Categories
Reports

Aukin gæði og stöðugleiki frosinna síldarafurða / Increased quality and stability of frozen herring products

Author(s):

Magnea Karlsdóttir, Huong Thi Thu Dang, María Guðjónsdóttir, Ásbjörn Jónsson, Sigurjón Arason

Funded by:

AVS R&D Fund

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Aukin gæði og stöðugleiki frosinna síldarafurða / Increased quality and stability of frozen herring products

Freezing and frozen storage has proven to be an effective method to preserve and prolong the storage life of seafood products. Production of frozen products provides all year around product availability although the catching is seasonal. There are several factors that can affect the quality and stability of frozen fish products, including the state of the raw material, processing methods and storage conditions.

The aim of the study was to explore how the physicochemical properties of frozen herring fillets are affected regarding the state of the raw material during processing as well as storage conditions. Atlantic herring was processed and frozen pre- and post-rigor and stored at stable (-25 °C) and abused storage conditions. To investigate the storage stability and physical properties of the fillets, thawing drip, cooking yield and colour were evaluated, as well as proximate composition, fatty acid composition, pH and lipid degradation of the light and the dark muscle.

The study demonstrated the importance of stable and controlled temperature during storage and transportation of frozen herring products. Processing and freezing pre-rigor, in combination with stable storage conditions, was shown to be beneficial in terms of preventing lipid oxidation, as well as reducing thawing loss and maintaining the cooking yield of the herring fillets.

See full report
Categories
Reports

Aukin gæði og stöðugleiki frosinna síldarafurða / Increased quality and stability of frozen herring products

Author(s):

Magnea Karlsdóttir, Huong Thi Thu Dang, María Guðjónsdóttir, Sigurjón Arason, Ásbjörn Jónsson

Funded by:

AVS R&D Fund (R 069-14)

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Aukin gæði og stöðugleiki frosinna síldarafurða / Increased quality and stability of frozen herring products

Frysting og frostgeymsla er skilvirk aðferð til að viðhalda gæðum og lengja geymsluþol sjávarafurða. Framleiðsla á frosnum afurðum jafnar framboð afurða þar sem veiðar eru árstíðabundnar. Það eru margir þættir sem geta haft áhrif á gæði og stöðugleika frosinna afurða. Þar má meðal annars nefna ástand hráefnis, vinnsluaðferðir og skilyrði við geymslu og flutning svo fátt eitt sé nefnt. Markmið rannsóknarinnar var að kanna þær breytingar sem eiga sér stað á efna- og eðliseiginleikum frosinna síldarflaka m.t.t. ástands hráefnis við vinnslu og aðstæður í frostgeymslu. Atlantshafssíld var unnin fyrir og eftir dauðastirðnun, og flökin geymd annars vegar við stöðugar geymsluaðstæður (-25 °C) og hins vegar við óstöðugar aðstæður (við -25 °C í 2 mánuði, svo -12 °C í mánuð og svo aftur við -25 °C út geymslutímann). Til að rannsaka stöðugleika og eðliseiginleika afurðanna var m.a. mælt vatnstap (drip), suðunýting og litur, auk þess sem mæld voru bæði í ljósum og dökkum fiskvöðva vatnsheldni, pH, efnasamsetning, fitusýrusamsetning, ensímvirkni og þránun. Rannsóknin sýndi að það er mikilvægt fyrir sjávarútveginn að tryggja samræmda og rétta hitastýringu þegar afurðir eru geymdar í frosti. Vinnsla og frysting fyrir dauðastirðnun, samhliða stöðugum geymsluaðstæðum, hefur jákvæð áhrif á gæði og stöðugleika síldarfalka. Auk þessa, þá staðfesti rannsóknin að fituríki vöðvi síldarinnar, oft nefndur dökki vöðvinn, er mjög viðkvæmur fyrir þránun. Til þess að lengja geymsluþol frosinna síldarflaka er mælt með því að þessi vöðvi sé fjarlægður samhliða roðflettingu (e. deep skinning).

