Refrigerated Sea Water Research Articles

Effects of Onboard Refrigerated Seawater Storage of Whole Ungutted Atlantic Cod (Gadus morhua) on Quality Parameters of Fillets

ABSTRACT The study aimed to evaluate the effects of onboard refrigerated seawater (RSW) storage of whole ungutted cod on the quality parameters of fillets. The reference group was directly gutted, bled, and stored in ice, while three experimental groups were gill-cut, bled, and stored ungutted in an onboard RSW tub at −1.5°C for 24, 60, and 84 hours. The results showed a difference between groups with extended RSW storage leading to negative effects such as increased gaping, bile spots, TVB-N levels, and bacterial growth after 60 hours. Conversely, the 24-hour RSW group closely resembled the quality parameters of the reference group.

Наливные рыболовные суда - новый тренд на промысле минтая у южных Курильских островов

The intensive development of fish processing factories built on the southern Kuril Islands stimulated the use of fishing vessels with RSW (Refrigerated Sea Water) storage tanks to deliver catches to coastal factories. At the moment, 8 fishing RSW-trawlers are operating in the southern Kuriles area. The capacity of RSW tanks on them varies from 500 to 2200 tons with a total one-time storage volume of 8 thousand tons. The main object of the fishery is walleye pollock. The walleye pollock catch by RSW-trawlers in 2022 reached 112 thousand tons. The main pollock harvesting area is the waters of the southern Kuril Islands, where about 70% of the total allowable catch (TAC) of this species is caught by RSW-trawlers. Compared to traditional trawlers-processor, RSW-trawlers fishering is more rational and “transparent” in relation to resources, because it exclude the possibility of discarding juveniles and substandard fish. It is assumed that the trend towards the use of RSW-trawlers in the Far East fishery basin will increase.

Examination of the potential of refrigerated seawater to improve live transport of the mussel Perna canaliculus: Physiological responses, meat quality and safety implications under different chilled storage conditions

Refrigerated seawater (RSW) based systems for post-harvest storage of green-lipped mussels (Perna canaliculus; also known as Greenshell™ mussels) were assessed. Two post-harvest storage trials were conducted in October 2020 and March 2021 (austral spring and summer respectively) on mussels recovered for 2.5 days after harvest in flow-through seawater. The mussels were randomly assigned to three post-harvest treatments, all conducted at 6.5 °C for 10 days: Chilled in air; immersion in recirculated RSW; and Periodic immersion in RSW (6 min h−1). A range of physiological, morphometric and quality measures were screened to assess their ability to indicate mussel performance. Further to this, mussels in duplicate systems were inoculated with Escherichia coli and Vibrio parahaemolyticus to inform on risks associated with pathogen proliferation. The mussels interacted with the seawater in both the RSW and Periodic RSW systems as seawater ammonia concentrations increased in both. Mussel mortalities counted across the 10-day trials were highest in the Chilled treatment (5.5%), followed by RSW (3.5%) and Periodic RSW (2.4%). Key measurements including haemolymph pH and osmolality, meat and intra-valvular water weight, and textural hardness, were all affected by the post-harvest treatments. For inoculated mussels, E. coli and V. parahaemolyticus most probable numbers (MPN) remained stable in both the Chilled and Periodic RSW treatments with reductions in both bacteria recorded in the RSW treatment. Higher variances in intra-valvular water retention and haemolymph haemocyte numbers and differences in volatile organic compound profiles were seen in the summer mussels, as compared with spring, highlighting mussel condition as a determining factor for post-harvest performance. RSW has therefore been demonstrated to be beneficial, but optimisation (e.g., through further reduction of metabolic activity) may further increase practical post-harvest transport distances and the quality of live/fresh mussel products.

