Tag: Cod

Reports

Seasonal variation of fatty acid composition of cod flesh

Published:

01/03/2012

Authors:

Kristín Anna Þórarinsdóttir, Helga Gunnlaugsdóttir, Jónas R. Viðarsson, Sigurjón Arason

Supported by:

Fisheries Project Fund

Seasonal variation of fatty acid composition of cod flesh

The report summarizes the results of measurements of the chemical content of the liver and cod muscles according to the season and fishing area. The results indicate that seasonal fluctuations in muscle fat content are relatively small. Another issue is the liver, its fat content was found to be lowest in the latter part of winter and in spring. At the same time, the water content was highest. Changes in the chemical composition of the liver were thought to be related to the fluctuations in the behavioral patterns and physical activity of the fish around spawning.

The report summarizes the results from measurements on chemical composition of liver and muscle of cod as affected by fishing grounds and seasonal variation. The results indicate that seasonal fluctuations in fat content of the muscle are relatively low. On the contrary, fat and water content in liver, varied with season. The fat content was lowest late winter and in spring. At the same time, the highest water content in liver was observed. These changes were explained by changes in behavior and physiological functional of the fish in relation to the reproductive cycle.

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Reports

Effect of temperature control on the efficiency of modified atmosphere packaging of cod loins in bulk

Published:

01/06/2011

Authors:

Hélène L. Lauzon, Kolbrún Sveinsdóttir, Magnea G. Karlsdóttir, Eyjólfur Reynisson, Björn Margeirsson, Emilia Martinsdóttir

Supported by:

EU IP Chill ‐ on (contract FP6‐016333‐2)

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Effect of temperature control on the efficiency of modified atmosphere packaging of cod loins in bulk

The aim of the experiment was to compare the freshness, quality and shelf life of sub-chilled (CBC) cod necks in air storage and in aerated packages (MAP) at controlled temperatures to simulate temperature fluctuations during transport and distribution in the European market. Changes in the composition of the gas in the packages were monitored and sensory assessments and microbial and chemical measurements were performed. The fish was caught in bottom trawls in the spring and processed three days after fishing. There was a two-day prolongation during the freshness period and one day for the shelf life of fish in aerated packages (2.7 kg in a tray) compared to air (3.1 kg) in foam plastic, despite a 0.5 ° C difference in the average temperature of the groups and the air group was stored at lower temperatures (‐0.3 ± 0.9 ° C). The greatest temperature fluctuations led to the greatest shortening of the freshness time in air-conditioned packages. Cod saddles stored subcooled at -1.1 ± 0.1 ° C had a shelf life of 13 days. The results of microbial counts and chemical measurements showed the importance of Photobacterium phosphoreum in the formation of TMA in the process of damaging cod necks during both air and air exchange packaging. MAP and subcooling slowed down and changed the damage process. MAP increased drip by 2% in the later stages of storage.

The aim of this study was to compare freshness, quality deterioration and shelf life of CBC (combined blast and contact) ‐treated cod loins packaged in bulk under different atmospheres (air or modified atmosphere, MA) and stored under different temperature profiles to mimic temperature changes during transport and distribution to European markets. Sensory, chemical, microbial and headspace gas composition analyzes were performed regularly. The fish was caught by trawler in the spring and processed 3 days post catch. Following simulation of current sea freight conditions and distribution to European markets, a 2 ‐ day and 1 ‐ day increase in freshness period and shelf life of MA ‐ packaged fish (2.7 kg in trays), respectively, was observed compared to air ‐ stored loins (3.1 kg in EPS boxes). This is despite a mean product temperature difference of 0.5 ° C between the products, being lower (‐0.3 ± 0.9 ° C) for air ‐ stored fish. Abusive conditions had the greatest impact on the reduction of the freshness period for MAP fish. Superchilled storage of MAP loins (‐1.1 ± 0.1 ° C) resulted in a 13 ‐ day shelf life. Evaluation of microbial and chemical indicators emphasized the importance of Photobacterium phosphoreum and TMA formation in the deterioration of cod loins stored in air or MA, while superchilled MAP storage delayed as well as modified the spoilage pattern. MAP increased drip loss by about 2% at late storage.

