Reports

Overview of available methods for thawing seafood / Solutions available for thawing seafood

Published:

01/06/2017

Authors:

Sigurður Örn Ragnarsson, Jónas R. Viðarsson

Supported by:

The Norwegian Research Council (Project number 233709 / E50)

Overview of available methods for thawing seafood / Solutions available for thawing seafood

There is a constant demand for quality raw materials that can be used for producing seafood products for high paying markets in Europe and elsewhere in the world. Suppliers of demersal fish species in the North Atlantic are now meeting this demand by freezing the mainstay of their catches, in order to be able to have available supplies all year around. This is partly done because of seasonal fluctuations in catches, which are harmful from a marking point of view. The fact that all these raw materials are now frozen demands that methods used for freezing and thawing can guarantee that quality of the raw material is maintained. There are a number of methods available to thaw fish. The most common ones involve delivering heat to the product through the surface, as with conduction or convection. These methods include water and air-based systems. More novel methods are constantly on the rise, all with the aim of making the process of thawing quicker and capable of delivering better products to the consumer. These procedures are however, often costly and involve specialized workforce to control the process. All in all, it depends greatly on what kind of conditions a company is operating under regarding which thawing methods should be chosen. This report identifies the most common methods available and provides information on their main pros and cons.

There is a constant demand from fish processing plants around the world for good raw materials from the North Atlantic for the production of products for demanding markets. To meet this demand and in view of the large seasonal fluctuations in catches of certain fish species, companies have decided to freeze the raw material for later use. This requires good methods for freezing the raw material, but it is no less important that the thawing of the raw material is good. There are many methods for thawing fish and other seafood. It has been most common to use heat transfer through surfaces with heat transfer or thermal conductivity. These methods are mostly based on the use of water or air as a medium for thawing. Newer methods exist that try to make the process faster and thus deliver a better product to consumers. However, these methods are often costly and involve a great deal of staff specialization. After all, it matters what kind of business it is and how the companies' situation is at any given time when thawing methods and technical solutions are chosen. This report identifies all the major thawing methods and the technical solutions available on the market today, as well as outlining their main advantages and disadvantages.

View report

Reports

Thawing of frozen cod fillets

Published:

31/10/2016

Authors:

Ásbjörn Jónsson, Magnea Karlsdóttir, Einar Sigurðsson, Sigurjón Arason

Supported by:

AVS Fisheries Research Fund

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Thawing of frozen cod fillets

The aim of the project was to study methods for thawing cod fillets in blocks and to find the best and possible method for thawing for markets abroad. The result of the project is to lead to an increase in the quality of products made from frozen raw materials and streamlining of processing which leads to lower production costs. It was also found that the method of tempering (semi-thawing) was realistic, provided that the temperature and time of thawing were adjusted.

The object of the project was to explore methods for thawing of seafrozen codfillets and find the potential methods for thawing. The culmination of the project is to lead to increased quality of products derived from frozen fillets and rationalization of processing, resulting in lower production costs. The main results showed that the best method, of the methods tested, was thawing in water with air circulation. It was also revealed that tempering was realistic, provided to adjust the temperature and time of thawing.

View report

Reports

Sókn á ný mið / Thawing processes

Published:

01/12/2010

Authors:

Róbert Hafsteinsson, Albert Högnason, Sigurjón Arason

Supported by:

Technology Development Fund

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Sókn á ný mið / Thawing processes

This project is a joint project of Brims hf, Matís ohf and 3X Technology ehf and aims to develop new equipment and processes for thawing gutted catfish for processing. The project was for two years and was funded by the Technology Development Fund. The project contains several experimental reports that were made by the participants of the project and were carried out in Brims' premises in Akureyri. The experiments were largely based on examining the heat distribution of cod at different thawing temperatures on the lake. Thermal inserts were placed in the core and redness of the cod to monitor the temperature in the fillet. The aim was to try to find out the best thawing method in terms of the quality of the raw material after thawing and storage in the refrigerator overnight. The main variables in these experiments were time and temperature. The thawing was tested in a so-called auger made by 3X Technology in Ísafjörður. By using snails in thawing, it will be very easy to control the thawing time and also ensure that the raw material that enters first comes out first. The main results of the project were that the best result from the thawing in terms of color and loss of the fillet in the processing was to thaw the cod in the shortest possible time and have the temperature of the water (thawing temperature) even throughout the thawing process. Then after storage in the refrigerator overnight, the temperature of the fish is about zero to -1 ° C. This will give the best result in terms of the quality of the raw material.

