Reports

Dry-aged fish: First trials to a new product

Published:

17/05/2024

Authors:

Cécile Dargentolle and Dóra Svavarsdóttir

Supported by:

Bára Food Fund - 97473

Contact

Cecile Dargentolle

Project Manager

cecile@matis.is

The purpose of the study was to investigate the possibility of slow-aging "dry-ageing" of different types of fish: lean and fatty. Since the dry-ager was homemade, it was not possible to work with a lower temperature than 4°c. We worked with that temperature and saw how the fish reacted to it. By trying to put both fillets and whole fish in a dry-ager, it was found that it took less time for fillets to reach a similar point of action as whole fish. Shrinkage had to be at least 15% in order to achieve the correct effect: improved texture and taste. These studies also showed that a specially designed and constructed dry-ager would give more accurate answers, as both temperature and humidity can be controlled much better, resulting in a much better final product. pH value, color, water content and shrinkage together with sensory evaluation are promising in the use of slow-aging (dry-ageing) of fish to increase shelf life and more valuable sensory evaluation effects. 
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Those trials were aiming at evaluating the feasibility of dry-aging different types of fish: lean and fatty. As the dry-ager was homemade, the temperature could not be lowered lower than 4°C, allowing the trials to see if the fish would support those temperatures. By trying both fillets and full fish to be dry-aged, the project showed that the time in the dry-age would be shorter for fillet to get to a similar stage than full fish. The weight loss of both should at least be 15% to get a desirable stage: improved texture and taste. Those trials also showed us that commercial dry-ager would present more benefits, as with more stability of both temperature and humidity, the quality of the final product will be better. pH, colour, water content and weight loss as well as sensory showed promising results to use dry-aged fish as a preserving technique to improve both shelf life and sensory characteristics of seafood.  

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Reports

Dry-aged fish: Second trials in a commercial dry-ager

Published:

17/05/2024

Authors:

Cécile Dargentolle and Dóra Svavarsdóttir

Supported by:

Bára Food Fund - 97473

Contact

Cecile Dargentolle

Project Manager

cecile@matis.is

The second part of the research on dry-aging fish focused on increasing the understanding of the parameters that work best (temperature, humidity and time) to achieve the desired characteristics of dry-aged fish. Dry-ageing is a process in which the water content of fish is reduced and the fish deteriorates, until the decomposition of the fish slows down enough to ensure low microbial growth (similar to smoked fish). These studies revealed that it is necessary to work with a lower humidity than 82% and a temperature of 2°c is suitable. The shelf life of fish can be extended by dry-ageing, and a whole fish was kept in the dry-ager for 2 weeks and kept for another 2 weeks without spoiling. Experiments with freezing and storage showed that dry-aged fish is suitable for both. These studies make it possible to make the first statements regarding dry-ageing of fish, as these are the first scientific studies that have been carried out. 
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The second batch of trials from the project dry-aged fish, aimed at understanding which parameters would be best (temperature, humidity, and time) to reach satisfactory dry-aged characteristics to the fish. Dry-ageing is a process where the water content in the fish reduces and the fish loses some weight, to reach a stage where the degradation will be slow enough to ensure low bacterial growth (similar to smoked fish). Those trials showed that humidity should be lower than 82% and that 2°C is working. Shelf life of fish can be extended thanks to dry-aging as whole fish could stay in the dry-ager for at least 2 weeks and then stored for 2 more weeks without having any bad attribute developing. Freezing tests and storage tests allowed to show that dry-aged fish supports both processes. Those trials allowed to set the first statements regarding dry-aging fish, with the first scientific data collected. 

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Reports

Rapid methods for quality evaluation: Evaluation of salted cod following desalting, freezing and storage

Published:

21/03/2024

Authors:

Hildur Inga Sveinsdóttir, María Guðjónsdóttir, Sigurjón Arason, Cecile Dargentolle and Kolbrún Sveinsdóttir

Supported by:

AVS Research Fund and Food Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

This report is closed. 

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Reports

The effect of different desalting methods on the quality of injected brine and pickle salted frozen cod (Gadus morhua)

Published:

21/03/2024

Authors:

Cecile Dargentolle, Hildur Inga Sveinsdóttir, Sigurjón Arason and Kolbrún Sveinsdóttir

Supported by:

AVS Research Fund and Food Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

This report is closed. 

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Reports

Shelf life of differently treated thawed desalted cod loins and tails after storage at -25°C up to 27 months

Published:

21/03/2024

Authors:

Cecile Dargentolle, Hildur Inga Sveinsdóttir, Jónas Baldursson, Sigurjón Arason and Kolbrún Sveinsdóttir

Supported by:

AVS Research Fund and Food Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

This report is closed. 