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Reports

Addition of collagen to heavy salted and lightly salted, chilled and frozen cod fillets

Published:

01/05/2011

Authors:

Kristín Anna Þórarinsdóttir, Hannes Magnússon, Irek Klonowski, Ásbjörn Jónsson, Frank Hansen, Egil Olsen, Sigurjón Arason

Supported by:

NORA

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Addition of collagen to heavy salted and lightly salted, chilled and frozen cod fillets

The effect of added gelatin extracted from fish was investigated on the utilization, chemical composition and quality of chilled, frozen and salted cod fillets. The gelatin was mixed into brine which was then injected into the fillets. Salted fillets were pickled after injection, then salted dry for 3 weeks and finally dehydrated. For comparison, fillets were sprayed only with brine. The main results were that the effect of gelatin on utilization and chemical composition was insignificant. Changes were mainly due to increased salt content. Another issue was the damage processes in chilled products. Microbial growth and degradation formation were higher in the fillets injected with gelatin. However, no visual difference in fillet appearance could be detected by brine composition. 

The effects of added fish gelatin on yield, chemical composition and quality of chilled, frozen and salted cod fillets were evaluated. The gelatin was mixed with salt brine and injected to the fillets. Salted fillets were brined after injection, dry salted for 3 weeks and finally rehydrated. Fillets injected only with salt brine were used as control. Effects of added gelatin on yield and chemical composition were not significant. Alterations were primarily due to the increased salt content by injection. Conversely, the growth of microorganisms and degradation within chilled fillets was accelerated by addition of gelatin. However, no significant differences were observed in visual appearance of the fillets. 

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Reports

Functionality testing of selected Chill ‐ on technologies during a transport ‐ simulation study of palletized cod boxes: qPCR for fish spoilage bacteria, SLP model and QMRA to evaluate pathogen growth in spiked cod

Published:

01/11/2010

Authors:

Hélène L. Lauzon, Björn Margeirsson, Kolbrún Sveinsdóttir, Eyjólfur Reynisson, María Guðjónsdóttir, Emilia Martinsdóttir (Matís); Radovan Gospavic, Nasimul Haque, Viktor Popov (WIT); Guðrún Ólafsdóttir, Tómas Hafliðason, Einir Guðlaugsson, Sigurður Bogason (UoI)

Supported by:

EU IP Chill ‐ on (contract FP6‐016333‐2)

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Functionality testing of selected Chill ‐ on technologies during a transport ‐ simulation study of palletized cod boxes: qPCR for fish spoilage bacteria, SLP model and QMRA to evaluate pathogen growth in spiked cod

In this study, tests were carried out on technical solutions developed in the EU project Chill ‐ on, where a simulation experiment was set up to simulate the actual transport of fish from Iceland to Europe. The temperature fluctuations experienced by the fish were aimed at mimicking transport from Iceland to France by ship. Pallets of cod fillets in foam plastic boxes were transported to the Westman Islands by ship and back to Matís in Reykjavík. Samples from these pallets were then compared with control samples that had been stored in Matís' refrigerated conditions. Cod nuggets were also packed in consumer packs (trays) immediately after processing and then after 6 days and were stored in subcooled or refrigerated conditions. Microbial growth experiments were also performed in which Listeria monocytogenes, Escherichia coli and Salmonella Dublin were added to cod necks stored in foam boxes in conditions similar to the storage and transport processes during export. Temperature measurements, sensory evaluation, microbial and chemical measurements were used to present data to test and verify the QMRA / SLP models and quantification of Pseudomonas bacteria using qPCR technology.