Feasibility assessment of a CO2 based power, cooling, and heating system driven by exhaust gas from ocean-going fishing vessel

The research presents a novel CO2 transcritical trigeneration system for ocean-going fishing vessel. Cascade ejectors are employed to decrease the exergy destruction caused by the dual evaporators, enhancing the cooling capacity of the system. By recovering the waste heat of exhaust, the system is designed to cover refrigeration demand of a refrigerated sea water (RSW) tank, the domestic hot water demand at different temperature levels onboard, as well as the power for sailing. The performance of the system is investigated from both thermodynamic and economic perspectives. The feasibility of applying the proposed system to replace the original refrigeration system of a RSW tank is evaluated in different periods, including prechilling, chilling, and chilling maintenance. Analysis show that sufficient cooling can be provided to a RSW tank under most typical engine operation modes, which is significantly influenced by the split ratio and refrigeration capacity ratio. Constraint multi-objective genetic algorithm under engine load of 100% is conducted to determine the maximum potential of the system under the optimum working condition and ensure the smooth operation of the system under all typical engine load. It is estimated that a cooling capacity of 619.9 kW can be offered to the RSW, and the cooling provided to the cold room (502.8 kW) can realize the freezing of 25018 kg fish. After covering the power consumed by compressor and pump, the system still can reach a net power output of 97.32 kW. The thermal efficiency of the engine integrated with the proposed system is improved by 2.89%, and the brake specific fuel consumption is reduced by 5.88%. And the heat rejected by the system can be used to heat water from 25 °C to 45 °C (11.93 kg/s) and 90 °C (2.18 kg/s), respectively. The proposed system shows better overall performance compared to the basic system without ejectors.

Liquid Side Streams from Mussel and Herring Processing as Sources of Potential Income.

The seafood industry generates significant amounts of process waters which can generate value upon recovery of their nutrients. Process waters from the herring marination chain and cooking of mussels were here characterized in terms of crude composition, volatile compounds, and nutritional and potentially toxic elements. Protein and total fatty acid contents of herring refrigerated sea water (RSW) reached 3 and 0.14 g/L, respectively, while herring presalting brine (13%) reached 16.3 g/L protein and 0.77 g/L total fatty acid. Among three herring marination brines vinegar brine (VMB), spice brine (SPB), and salt brine (SMB), SPB reached the highest protein (39 g/L) and fatty acids (3.0 g/L), whereas SMB and VMB at the most had 14 and 21 g protein/L, respectively, and 0.6 and 9.9 g fatty acids/L, respectively. Essential amino acid (EAA) in marination brines accounted for up to 59% of total amino acid (TAA). From mussel processing, cooking juice had more protein (14-23 g/L) than the rest of the process waters, and in all water types, EAA reached up to 42% of TAA. For all process waters, the most abundant nutritional elements were Na, K, P, Ca, and Se. The content of all potentially toxic elements was mostly below LOD, except for As which ranged from 0.07 to 1.07 mg/kg among all tested waters. Our findings shed light on liquid seafood side streams as untapped resources of nutrients which can be valorized into food/feed products.

Using renowned chefs for VeriTaste™ as a sensory method analysis in food products – A comparison of Atlantic salmon stored in refrigerated seawater and on ice

Sensory evaluation is an important quality analysis for examining the characteristics of a food product. This study presents a new sensory analysis method using renowned chefs, branded Veritaste™, to evaluate raw and cooked fillets of Atlantic salmon originating from refrigerated seawater (RSW) versus traditional ice whole fish storage. Quality parameters were also studied, including the fillet index method and cook loss. The raw fillets from the RSW-stored fish had a more distinct salty taste compared to the traditionally stored fish. In addition, the RSW-stored salmon gave a lower cook loss. Otherwise, there were minimal differences in the sensory parameters observed and the fillet index measurements. Both Veritaste™ and the fillet index measurements showed that judges significantly influence the sensory quality parameters. It is concluded that Veritaste™ can serve as supplementary information in addition to the common sensory analyses done today. This method has the potential to be further improved, optimised, and extended to other food products.