Freezing and frozen storage has proven to be an effective method to preserve and prolong the storage life of seafood products. Production of frozen products provides all year around product availability although the catching is seasonal. There are several factors that can affect the quality and stability of frozen fish products, including the state of the raw material, processing methods and storage conditions. The aim of the study was to explore how physicochemical properties of frozen herring fillets are affected in regard to the state of the raw material during processing as well as storage conditions. Atlantic herring was processed and frozen pre- and post-rigor and stored at stable (-25 °C) and abused storage conditions. To investigate the storage stability and physical properties of the fillets, thawing drip, cooking yield and colour were evaluated, as well as proximate composition, fatty acid composition, pH and lipid degradation of the light and the dark muscle. The study demonstrated the importance of stable and controlled temperature during storage and transportation of frozen herring products. Processing and freezing pre-rigor, in combination with stable storage conditions, was shown to be beneficial in terms of preventing lipid oxidation, as well as reducing thawing loss and maintaining the cooking yield of the herring fillets.

See full report
Categories
Reports

Thermal Performance of Corrugated Plastic Boxes and Expanded Polystyrene Boxes

Author(s):

Björn Margeirsson, Sigurjón Arason, Halldór Pálsson

Funded by:

EU‐project Chill on (project no. FP6‐016333‐2), AVS Research Fund, TÞS Research Fund and University of Iceland Research Fund

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Thermal Performance of Corrugated Plastic Boxes and Expanded Polystyrene Boxes

Tilraunir voru gerðar á einangrunargildi tvenns konar pakkninga fyrir fersk fiskflök: 1) Bylgjuplastkassa (CP) og 2) Frauðplastkassa (EPS). Breytilegu hitastigi umhverfis pakkningarnar var stýrt í tilraunakæliklefum og fylgst með hitaþróun utan og innan pakkninga með hitasíritum. Bæði stakir kassar og heil bretti af kössum voru rannsökuð sem og kæligeta ísmotta, sem stundum eru settar efst í kassa fyrir flutning frá framleiðanda til kaupanda. Kælimotturnar (ísmotturnar) reyndust afar áhrifaríkar til að verja fiskflökin fyrir hitaálagi. Jafnframt sýndu niðurstöður fram á yfirburði varmaeinangrunar frauðplastkassa umfram bylgjuplastkassa óháð notkun kælimotta. Mismunur einangrunargildis er reyndar enn sýnilegri þegar kælimottur eru notaðar.   Tilraunir með fullstaflað bretti af fiskikössum (u.þ.b. 300 kg á bretti) sýndu að meðalhitahækkun flaka getur verið tvöföld fyrir bylgjuplastkassa m.v. frauðplastkassa, að því gefnu að loftið umhverfis sé 10 °C heitt og á töluverðri hreyfingu. Að lokum var sýnt fram á að nokkurra klst. sveiflur í lofthita umhverfis heil fiskibretti geta valdið mjög ójafnri hitadreifingu innan stæðunnar á brettinu.  

Experiments were carried out to compare the thermal performance of two different types of packaging for fresh fish fillets: 1) Corrugated plastic (CP) and 2) Expanded Polystyrene (EPS) boxes. The boxes containing fresh fillets were affected with dynamic thermal loads in air climate chambers. Meanwhile, the fillet temperature was monitored with temperature loggers. Both free standing boxes and whole pallets were affected with dynamic thermal loads in the study and the chilling effect of frozen cooling mats was studied by using them in some of the boxes.    The frozen cooling mats proved very efficient for protecting fresh fish fillets against temperature abuse.  Furthermore, the results show that the insulating performance of EPS is significantly better than of CP, independent of the usage of cooling mats. The difference in insulating performance between the two packaging types is actually exaggerated when cooling mats are used. The experiments with whole pallets revealed that the mean fillet temperature rise for a whole 300 kg fish pallet can be twofold using CP compared to using EPS, given that the movement of surrounding air is considerable and its temperature is 10 °C. Finally, it was shown that in dynamic temperature conditions, the temperature distribution in a whole pallet of fish fillets can be far from homogeneous.

See full report