Reports

Modeling of Temperature Changes, Energy Usage and Quality Changes During Automatic Box Freezing of Mackerel

Published:

01/04/2013

Authors:

Hagalín Ásgrímur Guðmundsson, Björn Margeirsson, Sigurjón Arason

Supported by:

AVS research meeting (F12 014‐12 and R12 040‐12), “Job creation in coastal areas” research meeting.

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Modeling of Temperature Changes, Energy Usage and Quality Changes During Automatic Box Freezing of Mackerel

In August 2012 in Tvøroyri in the Faroe Islands, a study was carried out on the production line at Varðin Pelagic, which comes from Skagan hf. in Akranes. The aim was to compare Skagan's box plate freezing method with conventional blow freezing in terms of energy consumption, temperature and product quality. The efficiency of box plate freezers was assessed by time and temperature measurements, simulations of fish temperature through the processing line and quality assessment at different points in the processing.

In August 2012 a trip was made to Tvøroyri, Faraoe Islands to measure and analyze Vardin Pelagic's new production line by Skaginn among others. The goal was to compare the automatic box freezing method to the commonly used blast freezing method in terms of energy usage, temperature and product quality. The efficiency of the automatic box freezer was evaluated by mapping the processing time and ambient temperature effects, simulating the product temperature in the production line and performing quality assessment throughout the production line.

Report closed until April 1, 2017

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Reports

Thermal modeling of processing and transport of fresh fish / Hermun kæliferla - LOKASKÝRSLA

Published:

01/09/2011

Authors:

Björn Margeirsson, Sigurjón Arason, Kristín Valtýsdóttir

Supported by:

AVS Fisheries Research Fund, Technology Development Fund, University of Iceland Research Fund

Contact

Sigurjón Arason

Chief Engineer

sigurjon.arason@matis.is

Thermal modeling of processing and transport of fresh fish / Hermun kæliferla - LOKASKÝRSLA

The main objective of the project Simulation of cooling processes - thermodynamic simulation of production and transport processes, which began in June 2008, was to present improvements in procedures and equipment related to the transport of marine products through process analysis, experiments and computerized thermal and hydrological models. The consequences of improved temperature control in production and transport processes are increased quality, stability and safety, which at the same time increase the value of the product. Partners in the project were Matís, the University of Iceland, Promens Tempra, Eimskip Ísland, Samherji, Brim (ÚA), Festi, Völusteinn and Eskja. This report describes the main results and products of the project. Examples of products are heat transfer models of fresh fish products in a foam box, which make it possible to predict fish temperatures based on environmental temperature history. Heat transfer models were used to redesign the Promens Tempra 3, 5 and 7 kg foam boxes with the minimum target fish temperature minimization under the target heat load. Experiments confirmed the superiority of the new boxes over traditional box types, both in terms of temperature control and product quality under heat load. The results of another experiment show that the shelf life of fresh fish fillets in corner boxes of whole pallets in the air transport chain can be about 1-1.5 days shorter than fillets in boxes in the middle of the pallet stack. Heat distribution in different cooling chains was mapped and special emphasis was placed on pre-cooling fillets for packing and heat distribution in different types of cooling containers with different loading patterns. 

The main aim of the research project Hermun kæliferla - Thermal modeling of processing and transport of fresh fish, which was launched in June 2008, was to improve technology and practices used for fish processing and transport by means of analysis of chill chains, experiments and computational modeling. Improved temperature control in fish chill chains leads to increased product quality, stability and safety and thereby increased product value. This report describes the main results and products of the project. Examples include heat transfer models of fresh fish fillets packaged in boxes, which can be used to predict product temperature evolution as a function of variable ambient temperature. Numerical heat transfer models were used to optimize the design of 3, 5 and 7 ‐ kg expanded polystyrene boxes manufactured by Promens Tempra with the aim of minimizing the maximum fish temperature in boxes under thermal load. Improved thermal protection of the new box design was confirmed in different experiments, both with regard to lesser product temperature variations and extended freshness period and storage life of products. The results from another storage study suggest that the storage life of fresh fish products in a corner box can be more than 1‐1.5 days shorter than in the center boxes of a full size pallet stack in a real air transport chain, depending on the level of ambient thermal load. Environmental and product temperatures were mapped in different chill chains with special emphasis laid on precooling during processing and temperature distribution in reefer containers of different types and loading patterns. 

