Reports

Influence of seasonal variation and frozen storage temperature on the lipid stability of Atlantic mackerel (Scomber scombrus)

Published:

01/12/2016

Authors:

Paulina E. Romotowska, Magnea G. Karlsdóttir, María Gudjónsdóttir, Hörður G. Kristinsson, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund (R 040-12)

Influence of seasonal variation and frozen storage temperature on the lipid stability of Atlantic mackerel (Scomber scombrus)

The effect of the storage temperature (-18 ° C vs. 25 ° C) and the fishing season (August vs. September) on the decomposition of fat in Atlantic mackerel caught off the coast of Iceland were examined in this project. Fat stability was assessed by measuring first-stage (PV) and second-degree evolution (TBARS), free fatty acids (FFA) and fatty acid composition. The results show a significant difference in fat degradation with long-term storage, as the degradation was significantly less when stored at -25 ° C compared to -18 ° C. In addition, fish were caught in September with a higher development value compared to fish from August. On the other hand, the most enzymatic fat breakdown was higher in August than in September. The results also indicated that the amount of omega-3 polyunsaturated fatty acids was fairly stable throughout the storage period. In other words, the results showed that the temperature in the cold store had a great effect on fat breakdown, but the stability depended on when the fish was caught.

Lipid deterioration of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters was studied, as affected by different frozen storage temperatures (-18 ° C vs. -25 ° C) and seasonal variation (August vs. September). The lipid stability was investigated by analyzes of hydroperoxide value (PV), thiobarbituric acid reactive substances (TBARS), free fatty acids, as well as changes in fatty acid composition. Results showed significant lipid deterioration with extended storage time, where the lower storage temperature showed significantly more protective effects. Furthermore, a higher lipid oxidation level was recorded for fish caught in September than in August, although lipid hydrolysis occurred to be greater for fish in August than in September. Moreover, results indicated a rather stable level of omega-3 fatty acid during the entire frozen storage period. The analysis indicated that both lipid oxidation and hydrolysis were affected by the frozen storage temperature and the stability differed with regards to season of catch.

Report closed until 01.01.2018

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Reports

Seasonal and geographical variation in chemical composition and lipid stability of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters

Published:

01/12/2015

Authors:

Paulina E. Romotowska, Magnea G. Karlsdóttir, María Guðjónsdóttir, Sigurjón Arason, Hörður G. Kristinsson

Supported by:

AVS Fisheries Research Fund (R 040-12)

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Seasonal and geographical variation in chemical composition and lipid stability of Atlantic mackerel (Scomber scombrus) caught in Icelandic waters

During the time that mackerel is off the coast of Iceland, it is eaten a lot, which causes it to gain weight quickly, with the result that the meat becomes very sensitive to handling. In this study, mackerel caught in the summer seasons of 2012 and 2013 (July, August, September) and from different fishing areas (east, northeast, south and southeast) were examined. In order to assess how well the raw material is suitable for processing high-quality products for human consumption, the mackerel was measured in terms of water and fat content, fatty acid composition, color, coloration and free fatty acids. In general, the mackerel collected in the summer of 2012 was of better quality than mackerel from 2013. The results also indicated a variability between fishing months in terms of fat content and the progress of development. Mackerel caught in the middle of the season had the lowest developmental value, indicating that this mackerel is best suited for processing high-quality products for human consumption.

Atlantic mackerel (Scomber scombrus) appears in Icelandic waters during its heavy feeding period, resulting in variation in mackerel products quality. Fish caught at different season during the summers of 2012 and 2013 (July, August, September) and at different sites of the Icelandic fishing area (East, Northeast, South and Southeast) were analyzed. Measurements of lipid and water content, fatty acid composition, color changes, lipid hydroperoxide (PV), thiobarbituric reactive substances (TBARS) and free fatty acid (FFA) were studied with the aim of investigating whether this raw material was suitable for the production of high quality products for human consumption. In general, samples collected during the summer of 2012 showed a better condition than fish from 2013. The results indicated seasonal variation in lipid content and rancidity development. The lowest rancidity values were observed in the middle of the Icelandic catching season, indicating that this raw material was best suited for production of high quality products. Moreover, geographical variation of the mackerel catches had an impact on the saturation of the fatty acids, and appeared as follows: East> Southeast> Northeast> South.

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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

Production of salted fish in the Nordic countries. Variation in quality and characteristics of the salted products

Published:

01/12/2010

Authors:

Kristín Anna Þórarinsdóttir, Ingebrigt Bjørkevoll, Sigurjón Arason

Supported by:

NORA (Journal No. 510-036)

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Production of salted fish in the Nordic countries. Variation in quality and characteristics of the salted products

The Nordic countries are the largest exporters of salted gadoid products, whereas countries in South ‐ Europe and Latin America are the biggest importers. In Norway, Iceland and Faroe Islands, cod is primarily used for the production. The characteristics of the salted fish, such as commercial quality and weight yield vary between the countries and between producers. These attributes are influenced by differences in catching methods, handling and salting methods. This report summarizes the variation in these procedures, and in addition, the market segmentation of salted products, from the different countries.

The majority of the world's salted fish production takes place within the Nordic countries, but the largest group of consumers is in Southern Europe and South America. Cod is the main raw material, but salted fish is also produced from other related species, such as saithe, ling, haddock and saithe. Properties of salted fish products, such as quality and utilization, vary between countries of production and producers. These variables depend on fishing methods, raw material handling and salting methods. The report is a summary of the variability in these factors between producing countries, as well as an assessment of their share in the salted fish markets.

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