Thruston Bay, 750 ha in Hannington Bay and 140 ha in Waiya Bay). Biological control weevils and other factors, including localised nutrient depletion, weakened the weed that was confined to the bays and it sunk around October 1998. The settling to the bottom of such huge quantities of organic matter its subsequent decomposition and the debris from this mass was likely to have environmental impacts on biotic communities (e.g. fish and invertebrate), physico-chemical conditions (water quality), and on socio-economic activities (e.g. at fish landings, water abstraction, and hydro-power generation points). Sunken water. hyacinth debris could also affect nutrient levels in the water column and lead to reduction in the content of dissolved oxygen. The changes in nutrient dynamics and oxygen levels could affect algal productivity, invertebrate composition and fish communities. Socio-economic impacts of dead sunken weed were expected from debris deposited along the shoreline especially at fish landings, water abstraction and hydropower generation points. Therefore, environmental impact assessment studies were carried out between 1998 and 2002 in selected representative zones of Lake Victoria to identify the effects of the sunken water hyacinth biomass

Changes in lipids of mussel during storage

Proximate composition, lipid and fatty acid components of dried mussel and changes in lipids during 1 year storage were studied. Male mussel contained lower fat contents and higher contents of polyunsaturated fatty acids of C20:5n-3, and C22:6n-3. High percentages of Cl6:1, Cl7:1, Cl8:3n-3, C20:3n-8 existed in NL and C!6:0, C18:0, Cl8:1n-9, C20:2n-6, C20:5n- 3, C22:6n-3 were very rich in PL. Triglycerides phosphatidylcholine, cholesterol were major components of mussel lipids. Free fatty acids (FFA) increased greatly and phospholipids decreased during storage, saturated fatty acids showed an increase trend and polyunsaturated fatty adds decreased differently. Dried mussels were vacuum packed and air packed and packaging methods had a great influence on the oxidation of mussellip,ids, indicating preference of vacuum packaging.

Minimize frequency fluctuations of isolated power system with wind farm by using superconducting magnetic energy storage

Wind power generation as one of the most popular renewable energy applications is absorbing more and more attention all over the world. However, output power fluctuations of wind farm due to random variations of wind speed can cause network frequency and voltage flicker in power systems. The power quality consequently declines, particularly in an isolated power system such as the power system in a remote community or a small island. This paper proposes an application of superconducting magnetic energy storage (SMES) to minimize output fluctuations of an isolated power system with wind farm. The isolated power system is fed by a diesel generator and a wind generator consisting of a wind turbine and squirrel cage induction machine. The control strategy is detailed and the proposed system is evaluated by simulation in Matlab/Simulink.

Suitability of sodium lactate as cryoprotectant and its effect on gel forming ability and protein denaturation of croaker fish surimi during frozen storage

The effect of sodium lactate is compared with sucrose + sorbitol + sodium tri-poly phosphate as cryoprotectant on gel forming ability & protein denaturation of croaker surimi during frozen storage at -20±2°C for 90 days was evaluated. The quality of Croaker surimi with 6% (w/v) sodium lactate was examined in terms of biochemical parameters of muscle protein, thaw drip, gel strength and calcium ATPase activity :.omparing with those of surimi added with sucrose/sorbitol & without additive as control. Both the cryoprotectants minimized the negative effects of frozen storage on physico-chemical traits of myofibrillar proteins which was evident from the biochemical and sensory parameters. The residual Ca2+ ATPase activity and gel strength of surimi with sodium lactate were higher than those of control throughout 90 days of storage. Ca2+ A TPase activity and gel strength found a high positive correlation. From the results, it was found that sodium lactate was equally effective in preservation of croaker muscle protein native structure during frozen storage as the sucrose/ sorbitol and also less sweet without any risk of maillard browning.

Shelf life of dried products from small indigenous fish species under various packing and storage conditions