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Reports

The effect of different precooling media during processing and cooling techniques during packaging of cod (Gadus morhua) fillets

Published:

01/04/2010

Authors:

Björn Margeirsson, Hannes Magnússon, Kolbrún Sveinsdóttir, Kristín Líf Valtýsdóttir, Eyjólfur Reynisson, Sigurjón Arason

Supported by:

AVS Fund of Ministry of Fisheries in Iceland, The Technology Development Fund at the Icelandic Center for Research, University of Iceland Research Fund

Contact

Kolbrún Sveinsdóttir

Project Manager

kolbrun.sveinsdottir@matis.is

The effect of different precooling media during processing and cooling techniques during packaging of cod (Gadus morhua) fillets

The purpose of the experiments was to investigate the effect of different refrigerants in pre-cooling before packaging on temperature control, quality and shelf life of cod fillets. The following refrigerants were examined and compared with no special pre-packing pre-packing:

  1. brine with a low salt content, 2) ice cream with a low salt content.

In addition, the effects of using ice mats and dry ice on the storage of the wrecks were investigated. Temperature changes were monitored by temperature sensors at all levels. Samples were quality assessed by sensory evaluation, microbial and chemical measurements for up to 13 days from processing and packaging (16 days from fishing). The fillets were stored in supercooled conditions (below 0 ° C) for most of the storage time. Lower temperatures of slurry ice than brine led to lower fillet temperatures during packing, and the temperature of the liquid brine was found to rise rapidly during processing. Different treatment resulted in a comparable freshness period according to sensory evaluation. However, the use of a liquid brine during pre-packaging pre-packing proved to lead to a shorter shelf life of 1-2 days compared to no pre-cooling or pre-cooling with slush ice. The reasons for this can be traced to the fact that the brine contained a considerable amount of microorganisms, including H2S-producing bacteria which are active producers of trimethylamine (TMA). Comparison of liquid-cooled fillets showed that the use of dry ice prolonged shelf life by 1 day compared to ice mats. The results of microbial and chemical measurements were consistent with these results.

The aim of the experiment was to investigate effects of two cooling media during precooling at processing on temperature control, quality and storage life of cod fillets. The two cooling media compared to no special precooling during processing (NC) were: 1) liquid brine (LC) and 2) slurry ice (SIC). In addition, the influence of using either dry ice or ice packs during storage was studied. The samples were kept at superchilled conditions during most of the trial. The environmental and product temperature history of each group was studied using temperature monitors. The samples were analyzed with sensory evaluation, microbial and chemical methods for up to sixteen days from catch (thirteen days from processing). Lower temperature of the slurry ice than the liquid brine resulted in lower fillet temperature at packaging and the liquid brine temperature increased rapidly during a processing break, which seems to be a weakness of the liquid brine tank. Results from sensory, microbial and chemical analysis all showed that immersing the skinless cod fillets in liquid cooling brine prior to packaging resulted in one to two days reduction of shelf life in comparison with fillets that were not immersed in liquid brine (no cooling) or in slurry ice. This could be attributed to the fact that the cooling brine carried considerable amounts of microbes including H2Sproducing bacteria which are active producers of trimethylamine (TMA). Comparison of the groups receiving liquid cooling showed that dry ice appeared to extend the shelf life of one day as compared to ice packs. The length of the freshness period was, however, similar in all experimental groups according to sensory evaluation. These results were confirmed by total volatile bases (TVB-N) and TMA analysis and microbial counts.

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