This project is a collaboration work between Brim hf, Matis ohf and 3X Technology ehf. The project objectives is to develop a new equipment and processing for thawing fish. This project is for two years and is supported by Icelandic Center for Research (Rannis). This project contains several experiment reports and their payoff which was executed by the members of this project. All these experiments were done within Brims accommodation. Their main object was to investigate the temperature gradient of codfish with various thawing temperature. Thawing experiments were executed in so called screw tank, manufactured by the company 3X Technology. By using these tanks you will ensure that the fish whos goes first in the tank will go first out when thawing is over. And thereby all control of time and temperature will be much easier. The primary conclusion from this project is that the best outcome from the thawing experiment, when taking into account the color and looseness of the fish fillet, is to have the thawing time as short as possible and the temperature of the water as even as possible throughout the thawing process.

View report

Reports

Freezing and thawing of Greenland halibut - experiments and CFD simulation

Published:

01/10/2009

Authors:

Björn Margeirsson, Lárus Þorvaldsson, Sigurjón Arason

Supported by:

AVS, TÞS, UI Research Fund

contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Freezing and thawing of Greenland halibut - experiments and CFD simulation

Freezing and thawing of halibut were studied experimentally and computerized thermodynamics (CFD) models. Whole pallets of semi-frozen halibut were placed in a cold store and the air temperature and halibut temperature in different places on the pallet were measured by thermometers. The time taken for the halibut to freeze from -10 to -5 ° C below -15 ° C ranged from one to four days depending on the location of the pallets. In thawing experiments, both individual bags and twenty bags, stacked on pallets, were examined in the temperature-controlled cold rooms of Matís and UI. The heating of a frozen product was mapped under conditions that may occur during unloading from freezer trawlers or 10 - 20 ° C air temperature. The results of the experiments were compared with the results of three-dimensional heat transfer models, and there was generally good agreement between them. At 10 p.m. storage at 12.6 ° C air temperature raised the temperature in individual bags from about -26 ° C to approx. ‐5 ° C. At such a long temperature load, the temperature in pallet bags rose from -22.5 ° C to from -17 to -3 ° C, which shows how homogeneous the heat distribution can be with prolonged heat load. The results of the CFD model showed that 10 m / s wind during loading significantly accelerates the thawing of frozen fish on pallets.   

Freezing and thawing of Greenland halibut was investigated with experiments and computational fluid dynamics (CFD) models. A whole pallet of half ‐ frozen halibut was put in a frozen storage and ambient temperature and fish temperature at different locations in the stack monitored. The required freezing time from ‐10 - ‐5 ° C down to ‐15 ° C was one to four days depending on the location within the stack. In the thawing experiments, both single, free standing halibut bags and twenty halibut bags stacked on a pallet, were investigated in an air climate chamber. The warm up of full ‐ frozen product was mapped under typical temperature conditions during unloading of products from freezer trawlers, ie at 10 - 20 ° C ambient temperature. A good comparison between the CFD simulation and experimental results was obtained. Fish temperature increased from ‐26 ° C to - 5 ° C inside single bags when thermally loaded for 10 hours at 12.6 ° C ambient temperature. Equally long temperature abuse for the whole pallet, initially at ‐22.5 ° C, resulted in a very inhomogeneous temperature distribution from ‐17 to ‐3 ° C. The results from the CFD modeling showed that 10 m / s wind during unloading seriously accelerates thawing of frozen fish.

View report
en_GBEnglish