The overall quality of five SIS products was found in good condition up to 2 months storage on the basis of organoleptic, biochemical and bacteriological characteristics and all the products was excellent in sealed packed condition up to 45 days of storage. However, quality of the products stored in open air atmospheric temperature was found excellent for first 15 days. In an average the initial moisture content was in the range of 13.5 to 15.0% with highest moisture content in puti and lowest in chapila. At the end of the 60 days the moisture content reached to the range of 18.5 to 19.0% which was more or less near the recommended limit of 16% for dried fishery products. The moisture content beyond the recommended limit as the storage period increased further and at the end of 90 days the moisture content increased to the range of 22.9 to 24% when organoleptically the product quality became very poor. The changes in the value of total volatile base nitrogen (TVB-N), peroxide value (PO), moisture and aerobic plate count (APC) of solar tunnel dried products in sealed polythene packages were investigated during 60 days of storage. There was little or no differences in TVB-N, PO and bacterial load of each species packed under various polythene density. The initial TVB-N values were in the range of 10.30 to 12.40 mg/100g of the samples. TVB-N value increased slowly up to the end of the storage period and was to in the range of 46.20 to 57.00 mg/1 00 g of sample. Initially the peroxide values (P.O.) were in the range of 6.54 to 8.40 m.eq./kg oil of the samples. During 60 days of storage, P.O. values increased slowly and at the end of the storage period these values reached to the range of 22.00 to 25.30meq./kg of sample. The initial APC was in the range 5.3xl04-7.3x104 CFU/g. The bacterial load increased slowly and at the end of the 60 days storage period reached to the range 6.6x106 - 8.6x107 CFT/g.

Effect of benzocaine on opercular movement and oxygen consumption in Channa punctatus (Bloch)

Effect of anaesthetization with benzocaine at the rate of 18.0 mg.1super(-1) on juveniles of Channa punctatus was observed using a cylindrical glass respirometer. Oxygen consumption and opercular movement were studied at 3h and 24h of anaesthetization. The oxygen consumption of control fish increased linearly from 0.183±0.029 to 0.481±0.034 mlO sub(2).h super(-1) with an increase in body weight from 1.45±0.18 to 6.12±0.11g and showed a reduction (p<0.001) of about 41% in 3h and 37% in 24h anaesthetization of Benzocaine. Similarly, the opercular movement of control fish ranging between 46±1 to 49±1min super(-1) came down to show a reduction (p<0.001) of 43% and 38% respectively in 3h and 24h anaesthetization. The information is useful in calculation of oxygen requirement of this species for live transportation and other experimental purpose.

Effect of sublethal concentration of artificial seawater on oxygen uptake and opercular frequency in an Indian major carp, Labeo rohita (Ham.)

The present study reports the effect of artificial seawater on oxygen uptake and opercular frequency in an Indian major carp, Labeo rohita. Whereas a control fish of 7.34 g average body weight consumed 1.538 ml O sub(2.) hˉ¹, the 24h and 96h exposed fish of the same body weight consumed 1.07 4 and 0.897 ml O sub(2.) hˉ¹, respectively. The oxygen uptake per unit body weight under controlled condition was 0.219 ml. gˉ¹. hˉ¹, whereas in 24h and 96h exposed fish, it was 0.152 and 0.124 ml. gˉ¹, hˉ¹, respectively. The change in opercular movement in 24h exposed fish was 7.67% higher, whereas in 96h exposed fish, it was 22.43% higher as compared to the control one. All changes are highly significant (p<0.001).

Short-term preservation of Brachionus calyciflorus: effects of storage on protein, lipid and carbohydrate contents

The short-term preservation of Brachionus calyciflorus for 45 days at three different temperatures (4, -4 and -20°C) led to decrease in protein, lipid and carbohydrate contents in all the three cases. However, the rate of deterioration was much higher at 4C than at -4 and -20°C. At 4C, protein, lipid and carbohydrate contents reduced by 76.78, 81.11 and 62.83%, respectively, and at -4°C, these were 27.94, 37.46 and 18.42%, respectively, whereas at -20°C, the deterioration was limited to 9.28, 16.44 and 11.35%, respectively, when compared with the control values. Thus, preservation at -20°C is comparatively better as it exerts limited effect on the protein, lipid and carbohydrate contents of B. calycijlorus.

Development of intermediate moisture marinated fish product and its storage characteristics

An attempt was made to prepare an intermediate moisture (around 44% moisture) marinated (pH around 4) fish product. Fillets from Sciaenid fish (each fish weighing 70-80 gm) were dipped in a solution containing 7% acetic acid, 20% common salt and 1% propionic acid for 2 hours. After soaking, the soaked fillets were partially dried to about 44% moisture. Three effective hurdles like low pH (by using 7% acetic add and 1% propionic acid), low water activity (by using 20% salt and partially drying the fillets) and preservative (1% propionic add), were used to prepare a shelf-stable product at room temperature. The dried product was sprayed with 0.0 5% BHA in 50% alcohol and further dried for 10 minutes to remove added water and alcohol, thereby another hurdle (preservative) against fat oxidation. The product was packed in 300 gauge polythene bags and stored in transparent screw cap plastic jars. Fortnightly samples were drawn and subjected to biochemical, bacteriological and organoleptic evaluation to study its storage characteristics. The product was in good acceptable form up to 4 months at ambient temperature. The product needed one hour soaking in water with two changes of water in between to make it free from excess salt and acid smell.

