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Guidelines for precooling of fresh fish during processing and choice of packaging with respect to temperature control in cold chains

Author(s):

Kristín Líf Valtýsdóttir, Björn Margeirsson, Sigurjón Arason, Hélène L. Lauzon, Emilía Martinsdóttir

Funded by:

AVS Fund of Ministry of Fisheries in Iceland (R-037 08), Technology Development Fund at the Icelandic Centre for Research (081304508), University of Iceland Research Fund and EU (contract FP6-016333-2)

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Guidelines for precooling of fresh fish during processing and choice of packaging with respect to temperature control in cold chains

Tilgangur leiðbeininganna er að aðstoða við val á milli mismunandi aðferða við forkælingu ferskra fiskafurða ásamt því að aðstoða við val á pakkningum með tilliti til hitaálags sem varan verður fyrir á leið sinni frá framleiðanda til kaupanda. Fjallað er um eftirfarandi forkælingaraðferðir: vökvakælingu, krapaískælingu og roðkælingu (CBC, snerti- og blásturskælingu). Einnig er fjallað um meðferð afurða á meðan vinnslu stendur og áhrif mismunandi kælimiðla á hitastýringu, gæði og geymsluþol flaka áður en vörunni er pakkað. Leiðbeiningarnar taka mið af vinnslu á mögrum hvítfiski, s.s. þorski og ýsu. Niðurstöður rannsókna sýna að vel útfærð forkæling fyrir pökkun getur skilað 3 – 5 dögum lengra geymsluþoli m.v. enga forkælingu fyrir pökkun. Ófullnægjandi vökvaskipti við vökvakælingu með tilheyrandi krossmengun geta þó gert jákvæð áhrif forkælingarinnar að engu. Íslenskir ferskfiskframleiðendur notast einkum við frauðplastkassa (EPS, expanded polystyrene) og bylgjuplastkassa (CP, corrugated plastic) til útflutnings á ferskum flökum og flakabitum. Hér er því eingöngu fjallað um fyrrgreindar pakkningagerðir. Niðurstaðan er sú að ef hitastýring er ófullnægjandi og hitasveiflur miklar er æskilegt að nota frauðplastkassa sem veita betri varmaeinangrun en bylgjuplastkassar.

The aim of the guidelines is to provide and assist with choice of different precooling techniques for fresh fish fillets as well as assist with choice of packaging with respect to thermal abuse, which the product experiences during transport and storage from processor to customer. The following precooling techniques are discussed; liquid cooling (LC), slurry ice cooling (SIC) and combined blast and contact cooling (CBCC). In addition, the following is discussed; handling during processing and the effect of applying different cooling media before packaging on temperature control, quality and shelf life of fresh fillets. The guidelines are designed with lean white fish muscle in mind, such as cod and haddock. The results reveal that efficient precooling before packaging can prolong shelf life up to 3 to 5 days compared to no precooling before packaging. If the liquid exchange in the liquid cooler’s circulation system is insufficient, cross-contamination can diminish the positive effects of precooling. Icelandic fresh fish processors mainly use expanded polystyrene (EPS) and corrugated plastic (CP) boxes for export of fresh fish fillets. The guidelines are therefore only focused on the above-mentioned packaging types. The conclusion is that if temperature control is unsatisfactory and temperature fluctuations are great, then expanded polystyrene boxes are the preferred alternative because they provide better insulation.

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