The aim of the cod wet trials and the corresponding shelf life study was to include scenarios to test and demonstrate the functionality of some Chill ‐ on technologies in a simulated cod supply chain. Temperature fluctuations were induced according to the actual scenario in the supply chain of cod from Iceland to France via sea freight. The study included sample groups created at the point of processing after packaging in EPS boxes. The reference group was stored at Matís under superchilled conditions. Simulation trials for downward distribution were performed at Matís upon receipt of the pallets shipped to the Westman Isles from Reykjavik (Iceland ‐ Europe freight simulation) and compared with the reference group. Repackaging of loins in retail trays was performed on days 0 and 6 with storage under superchilled and chilled conditions, respectively. In addition, a pathogen challenge trial was performed by spiking loins (5 kg) with Listeria monocytogenes, Escherichia coli and Salmonella Dublin, followed by storage in EPS boxes under temperature conditions simulating export and distribution. Temperature recordings along with microbial, chemical and sensory analyzes from the groups evaluated provided necessary data to test and validate the QMRA / SLP models and the quantitative molecular (qPCR) method to estimate counts of pseudomonads.

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Reports

Let's look at the yellow from fishing in the stomach - a study of factors that affect the value of cod / Factors influencing the quality and value of the Icelandic cod; a value chain perspective

Published:

01/09/2010

Authors:

Helga Gunnlaugsdóttir, Jónas R. Viðarsson, Ásta M. Ásmundsdóttir, Cecilia Garate, Hrönn Jörundsdóttir, Ingibjörg G. Jónsdóttir, Sigurjón Arason, Vordís Baldursdóttir, Þorsteinn Sigurðsson, Sveinn Margeirsson

Supported by:

Increased value of seafood (AVS), HB ‐ Grandi, Guðmundur Runólfsson hf, Fiskistofa, Hafrannsóknastofnunin, Matís

Let's look at the yellow from fishing in the stomach - a study of factors that affect the value of cod / Factors influencing the quality and value of the Icelandic cod; a value chain perspective

The aim of this project was to gather more detailed information than has previously been done on the chemical composition, processing properties and value of cod in the value chain. The main results of the study are:

• There was not much difference in the carcass of cod by season, but the carcass coefficient was slightly higher in December than around the spawning season (February-May) when it was lowest. No association was found between fish body and liver fat content.

• There was a positive relationship between hepatic index and liver fat content (R2 = 0.55). However, the relationship was not linear, but the fat content increased rapidly at a low liver factor but less as the liver factor increased. Likewise, the fat content of the liver increased with length and age in both hens and females.

Liver fat content, fish weight or body mass index do not provide conclusive evidence of fillet utilization. Likewise, the water content and water resistance of the fillets had little or no effect on production efficiency or emissions.

• The summary result of the assessment of the effect of sex, sexual maturity and age on fillet utilization is that there is a difference in fillet utilization between individual fishing trips, this difference seems to be somewhat dependent on the maturity of the fish and is according to available data lowest at maturity stage 4 (ie fish in spawning or spawning). It should be noted, however, that there is a considerable imbalance in the database regarding the distribution of puberty in individual fishing trips and there are relatively few samples of fish from stages 3 and 4 compared to stages 1 and 2.

A comparison was made of the concentration of PCB7 in cod directly from the sea on the one hand and after processing, ie in frozen fillets, on the other. There was no significant difference in the concentration of PCB7 in whole fish and frozen cod fillets, so fish processing does not seem to affect the concentration of these substances in the fillets.

• There was no statistically significant relationship between iron concentration (Fe), selenium (Se), lead (Pb) or PCB7 and gender, age or puberty. There is a statistically significant relationship between the concentration of mercury in the flesh of cod (ie in fillets) and age, length and sexual maturity. Mercury is known to accumulate in the flesh of fish with age and the results of this study are consistent with and based on these results.

The aim of this project is to collect more detailed data about the factors influencing the quality and value of the Icelandic cod during processing, were the end product is frozen fillet. Data were collected from 2007 to 2008 on fillet yield, water content, water capacity, gaping, parasites as well as the chemical composition (nutrients & undesirable substances). These variables are important for the quality and profitability of the cod industry. Emphasis has been laid on connecting these variables to data about fishing ground, season of fishing, sex, sexual maturity in order to increase our understanding on how it is possible to maximize the value of the catch. In addition, the liver from each individual cod was collected and the fat and water content analyzed. The results from this study show that there is a nonlinear relationship (R2 = 0,55) between the liver condition index and the fat content of the liver.