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Reports

Shelf life of frozen desalted cod (Gadus morhua)

Published:

21/03/2024

Authors:

Cecile Dargentolle, Hildur Inga Sveinsdóttir, Jónas Baldursson, Sigurjón Arason and Kolbrún Sveinsdóttir

Supported by:

AVS Research Fund and Food Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

This report is closed. 

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Reports

Desalting experiments

Published:

21/03/2024

Authors:

Cecile Dargentolle, Hildur Inga Sveinsdóttir, Sigurjón Arason and Kolbrún Sveinsdóttir

Supported by:

AVS Research Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

This report is closed. 

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Peer-reviewed articles

Valorisation of Frozen Cod (Gadus morhua) Heads, Captured by Trawl and Longline by the Oceanic Fleet, by Enzymatic Hydrolysis

Contact

Aðalheiður Ólafsdóttir

Sensory evaluation manager

adalheiduro@matis.is

In the Norwegian oceanic fleet, whitefish onboard processing creates a great amount of rest raw materials. Cod heads are nutritious and a good source for the production of high-quality marine peptides. Frozen cod heads, captured by trawl or longline, were evaluated based on the lightness and redness in the neck cut to compare the quality in heads from the different fishing gears. The heads were subjected to enzymatic hydrolysis. The hydrolysates have been chemically and sensory characterized. There was no significant difference in quality or chemical and sensory characteristics based on type of fishing gear. The resulting hydrolysates were of high quality, although moderately bitter. The study demonstrates that frozen cod heads from the oceanic fleet can be an excellent source of high-quality proteins for human consumption.

Reports

Quality optimization of frozen redfish products

Published:

21/02/2020

Authors:

Ásbjörn Jónsson, Cecile Dargentolle, Huong Thi Thu Dang, Magnea Karlsdóttir, María Guðjónsdóttir, Sigurjón Arason

Supported by:

AVS R&D Fund (R 029-15)

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Maximizing the quality of frozen redfish products / Quality optimization of frozen redfish products

The aim of the study was twofold. Firstly, to explore the influence of time and temperature during frozen storage on lipid deterioration of red fish. That was done by comparing the effect of temperature fluctuation and abuse during frozen storage, as can be expected during transportation, on the physicochemical characteristics and lipid stability of redfish fillets. Secondly, to investigate the effect of 4 days postcatch and 9 days postcatch, and seasonal variation on the quality and storage stability of frozen red fish.

Storage temperature and storage time affected the physical- and chemical properties in redfish, eg free fatty acids, TBARS and TVB-N. Season of capture affected both the nutritional value and stability of golden redfish. The light muscle of fish caught in November was richer in EPA and DHA than in the fish caught in June. The fish caught in November was also more unstable through frozen storage, due to a more unsaturated nature of the fatty acids present, indicating that special care needs to be applied during handling and treatment of golden redfish caught at this time. The light muscle had a higher nutritional value than the dark muscle and is a good nutritional source for human consumption. However, the dark muscle was prone to lipid oxidation which may have a negative influence on the more valuable light muscle. So there seems to be a need to separate them.

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Reports

Holding of Sea Urchins and Scallops in a RAS Transport System

Published:

23/12/2019

Authors:

Guðmundur Stefánsson, Aðalheiður Ólafsdóttir

Supported by:

EIT Food

Contact

Guðmundur Stefánsson

Director of Research Groups

gudmundur.stefansson@matis.is

Holding of Sea Urchins and Scallops in a RAS Transport System

Trials were carried out at Matís on holding live sea urchins and scallops in a RAS system developed by Technion, Israel, which not only recirculates the water, but additionally controls the pH and removes toxic ammonia. The aim of the trials was to test the feasibility of holding sea urchins and scallops alive in the RAS system for 10 days at 4 ° C, with at least 90% survival. The project was funded by EIT food, and the participants were Technion and Matís. 

The survival of sea urchins held in the RAS system at 4 ° C was high during the first five days. Eight days from catch the survival was only 80%, after 12 days about 50% and after 15 days, 10%. Sea urchins, packed in the standard way of transporting live urchins (in polystyrene boxes at 4 ° C) were at similar quality as the RAS stored sea urchins, five days from catch and the roe was still edible at eight days from catch. All the urchins in the polystyrene boxes were dead after 12 days storage and the roe inedible.

Scallops had a high survival when held in the RAS system or about 89% after 24-days at 4 ° C.  

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