Studies on frozen storage characteristics of fillets from six species of fresh water fishes

Frozen storage characteristics of fillets from six major species of fresh water fishes namely, Labeo rohita, Catla catla, Cirrhina mrigala, Labeo calbasu, Mystus seenghala, and Wallago attu are reported. The biochemical, bacteriological and organoleptic changes in the frozen fillets during storage at -18°C have been followed systematically. Compared to the two species of fresh water cat fishes, the four species of carps studied, had a slightly better storage life. From the organoleptic point of view, fillets of Cirrhina mrigala had the best shelf life.

Ice storage characteristics of fresh and brined shark fillets

Ice storage characteristics of fresh and brined fillets from fresh shark (Carcharias melanopterus) were studied in and out of contact with ice for more than two weeks. Changes occurring in biochemical constituents, physical qualities and bacterial counts of the fillets are reported. Shelf life of brined fillets out of contact with ice was considerably longer than that of control samples tinder similar conditions. Icing of shark fillets is suggested as a method for the removal of urea on a commercial scale.

Lipid breakdown in oil sardine (Sardinella longiceps) during frozen storage

The problem of hydrolysis of lipids and consequent accumulation of free fatty acids and development of rancidity due to oxidation of the lipids are major problems in frozen storage of oil sardine (Sardinella longiceps). The course of the phospholipid breakdown, production of free fatty acids and the changes taking place in the major unsaturated fatty acids during frozen storage are described in this paper. The rate of free fatty acid production is faster in the fish, with the higher fat content. Unlike in lean fish, the neutral lipids are found to contribute substantially to the free fatty acid production. The fatty acids most affected during storage are C sub(20:5) and C sub(22:6). The polyene indices were found to decrease during storage. These effects are more pronounced in the fish with the higher fat content.

HACCP based management system for improving quality of freshwater giant prawn, Macrobrachium rosenbergii

The study was conducted on the present status of HACCP based quality management system of golda, Macrobrachium rosenbergii farms in Fulpur region of Mymensingh. Information was collected on general condition of farms, culture systems and post-harvest quality management. In almost all farms, there is no or inadequate infrastructure facilities such as, road access, electric supply, telecommunications, ice, feed storage facility, vehicle for golda transportation, washing and toilet facilities. The problems associated with sanitation and hygiene was: widespread use of cow dung, poultry manure and construction of open toilet within the vicinity of prawn culture pond. Different grades of commercially available and locally prepared feeds were used for golda culture in the pond. Golda post-larvae (PL) of 40-50 days old were stocked with carp species. The price of golda PL ranged from Tk. 1.00 to Tk. 1.25/piece. The pond size varied from 50 decimal (0.2 ha) to 2.5 acre (1.0 ha) with an average depth of 2-2.5 m. The culture period of golda varied from April-May to November-December and survival rate ranged between 75 and 80%. Production of golda varied from 250-500 kg/acre (625-1,250 kg/ha). Harvested golda were transported to city market within 4 h. Two size grading were generally followed during pricing, e.g. Tk. 500 to 550/kg for >100 g size and Tk. 300/kg for <100 g size. The cost-benefit ratio was found to remain around 1:1.25 depending on availability of PL. Water quality parameters such as, water temperature, pH, dissolved oxygen, total alkalinity and chlorophyll a in five golda farms in Fulpur region were monitored. Water temperature ranged from 29°C to 33°C, dissolved oxygen from 2.28 to 4.13 mg/l, pH between 6.65 and 7.94, alkalinity from 44 to 70 mg/l and chlorophyll a concentration from 61.88 to 102.34 µg/l in the five investigated ponds. The Aerobic Plate Count (APC) of the water sample was within the range of 2.0x10^6 - 2.96x10^7 CFU/ml and of soil samples within the range of 6.9x10^6 - 7.73x10^6 CFU/g. Streptococcus sp., Bacillus sp., Escherichia coli, Staphylococcus sp., Pseudomonas sp. and Salmonella sp. were isolated from pond water and sediment. Different feed samples used for golda was analyzed for proximate composition. Moisture content ranged around 14.14-21.22%, crude protein 20.55-44.1%, lipid 4.67-12.54% and ash 9.7-27.69%. The TVB-N values and peroxide values of feeds used as starter, grower and fish meal were found within the acceptable ranges and samples were free from pathogenic organisms. A training was organized for the golda farmers on HACCP, water quality and post-harvest quality management of prawn.