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Reports

Effect of modified atmosphere packaging (MAP) and superchilling on the shelf life of fresh cod (Gadus morhua) loins of different degrees of freshness at packaging

Published:

01/09/2008

Authors:

María Guðjónsdóttir, Hannes Magnússon, Kolbrún Sveinsdóttir, Björn Margeirsson, Hélène L. Lauzon, Eyjólfur Reynisson, Emilía Martinsdóttir

Supported by:

AVS Research Fund, Rannís Technology Development Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

Effect of modified atmosphere packaging (MAP) and superchilling on the shelf life of fresh cod (Gadus morhua) loins of different degrees of freshness at packaging

The purpose of this experiment was to evaluate the effect of aerated packaging (MAP) and supercooling on the quality changes and shelf life of cod pieces of fresh raw material that was processed and packaged after 2 and 7 days of fishing. The experiment was carried out in collaboration with Samherji, Dalvík and Norðlenska, Akureyri in October and November 2007. The fish was stored whole in ice until packing at -0.2 ± 0.1 ° C (2 days from fishing) and -0.2 ± 0.2 ° C (7 days from fishing). The neck pieces were cut in half and then packed (350-550 g) in an airtight container. The composition of the gas mixture was as follows: 50% CO2, 5% O2 and 45% N2. Packaged cod pieces were stored in cold storage at -0.6 ± 1.4 ° C and samples were taken over a 3-week storage period and evaluated by sensory evaluation, microbial and chemical measurements. The age of the raw material during packaging had a clear effect on the sensory evaluation of the pieces. Packing after 2 days led to a prolongation of the freshness symptoms in front of storage. In addition, signs of damage appeared much later than in bites packed 7 days after fishing. The shelf life of pieces after packing on day 7 can be roughly estimated at 4-8 days, but at least 19 days in pieces packed on day 2. This short shelf life of pieces from day 7 can be explained by the development of microbial flora and the formation of volatile pesticides as well as the temperature profile of whole fish before packaging. The effect of different packing dates had a significant effect on the microflora. Thus, the total number of microorganisms was much smaller in pieces packed after 2 days than on day 7 (log 3.7 vs 5.4 / g). This difference can largely be attributed to the varying number of Photobacterium phosphoreum (Pp) in the flesh immediately after packing, but it was not detected during the previous packing on the 3rd day of the experiment (below log 1.3 / g) and on day 8 the number was only log 2.4 / g. On that day, the number of Pp was 1000x higher in pieces packed on day 7 and they were predominant throughout the storage period in this group. On day 8, the number of other pests (H2S-producing bacteria and pseudomonads) was somewhat higher (Δ log 0.6-0.7 / g) in this group compared to the group packed on day 2. These results confirm that P. phosphoreum is one of the main damaging microorganisms in gas-packed cod pieces but also in chilled, whole cod. The results of TVB-N and TMA measurements were in good agreement with microbial measurements, but especially Pp. Low Field Nuclear Magnetic Resonance (LF-NMR) technology was used to measure relaxation times in samples over the storage period. Significantly higher "relaxation times" were measured in chunks packed after 7 days of fishing than in chunks packed 2 days after fishing. It indicates greater binding of water molecules to the environment in the 7-day bites. This is in line with the generally higher water resistance and water content of those samples over the storage period. Overall, the results show the importance of using the freshest ingredients for MA packaging, thus ensuring higher quality and longer shelf life, which should result in a higher price for the product.

