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Reports

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

Author(s):

Hagalín Ásgrímur Guðmundsson, Björn Margeirsson, Sigurjón Arason

Funded by:

AVS research fund (F12 014‐12 and R12 040‐12), “Atvinnusköpun í sjávarbyggðum” research fund.

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

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

Í ágúst 2012 í Tvøroyri í Færeyjum fór fram rannsókn á framleiðslulínu hjá Varðin Pelagic, sem kemur m.a. frá Skaganum hf. á Akranesi. Markmiðið var að bera saman kassaplötufrystiaðferð Skagans við hefðbundna blástursfrystingu með tilliti til orkunotkunar, hitastigs og afurðagæða. Nýtni kassaplötufrysta var metin með tíma‐ og hitamælingum, hermunum á fiskhita gegnum vinnslulínuna og gæðamati á mismunandi stöðum í vinnslunni.

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.

Skýrsla lokuð til 1. apríl 2017

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Reports

Thermal modelling of processing and transport of fresh fish / Hermun kæliferla – LOKASKÝRSLA

Author(s):

Björn Margeirsson, Sigurjón Arason, Kristín Valtýsdóttir

Funded by:

AVS rannsóknasjóður í sjávarútvegi, Tækniþróunarsjóður, Rannsóknasjóður Háskóla Íslands

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Thermal modelling of processing and transport of fresh fish / Hermun kæliferla – LOKASKÝRSLA

Meginmarkmið verkefnisins Hermun kæliferla ‐ varmafræðileg hermun vinnslu‐ og flutningaferla, sem hófst í júní 2008, var að setja fram endurbætur á verklagi og búnaði tengdum flutningi á sjávarafurðum með ferlagreiningu, tilraunum og tölvuvæddum varma‐ og straumfræðilíkönum. Afleiðingar bættrar hitastýringar í vinnslu‐ og flutningaferlum eru aukin gæði, stöðugleiki og öryggi, sem auka um leið verðmæti vörunnar. Samstarfsaðilar í verkefninu voru Matís, Háskóli Íslands, Promens Tempra, Eimskip Ísland, Samherji, Brim (ÚA), Festi, Völusteinn og Eskja. Í þessari skýrslu er helstu niðurstöðum og afurðum verkefnisins lýst. Dæmi um afurðir eru varmaflutningslíkön af ferskfiskafurðum í frauðkassa, sem gera kleift að spá fyrir um fiskhita út frá umhverfishitasögu. Varmaflutningslíkön voru notuð til að endurhanna 3, 5 og 7 kg frauðkassa Promens Tempra með lágmörkun hæsta fiskhita í kössunum undir hitaálagi að markmiði. Tilraunir staðfestu yfirburði nýju kassanna umfram hefðbundnar kassagerðir, bæði m.t.t. hitastýringar og gæða vöru undir hitaálagi. Niðurstöður annarrar tilraunar sýna að geymsluþol ferskra fiskflaka í hornkössum heils bretti í flugflutningskeðju getur verið um 1‐1,5 dögum styttra en flaka í kössum í miðju brettastaflans. Hitadreifing í mismunandi kælikeðjum var kortlögð og sérstök áhersla lögð á forkælingu flaka fyrir pökkun og hitadreifingu í mismunandi tegundum kæligáma með mismunandi hleðslumynstur. 

The main aim of the research project Hermun kæliferla – Thermal modelling 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 modelling. 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 optimise the design of 3, 5 and 7‐kg expanded polystyrene boxes manufactured by Promens Tempra with the aim of minimising 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 prolonged 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 centre 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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Categories
Reports

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

Author(s):

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

Funded by:

AVS Fund of Ministry of Fisheries in Iceland, The Technology Development Fund at the Icelandic Centre 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

Tilgangur tilraunanna var að kanna áhrif mismunandi kælimiðla við forkælingu fyrir pökkun á hitastýringu, gæði og geymsluþol þorskflaka. Eftirfarandi kælimiðlar voru kannaðir og bornir saman við enga sérstaka forkælingu fyrir pökkun:

  1. pækill með lágu saltinnihaldi, 2) krapaís með lágu saltinnihaldi.

Auk þess voru könnuð áhrif þess að nota annars vegar ísmottur og hins vegar þurrís við geymslu flakanna. Fylgst var með breytingum á hitastigi með hitanemum á öllum stigum. Sýni voru gæðametin með skynmati, örveru- og efnamælingum í allt að 13 daga frá vinnslu og pökkun (16 daga frá veiði). Flökin voru geymd við ofurkældar aðstæður (undir 0 °C) mestan hluta geymslutímans. Lægra hitastig krapaíss en pækils leiddi til lægra hitastigs flaka við pökkun auk þess sem hiti vökvapækilsins reyndist hækka hratt þegar hlé var gert á vinnslu. Mismunandi meðhöndlun leiddi til sambærilegs ferskleikatíma samkvæmt skynmati. Hins vegar reyndist notkun vökvapækils við forkælingu fyrir pökkun leiða til 1 – 2 daga skemmra geymsluþols samanborið við enga forkælingu eða forkælingu með krapaís. Rekja má ástæður þessa til þess að pækillinn innihélt töluvert magn örvera, m.a. H2S-myndandi gerla sem eru virkir framleiðendur á trímetýlamíni (TMA). Samanburður á vökvakældu flökunum sýndi að notkun á þurrís lengdi geymsluþol um 1 dag í samanburði við ísmottur. Niðurstöður örveru- og efnamælinga voru í samræmi við þessar niðurstöður.

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 analysed 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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