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Superchilled Round Fish – Final Report / Ofurkældur heill fiskur – Lokaskýrsla

Author(s):

Björn Margeirsson, Valur Oddgeir Bjarnason, Sigurjón Arason

Funded by:

AVS rannsóknasjóður í sjávarútvegi (R 11 062‐11)

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Superchilled Round Fish – Final Report / Ofurkældur heill fiskur – Lokaskýrsla

Meginmarkmið verkefnisins „Ofurkældur heill fiskur – fyrir dauðastirðnun“, sem hófst í júlí 2011, var að kanna hvort ofurkæling heils fisks um borð í veiðiskipi gæti lengt geymsluþol og aukið gæði afurðanna. Hæfilegra hita‐ og tímastillinga á roð‐ og snertikæli var leitað með fjórum kælitilraunum og bestu stillingarnar notaðar til ofurkælingar heilla fiska í geymsluþolstilraun. Niðurstöður geymsluþolstilraunar benda til þess að ofurkæld vinnsla á heilum þorski geti lengt geymsluþol hans um tvo daga. Samkvæmt skynmati var þó lítinn mun að finna á geymsluþoli mismunandi flakahópa. Geymsluþol var metið 16–18 dagar, sem er nokkuð langur tími fyrir þorskflök. Ferskleikatímabil tilraunahóps með ofurkældum flökum úr ofurkældum heilum fiski virtist þó vera heldur lengra en hinna hópanna. Líkt og fyrir heila þorskinn reyndist lítill munur milli flakahópanna m.t.t. örveruvaxtar, efna‐  og eðliseiginleika. Takmarkaðan mun milli tilraunahópa má mögulega skýra með stöðugum og ofurkældum geymsluaðstæðum. Með hliðsjón af því er ráðlagt að framkvæma aðra sambærilega tilraun þar sem hermt yrði eftir dæmigerðari umhverfishitaferlum í flutningi ferskfiskafurða (0–4 °C) en í þessari tilraun (–1.4 til –1.2 °C). Niðurstöður tölvuvæddrar varma‐  og straumfræði‐líkanagerðar gefa til kynna að þess lags líkön gætu nýst til áframhaldandi hönnunar á roð‐ og snertikæli fyrir heilan fisk.

The main aim of the R&D project „Superchilled round fish – pre‐rigor“, which was initiated in July 2011, was to investigate if superchilled processing of whole fish on‐board fishing ships could increase the product quality and prolong storage life. The appropriate temperature‐  and time‐settings for the superchilling equipment was studied in four cooling trials and the best settings applied when preparing samples for a storage life study. The results from the storage life study indicate that superchilled processing of whole cod can extend storage life by two days. However, differences in sensory scores between the fillet groups were small. Storage life was estimated between 16 and 18 days which is quite long storage life for cod fillets. However, the group with superchilled fillets from superchilled whole fish seemed to retain freshness a little longer than other groups. As in case of the whole cod, the differences in bacterial count, chemical and physical properties between the fillet groups were small. Very similar fish temperatures between both the whole fish and the fillet groups resulting from the superchilled storage conditions applied may be the main reason for the small differences obtained. Thus, another study with more common temperature conditions during transport and storage of fresh fish (chilled but not superchilled) should be performed. The results obtained in this study show that CFD modelling of fluid flow and heat transfer is a realistic and functional tool to simulate superchilling of whole fish in a CBC‐cooler. In future work CFD‐modelling can be used to determine optimal values for parameters such as holding time, chilling temperature and air velocity. 

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