The aim of this study was to evaluate the effect of modified atmosphere packaging (MAP) and superchilling on the shelf life and quality changes of fresh loins prepared from Atlantic cod (Gadus morhua) of different freshness, ie processed 2 or 7 days post catch. The study was performed in cooperation with Samherji (Dalvík, Iceland) and Norðlenska (Akureyri) in October and November 2007. The average fish temperature during storage prior to processing on days 2 and 7 was -0.2 ± 0.1 ° C and -0.2 ± 0.2 ° C, respectively. Cod loins (350-550 g) were packed in trays under modified atmosphere (50% CO2 / 5% O2 / 45% N2), stored at -0.6 ± 1.4 ° C and sampled regularly over a three-week period for sensory, microbiological and chemical analyzes . The results show that the raw material freshness clearly influenced the sensory characteristics of packed loins. Processing 2 days post catch resulted in more prominent freshness sensory characteristics the first days of storage. In addition, sensory indicators of spoilage became evident much later compared to MApacked fillets from raw material processed 5 days later. The expected shelf life of the MA-packed cod loins could be roughly calculated as 4-8 days when processed 7 days post catch, but at least 19 days when the cod was processed 2 days post catch. This reduced shelf life of MAP products processed at a later stage was also explained by the temperature profile of the whole fish prior to processing, microbial development and volatile amine production observed. In fact, the day of packaging had a major effect on the microflora development, with lower total viable counts (TVC) in loins processed earlier in relation to time from catch (log 3.7 vs 5.4 / g). This difference could be linked to large variations in levels of Photobacterium phosphoreum (Pp) in the flesh at processing times, being below detection (log 1.3 / g) 2 days post catch but found to increase to log 2.4 / g in early processed loins 6 days later, in contrast to 1000-fold higher Pp levels in loins processed later. Pp was found to quickly dominate the microflora of loins processed 7 days post catch. Similarly, slightly higher levels (Δ log 0.6- 0.7 / g) of other spoilage bacteria, H2S-producing bacteria and pseudomonads, were found 8 days post catch in loins processed later. These results confirm that P. phosphoreum is one of the main spoilage organisms in cod, unprocessed as MA-processed. TVB-N and TMA production corresponded well to the microbial development, especially counts of P. phosphoreum. Low Field Nuclear Magnetic Resonance (LF-NMR) was used to measure the relaxation times of the samples during storage. The samples packed 7 days after catch showed significantly higher relaxation times than samples packed 2 days after catch. This indicates stronger bindings of the water molecules to their environment in samples packed at a later stage. This is in agreement with the generally higher water holding capacity and water content in the samples during storage. Finally, the results demonstrated that delaying processing of raw material is undesirable if it is intended to be MA-packed and sold as more valuable products.

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Reports

Fat tolerance of cod

Published:

01/07/2008

Authors:

Jón Árnason, Rannveig Björnsdóttir, Helgi Thorarensen, Ingólfur Arnarson

Fat tolerance of cod

The purpose of this study was to investigate the effect of fat content in feed on the growth and cleaning of cod of different sizes. Knowledge of the nutritional needs of fish is a necessary prerequisite for the preparation of feed for them. Two-size cod (120 g and 600 g) were fed (in triplicate) for 12 weeks on feed containing 10.0%, 13.5%, 21.2%, 24.5% and 27.7% fats in dry matter. Different fat content did not affect growth (SGR), body mass index (CF), fillet utilization, liver fat content or fillet fat content. In the smaller fish, the feed index (FCR) decreased with increased fat in the feed. The feed fat did not affect the fat content of offal without liver in the smaller fish (120g) but in 600 g fish the fat in the intestines increased with increased fat content of the feed. The fat content did not affect the proportion of gutted weight of the total weight in the 600 g fish, but in the smaller fish the proportion decreased with increased fat in the feed. Liver ratio (HSI) in 600g fish was not dependent on the fat content of the feed, but there was a positive correlation between feed fat and HSI in the 120 g fish. This means that the fat tolerance of cod in terms of liver ratio depends on the size of the fish.

Detailed knowledge of the nutritional requirements of fish is essential for feed formulation. The aim of this research was to investigate the effects of different lipid content in diets for Atlantic cod of different size. Cod of two size groups (initial weight 120 grams and 600 grams) were fed, in triplicate, for 12 weeks diets containing 10.0%, 13.5%, 21.2%, 24.5% and 27.7% lipid in dry matter. Different lipid content in the diet did not affect growth (SGR), condition factor (CF), fillet yield, lipid content in liver or lipid content in fillet. In the smaller fish, FCR was reduced with increased diet lipid. The lipid content in the diet did not affect the lipid content of intestines in the 120 grams fish but in the 600 grams fish there was a positive correlation between lipid content in diet and intestines. Dietary lipid did not affect gutted weight (calculated as the percentage of round weight) in the 600 grams fish but in the 120 grams fish, the percent gutted weight decreased with lipid content of the diet. The Heposomatic index (HSI) in the 600 gram fish was not affected by the lipid content of the diet but dietary lipid content significantly affected the HSI in the smaller fish. This indicates that the lipid tolerance of Atlantic cod, with respect to the effect on HSI, is size dependent.