Effects of capture-related stress and pre-freezing holding in refrigerated sea water (RSW) on the muscle quality and storage stability of Atlantic mackerel (Scomber scombrus) during subsequent frozen storage

Crowded (stressed) and unstressed Atlantic mackerel with or without pre-freezing holding in refrigerated sea water (RSW) were stored at −19 °C for ∼12 months and analysed for nucleotide degradation (K value), muscle pH, water holding capacity (WHC), fillet firmness, cathepsin B/L like activity, lipid oxidation and fillet colour. The frozen storage showed the largest and most consistent direct effects on the quality metrics leading to increased lipid oxidation, discolouration (yellowing) and reduction on WHC and cathepsin activity. RSW treatment promoted nucleotide degradation and reduced WHC and fillet firmness in interaction with frozen storage and affected fillet colour lightness and saturation. Although showing only marginal main effects, crowding stress modified WHC, cathepsin activity and fillet firmness and colour through significant interactions with the frozen storage and RSW treatment. Further studies with larger sample sizes would be needed to elucidate their complex effects and interactions on the quality and storage stability of mackerel.

Modelling water and salt diffusion of cold-smoked Atlantic salmon initially immersed in refrigerated seawater versus on ice

The effect of dry salting during the cold-smoking process was evaluated on Atlantic salmon initially stored in refrigerated seawater (RSW) or ice. A 2D mathematical model was developed from first principles, simulating the heat and mass transfer process during dry salting at increasing salting duration. This model was validated using experimental values and compared with the empirical model of Zugarramurdi and Lupín. The predicted values were used for water activity prediction and validated. It was found that salting duration influenced drip loss, redness and yellowness, texture, water activity, salt uptake and water loss. Smoked salmon from RSW fish were more reddish with a lower water activity than iced fish after vacuum storage. Drip loss and colour were significantly influenced by the processing step (salting, smoking and storage). Overall, the model presented reasonable predictions for temperature, salt and water content, water activity and was in close agreement with the empirical model.

Risk Assessment of the Use of XyRex® Formulations on Fish Used for Production of Fish Meal to Fish and Animal Feed: Effects on Animal Health, Human Health and the Environment

Risk Assessment of the Use of XyRex® Formulations on Fish Used for Production of Fish Meal to Fish and Animal Feed: Effects on Animal Health, Human Health and the Environment

Skin and vacuum packaging of portioned Atlantic salmon originating from refrigerated seawater or traditional ice storage

The effect of gutted whole fish storage method after slaughter (refrigerated seawater (RSW) −1 °C, ice 0 °C) and common fish packaging methods (vacuum skin, traditional vacuum) in refrigerated storage at 4 °C were investigated. Quality parameters such as pH, drip loss, water holding capacity, colour, texture and microbial growth were analyzed. There was an overall weight gain of 0.9% and salt uptake up to 0.23% for fish stored in RSW for 4 days, followed by ice storage for 3 days. After packaging, pH and hydrogen sulphide producing bacteria in RSW stored fish were lower than iced fish. Drip loss and microbial growth increased through packaged storage, while water holding capacity decreased in all samples. Skin packaged fillets presented a higher drip loss and were lighter, less reddish and less yellowish than traditionally vacuum packaged fillets. Lightness increased, and firmness decreased throughout the experimental period, while redness and yellowness decreased after packaging. Predictive microbiology gave good agreements with the experimental values. It is concluded that storage in RSW extends the lag time of microbial growth and presents good quality traits as those from ice, and the main difference between the packaging methods was drip loss and colour.

