Reports

The effect of mortality on fish quality ll

Published:

15/08/2019

Authors:

Gunnar Þórðarson, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund (R 17 019-17)

contact

Gunnar Þórðarson

Regional Manager

gunnar.thordarson@matis.is

The effect of mortality on fish quality ll

The purpose of the study was, on the one hand, to investigate the effect of supercooling on the death-hardening process of cod and salmon fillets and to compare with conventional cooling; and, on the other hand, to examine whether filleting at different times in the death solidification process (before mortality, in mortality and after the process ends) had a product quality. For salmon, a preliminary experiment was performed on which the main experiment was based, while in cod an experiment was performed on wild cod and farmed fish.

Supercooling of cod is based on cooling down to -0.8 ° C and salmon at -1.2 ° C, while conventional cooling is based on 0 ° C for both species. Differences between groups were examined and also differences within groups were compared. Small differences within groups indicate a more accurate and credible conclusion.

The results of a survey carried out by a sensory evaluation team show that the effect of supercooling is considerable as there is less contraction in the death solidification process, and the effect on quality is therefore smaller. There is a difference between wild cod and farmed cod, as it is known that the water content between cells is less in farmed development than wild. It might be interesting to look at the difference between farmed salmon and wild salmon, but that was outside the scope of this study.

It can be concluded that with supercooling it would be possible to process salmon for freezing to death without degrading quality, which could be important in the marketing of fresh products in the future, as the salmon could be processed immediately at slaughter and thus increase shelf life in foreign markets.

One of the aims of the project was to prepare promotional material on the death solidification process and its impact on the quality of products for salmon and cod producers in Iceland, which could benefit them in the future in tackling new challenges in the production of high-quality products.

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Reports

The effect of rigor mortis on fillet quality

Published:

01/10/2016

Authors:

Gunnar Þórðarson, Albert Högnason, Anton Helgi Guðjónsson

Supported by:

AVS Fisheries Research Fund (R 16 014-16)

contact

Gunnar Þórðarson

Regional Manager

gunnar.thordarson@matis.is

The effect of rigor mortis on fillet quality

The purpose of the study was, on the one hand, to investigate the effects of supercooling on freezing and comparing it to conventional refrigeration, and on the other hand to prepare promotional material that could be used to introduce stakeholders in the fisheries sector to the importance of controlling the freezing process. A study was carried out on cod and salmon and it was carried out at two different seasons for cod, but there can be great differences in the condition of the raw material depending on when and where the fish is caught. The study was twofold in that, on the one hand, data were obtained on the effect of cooling on the death solidification process, where the groups were compared; supercooled and traditional, and on the other hand to interpret the results for promotional material. Supercooling in cod is based on cooling down to -0.8 ° C and salmon at -1.5 ° C, while conventional cooling is based on 0 ° C for both species. Differences between groups were examined as well as comparing differences within groups. Small differences within groups indicate a more accurate and credible conclusion. The results show that there is a large difference in the contraction of the fish muscle when it goes through the freezing process, depending on whether it is supercooled or conventional cooling is used. It can be concluded that there is a great quality benefit in the use of supercooling for death stiffness, which reduces contraction and consequently reduces tension between muscles and spine. With too fast and too much contraction of the death stiffness, the muscle can easily be damaged, such as loosening, the stiffness of the fillets decreases, etc.

The purpose of this project was to study the effect of superchilling on rigor mortis process and compare it to traditional chilling with ice. Also to prepare promotional material to enlighten the fishery industry on the importance of managing the process of rigor mortis for product quality. A study was conducted on cod and salmon, including seasonality effect on rigor mortis for cod. The definition on sub chilling in this study is; for cod it is based on cooling to -0.7 ° C and for salmon down to -1.5 ° C and for traditional chilling by ice is targeted at 0 ° C for both species. The rigor process was studied between groups, sub-chilled and traditional, and within groups to investigate standard deviation between samples to sample credibility of outcome. The results indicate a large difference in the contraction process on whether the fish is super chilled or traditional cooling used. The conclusion of the study indicates that sub chilling, which reduces the contraction and consequently the tension between muscle and backbone in the process, can have a large effect on fillet quality, less gaping and a firmer product.

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