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Reports

Oxidation in fish muscle - The role of phospholipids, proteins, antioxidants and the effect of boiling on oxidation in fish muscle

Published:

01/04/2008

Authors:

Rósa Jónsdóttir, Margrét Bragadóttir, Guðrún Ólafsdóttir

Supported by:

RANNÍS Research Fund

Contact

Rósa Jónsdóttir

Research Group Leader

rosa.jonsdottir@matis.is

Oxidation in fish muscle - The role of phospholipids, proteins, antioxidants and the effect of boiling on oxidation in fish muscle

The aim of the project was to increase the understanding of the effects of oxidation in fish muscles, which reduces the taste and nutritional value of fish. The effects of added natural antioxidants or antioxidants were assessed to improve the stability of fish products and thus increase the possibility of using fish in prepared dishes. A phospholipid model from cod was used to examine the effects of stimulants (hemoglobin from cod and char) and inhibitors in the liquid phase from capelin and Icelandic algae. The effect of boiling and added anti-corrosion substances on the taste properties and the formation of a so-called heating taste in boiled fish mince was also examined. The effect of oxidation on membrane phospholipids and proteins in the fish muscle model and in the fish mince during heating and storage was measured by sensory evaluation, color measurements, conventional evolution measurements (TBA), gas spectrometry measurements to identify volatile odorants and electrophoresis capillary capillary peptile and amino acids that affect taste and bioactivity. The relationship between these factors was examined to explain and better understand the oxidation process in fish muscles and the factors that limit the shelf life of prepared fish products. The main negative effects of oxidation on fish quality were the formation of odorants, mainly aldehydes, which are fatty acid degradants. Membrane fat in lean fish can therefore have a significant effect on the taste quality of prepared foods, despite being in small quantities. Oxidative stimuli such as blood in the flesh and boiling led to faster oxidation, which shows that with proper bleeding and mild heat treatment, oxidation could be limited and the taste quality of fish could be better maintained. In addition, oxidation can be reduced through the use of antioxidants. Measurements of the antioxidant activity of capelin broth in a fish muscle model showed that variable external factors such as seasonal fluctuations and the treatment of capelin raw material can affect the antioxidant activity. A novelty in this project is a basic study of the effects of capillaries and algae, as well as changes in the decomposition products during welding, which have a direct effect on the taste quality of the product. Research in this area is being continued in new projects that focus on better looking at natural antioxidants from capelin and algae, as well as their health-promoting effects.

The aim of the project was to study the effect of heating on oxidation of phospholipids, and the role of antioxidants in fish muscle to influence sensory quality and nutritional value. A phospholipid model from cod was used to study the effect of pro-oxidants (hemoglobin from cod and trout) and antioxidants in aqueous fraction of capelin and in seaweed extracts. The effect of heating and the addition of antioxidants on the sensory quality and the development of warmed-over-flavor (WOF) in fish mince were also studied. The development of degradation compounds in washed cod model system during storage and heating was studied by sensory analysis, color measurements, traditional lipid oxidation analysis (TBA) and gas chromatography analysis to identify volatile compounds. Capillary electrophoresis (CE) was applied for the analysis of peptides and amino acids that influence the sensory quality and bioactivity. The correlation between these analyzes was studied to better understand the oxidation processes in fish muscle and to explain factors reducing the shelf life of ready-to-eat fish products. Quality defects related to oxidation of polyunsaturated fatty acids and formation of volatile compounds like aldehydes contributing to rancidity and color changes were enhanced by pro-oxidative effects of blood and cooking. Membrane bound phospholipids are therefore of concern as precursors for off flavor and quality defects in lean fish despite of low fat content. Capelin broth appeared to have antioxidant effects in fish model system whereas press juice from whole capelin exhibited pro-oxidant effects. The outcome of this project is increased knowledge on oxidation in fish muscle to underpin the development of healthy and tasteful fish products of high sensory quality and nutritional values fulfilling the needs of consumers. Continued studies have been established in new projects to further characterize the antioxidant properties and possible health effects of capelin and seaweed extracts.

