Reports

Effect of salt content in slurry ice on quality of fresh and thawed Atlantic mackerel (Scomber scombrus)

Published:

01/12/2015

Authors:

Paulina E. Romotowska, Björn Margeirsson, Gísli Kristjánsson, Sigurjón Arason, Magnea G. Karlsdóttir, Sæmundur Elíasson, Arnljótur B. Bergsson

Supported by:

AVS Fisheries Research Fund (R 12 029-12)

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Effect of salt content in slurry ice on quality of fresh and thawed Atlantic mackerel (Scomber scombrus)

The aim of the experiment was to improve methods of cooling and storage of fresh produce in order to improve the quality of frozen mackerel products. A comparison was made of cooling in conventional ice scrapers and salt-improved ice scrapers. By adding salt to the ice scraper, it was hoped that the temperature of fresh mackerel could be lowered and thus its quality maintained longer. The fresh mackerel was stored for up to seven days after fishing. Another aim of the study was to investigate whether this different cooling of fresh mackerel affects the deterioration of the quality of frozen mackerel products. The results showed that the temperature distribution in the pots was related to salt concentration as lower temperatures were obtained in pots with higher salt content (3.3%). On the other hand, the cold storage had a much greater effect on the quality factors such as the freshness and release of the mackerel products compared to the effect of pre-cooling, as the effect of different salt concentrations in the ice scraper was negligible in terms of these quality factors.

The present experiment is part of the research project - Increased value of mackerel through systematic chilling. The aim of this study was to improve methods of chilling and storing of fresh products in order to obtain better quality of frozen mackerel products. This project was carried out to develop slurry ice mixture with addition of extra salt, with the intention of temperature decrease during chill storage up to seven days after catch. Secondary objective of this research was to investigate if different chilling condition of fresh fish has an effect on the quality assignment of long-term frozen mackerel products. The results showed that temperature distribution in the tubs was correlated to the salt concentration where lower temperature was obtained in the tub with higher salt content (3.3%). Furthermore, freshness, gaping and peritoneum deterioration have been affected by the storage process but not by different salt concentration in slurry ice during chilled storage. Due to high quality variation within the same group of the mackerel is needed to conduct more methods for quality evaluation such as oxidation analysis and sensory analysis.

Report closed until 01.01.2018

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Reports

Increased value of seafood with an emphasis on products for use in fish meal and fish oil production to product development

Published:

01/12/2010

Authors:

Magnús Valgeir Gíslason, Sigurjón Arason, Sindri Sigurðsson

Supported by:

Regional Development Institute, Development Division, Countervailing Grant of the Food Division of the East Iceland Interest Rate Agreement

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Increased value of seafood with an emphasis on products for use in fish meal and fish oil production to product development

In 2008, gold nuggets were first caught in significant quantities, gold nuggets are very sensitive to salt uptake from fishing to processing. To reduce the salt content of the flour, broth from the processing was passed through a membrane filter set up by coarse centrifugation. This equipment was able to reduce the salt content from 11% to 4.5%. Membrane filtration equipment is expensive and has a high maintenance cost to run it in the process. Therefore, it was decided to change the procedure for fishing, storage and landing without changing the production process for flour processing, and this action has resulted in a reduction in the salt content of gold powder flour from 10 - 12 %, which is too high, down to 5 - 6 %.

Silvery lightfish was first caught 2008 near Iceland. Salt diffusion is a problem in silvery lightfish from catch to processing. To lower the salt content in fishmeal the stickwater was put through a membrane filter after coarse centrifuge, with this method the salt content was lowered from 11% down to 4,5%. The membrane filter system is expensive and maintenance cost is relatively high. These are the main reasons for changing procedure while catching, storing and landing without changing the fishmealprocess. This procedure has made salt content in silvery lightfish meal dropp from 10 - 12 % witch was to high down to 5 - 6 %.

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