Potential for Mesopelagic Fishery Compared to Economy and Fisheries Dynamics in Current Large Scale Danish Pelagic Fishery

Mesopelagic fish species represent a large potentially unexploited resource for the fishing industry and the fish meal, oil, nutraceutical, and pharmaceutical production. However, thorough investigation on ecological sustainability and socio-economic viability are fundamental prerequisites for potential exploitation. The current study explores the economic viability of a potential mesopelagic fishery investigating minimum catch rates, under the assumption of previous assessments of biological sustainability of such exploitation. We analyzed fishery data from the North-East Atlantic fisheries of the Danish large pelagic fleet from 2015 to 2019, by comparing the combined data on fishing dynamics and cost-structures with data from interviews of key pelagic producer organization representatives to develop scenarios of profitability. The results show full year-round fleet occupation with the ongoing fisheries, exposing the need of switching from existing activities, or investing into new vessels for conducting potential mesopelagic fishery. Economic analyses revealed that the minimum revenue to break even (zero profit) by trip varies among métiers between 60,000 and 200,000 euro showing strong positive correlation with vessel sizes. High profitability was discovered for herring, Atlantic mackerel and blue whiting fisheries while low profitability was observed for the Norway pout fishery. Due to the lack of mesopelagic fishery data, different scenarios of profitability were investigated as informed by the pelagic catch sector stakeholder perceptions of prices and costs and compared to current economic dynamics. A high break-even revenue per trip was forecasted given the increased perceived costs for fuel, modifications of gears and on-board processing methods and potential new vessel investments. High profitability may be reached if the catches exceed 220–1,060 tons per trip depending on costs and vessel storage capacity. If the conservation methods are improved from current refrigerated sea water, fishing trips could last longer than 5 days, being the major limiting economic factor for potential mesopelagic fishery. Future investigations on realistic mesopelagic catches, trip durations and spatio-temporal distribution of fisheries in relation to location, resource abundance, fishing rights, storage and conservation methods will be essential to test the robustness of the scenarios proposed in this study, and will in turn benefit of the economic requirements evaluated herein.

A comparative study on quality, shelf life and sensory attributes of Atlantic salmon slaughtered on board slaughter vessels against traditional land-based facilities

The purpose of this study was to investigate the shelf life and quality of Atlantic salmon (Salmo salar) slaughtered onboard vessels and shipped to Denmark in −0.8 °C refrigerated seawater (RSW) as compared to traditional land-based slaughtering facilities having fish on ice. The quality and shelf life were measured on fresh and smoked fillets including blood spot counting, fillet gaping, texture hardness, microbiological counts, Quality Index Method (QIM) and sensory analysis. Blood spot counting and fillet gaping were measured on smoked fillets. Fresh fish slaughtered onboard the vessel had significantly lower fillet gaping scores as compared to those slaughtered at the facility, while no difference was found on smoked fillets. There were no significant differences in blood spots counts nor texture hardness between any of the groups. Salmon slaughtered on the vessel had a significant lower QIM score. The total mesophilic count and H2S producing bacteria for fish slaughtered onboard vessels were significant lower at the end of storage (21d). Sensory analysis after 18 days of storage revealed minimal differences between the groups, whereas fish from the vessel had lower protein precipitation. We conclude that fish slaughtered onboard vessels and transported in superchilled RSW onboard a slaughter vessel presents good quality and improves shelf life over time.

A comparative study of Atlantic salmon chilled in refrigerated seawater versus on ice: from whole fish to cold-smoked fillets

Water and salt uptake, and water holding capacity (WHC) of whole gutted Atlantic salmon superchilled at sub-zero temperatures in refrigerated seawater (RSW) were compared to traditional ice storage. Following the entire value chain, the whole salmon was further processed, and fillets were either chilled on ice or dry salted and cold-smoked. Changes in quality parameters including colour, texture, enzyme activity and microbial counts were also analyzed for 3 weeks. Our results showed that when fish were removed from the RSW tank after 4 days and further chilled for 3 days, an overall weight gain of 0.7%, salt uptake of 0.3% and higher WHC were observed. In contrast, ice-stored fish had a total weight loss of 1% and steady salt uptake of 0.1%. After filleting, raw fillets from whole fish initially immersed in RSW had better gaping occurrence, softer texture, lower cathepsin B + L activity but higher microbiological growth. Otherwise, there were no differences in drip loss nor colour (L*a*b*) on both raw and smoked fillets from RSW and iced fish. Storage duration significantly affected quality parameters including drip loss, colour, texture, enzyme activity and microbial counts in raw fillets and drip loss, WHC, redness and yellowness in smoked fillets.