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Reports

Gender analysis of fish

Published:

01/11/2007

Authors:

Dr. Sigurlaug Skírnisdóttir, Msc. Eiríkur Briem, Msc. Hlynur Sigurgíslason, Dr. Guðmundur Ó. Hreggviðsson, Dr. Sigríður Valgeirsdóttir, Dr. Jónas Jónasson, Dr. Sigríður Hjörleifsdóttir

Supported by:

Technology Development Fund (Icelandic Research Centers)

Contact

Sigurlaug Skírnisdóttir

Project Manager

sigurlaug.skirnisdottir@matis.is

Gender analysis of fish

The aim of the project was to find a gender-related difference between the genetic material of pike and females in salmon, halibut and cod. This information was then to be used to develop a gender analysis test for these fish species. Gene and female repositories for the three species were prepared by subtraction pairing. The sequences obtained in the gene pool were sequenced, palpated, and then plated. The flakes were then paired with genetic material on the hens and females and the binding was assessed for the sexes. The project involved a great deal of technical and market innovation, combining high-tech methods from molecular genetics and information technology to solve the existing market problem in gender analysis in aquaculture. The risk in the project was whether there was a sufficient gender difference in the genome of these fish to detect it by flake analysis. This project was a great challenge and although the final goal was not achieved, it worked out in terms of methodology and great results were obtained. The project was therefore important for development and method development within the companies Stofnfisk, Matís-Prokaria and Nimblegen Systems in Iceland.

The goal of the project was to develop a sex determination method for the three fish species, cod, salmon and halibut. Gene libraries for female and male fishes were produced for the three fish species by using the subtraction hybridization method from whole genomic DNA. Probes were designed for all the sequences obtained and the probes were put on microarrays. The microarrays were hybridized with DNA from both male and female fishes and the difference scored. The risk of the project was to determine if there is enough gene difference between the sexes of these three fish species to be analyzed by using microarrays. The project did not reveal sex determination genes, but this assignment was a big challenge for the three companies Stofnfiskur, Matís-Prokaria and Nimblegen Systems. Many new methods and technical solutions were solved during the project and a large set of results were built up. The project was an important part of the fast growing and development of the companies.

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Reports

Process control for fishing, processing and processing of salted fish. Effect of cooling after fishing on the muscular structure of cod

Published:

01/08/2007

Authors:

Valur N. Gunnlaugsson, Jónína Ragnarsdóttir, Þóra Valsdóttir, Kristín Anna Þórarinsdóttir

Supported by:

AVS, Rannís Technology Development Fund

Contact

Valur Norðri Gunnlaugsson

Research Group Leader

valur.n.gunnlaugsson@matis.is

Process control for fishing, processing and processing of salted fish. Effect of cooling after fishing on the muscular structure of cod

This report describes the results of a cod image analysis. The effect of cooling methods after fishing on the muscular cod stock was assessed. It was not possible to detect differences in fillets depending on whether the fish had been stored in liquid ice or flake ice in a train or had been cooled separately on deck. Muscle changes during salt fish processing were monitored and the effect of injection was assessed. During salting, cells contracted and the extracellular space increased. There was a clear difference in the fillets depending on whether they were injected or not. During dehydration, the difference due to injection decreased again.

Results from image analyzes on cod are discussed in this report. The effects of chilling methods after catch on microstructure of cod fillets were also evaluated. No significant effects were observed, neither when extra chilling was added on deck nor with regard to different ice types (liquid ice / flake) used for storage of the fish. Changes in the fish muscle during heavy salting were examined and the effects of injection as the initial step in the process studied. During salting muscle cells shrank and the ratio of extracellular fluid increased. Significant effects of injection were observed after salting but during rehydration the difference decreased again.

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