Effect of chilling technologies on water holding properties and other quality parameters throughout the whole value chain: From whole fish to cold-smoked fillets of Atlantic salmon (Salmo salar)

The effect of different chilling technologies on water holding and quality parameters was investigated on Atlantic salmon throughout the entire value chain. Chilling technologies of whole fish before filleting, included superchilling(S) by refrigerated seawater (RSW) or ice (I), followed by chilling of fillets with liquid nitrogen (SS, IS) or ice (SI, II). Superchilling by shell-freezing with liquid nitrogen (IS and SS) caused increased drip loss throughout storage for both raw and smoked fillets. Whole salmon stored in RSW followed by ice storage (SI) had the least drip loss. Moreover, fish stored in RSW had lower H2S producing bacteria for raw fillets, lower blood spot counts and gaping after smoking. Therefore, this method is likely more feasible than storing whole fish in ice or shell-freezing of fillets. Water content, muscle pH and colour parameters were higher for raw than smoked fillets, while breaking force, firmness and water holding capacity were higher for smoked than raw fillets.

ANALYSIS OF SMALL-SCALE FISH HANDLING DEVELOPMENT IN REMBANG WATERS

Fishing vessels in Rembang Regency, Indonesia, are mostly small-scale ones with a size of less than 10 GT. Small size fishing vessels use ice blocks as a chilling medium during fish handling in the sea. Handling the catch using ice blocks appears to be nonoptimal, so improvement in technology is needed. The aim of the study was to determine alternative fish handling suitable for small-scale fishing management in Rembang Regency. The research employed a descriptive method using the AHP (Analytical Hierarchy Process) analysis related to technological feasibility. The research results of AHP analysis reveal that the weight value of handling fish without using ice is 0.1098, using ice blocks is 0.2711, and using RSW (Refrigerated Sea Water) is 0.6192. Small-scale fish management in Rembang Regency prefers using RSW for handling the catch.

Design and simulations of refrigerated sea water chillers with CO2 ejector pumps for marine applications in hot climates

Various system configurations have been developed to improve the R744 systems under hot ambient conditions. However, stationary land applications are characterised by negligible limits on space for system equipment, unlike the marine industry, i.e. on-board fishing vessels. The baseline CO2 refrigeration system for fishing vessels was developed by a cooperating industrial company, namely the Refrigerated Sea Water Chillers operation on the Norwegian coast, which confirmed the successful application of this approach. In this study, modified layouts are evaluated for operation in warmer climates without the need for an additional compressor unit, thus maintaining the compactness of the unit. Flash gas valve-, parallel compression- and multi-ejector systems were numerically investigated including ejectors section and flooded evaporator. Sea water temperatures as occurring in Mediterranean and East-Asian waters were investigated. Both the optimal high-pressure as well as the pressure level in an intermediate pressure receiver were controlled to achieve low energy consumptions. Finally, an up to 70% performance improvement was obtained in the case of the most advanced installation working in warm East-Asian waters. The obtained results showed that the proper design of the system should ensure no necessity for an additional compressor in warmer climates while still maintaining the designed cooling capacity.

Transient model of an RSW system with CO2 refrigeration – A study of overall performance

Refrigerated seawater (RSW) cooling using CO2 based refrigeration is a relatively new technology that shows promising performance in cold climates. For being a refrigerant CO2 has a low global warming potential (GWP) and is therefore recognized as an environmentally friendly alternative if the unit is competitive on energy efficiency. However, RSW systems with CO2 have a significant reduction in energy efficiency if operated in warm seawater due to its low critical temperature. This study investigates the impact ambient temperature and precooling processes have on performance. The results show that for a fixed process design, lower ambient temperature in the Barents Sea results in an average COP of 5.0 compared with 3.0–3.5 in the Mediterranean Sea, or alternatively, that a ship can operate with RSW tanks that are approximately three times bigger if ambient seawater temperature is 10 °C compared to 20 °C. The study also finds that for a fixed ambient temperature case, the RSW tank can be 3.6–1.8 times larger if one third of the tank volume is precooled.

Quality Determinants of Gillnet-Caught Alaska Salmon

ABSTRACTIn 2010 and 2011, researchers in Bristol Bay, Alaska followed nearly 22,000 tagged sockeye salmon that were caught by 86 selected gillnet boats and delivered unfrozen to tenders anchored out on the fishing grounds. The fish were then chilled in refrigerated seawater (RSW) and transported, usually within 24 h, to a shore-based seafood processing plant, where they were graded using a sensory evaluation method. Handling practices on the fishing boats were documented, along with the distance from the fishing grounds to the processing plant. Fishermen who employed RSW chilling tended to deliver higher quality salmon than fishermen chilling with ice. Fish that were bled at time of harvest and fish that were shaken from the gillnet onto a rubber mat or “salmon slide” were generally of slightly higher quality than fish that were not bled and were dropped onto a hard deck.

Quantification of biomolecules in herring (Clupea harengus) industry processing waters and their recovery using electroflocculation and ultrafiltration

Four types of herring industry processing waters; refrigerated sea water (RSW), storage water (SW), processing water from cutting (PW) and pre-salting brines (SB) were subjected to chemical characterization and biomolecule recovery using electroflocculation (EF) and ultrafiltration (UF). The highest protein and fatty acid content were found in SB's, up to 12.7±0.3 and 2.5±0.1gL−1, respectively. Long chain n-3 polyunsaturated fatty acids represented up to 44.5% of total fatty acids. In all samples, leucine and glutamic acid/glutamine were the dominating amino acids while calcium and magnesium were the dominating trace elements. EF plus UF in series recovered up to 80% proteins and fatty acids from SB's and reduced chemical oxygen demand by 70%. Foaming and emulsifying properties of biomolecules were improved or unaffected by EF/UF treatment. To conclude, large amounts of biomass are currently lost per ton of processed herring, e.g. ∼9.2kg proteins and ∼4.1kg fatty acids; EF/UF represents a promising way of turning such losses to a potential income.

Fillet colour correlates with biochemical status in Australasian snapper (Pagrus auratus) during storage in refrigerated seawater

We demonstrate that two commonly used chilled storage temperatures (4.15 and 0.3°C) differ in their effects on whole rested harvested Australasian snapper (Pagrus auratus) stored in refrigerated seawater (RSW) with respect to white muscle biochemistry and skin and fillet colour. White muscle pH decreased from 7.64 to ca. 6.4 over 48h at both temperatures, but remained significantly (P<0.05) elevated at 4.15°C compared to 0.3°C until 24h post-mortem. This corresponded with significantly elevated potential energy and concentrations of ATP, ADP and glycogen. Depletion of these metabolites occurred by 24h at both temperatures and was mirrored by rises in lactate and inosine monophosphate (IMP). At 24h snapper stored at 4.15°C remained in partial rigor, whereas animals at 0.3°C were in firm rigor. After 72h significantly higher inosine and hypoxanthine concentrations were present in the 4.15°C group, demonstrating temperature related mass action. Tissue biochemistry significantly correlated with changes in fillet colour, particularly redness and yellowness, and we propose that fillet colour can be used as a non-destructive indicator of muscle biochemistry. We link these data with muscle ultrastructure and translucency through histology and with use of a novel laser penetration method.