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Quality optimization of frozen redfish products

Author(s):

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

Funded by:

AVS R&D Fund (R 029-15)

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Hámörkun gæða frosinna karfaafurða / Quality optimization of frozen redfish products

The aim of the study was twofold. Firstly, to explore the influence of time and temperature during frozen storage on lipid deterioration of red fish. That was done by comparing the effect of temperature fluctuation and abuse during frozen storage, as can be expected during transportation, on the physicochemical characteristics and lipid stability of redfish fillets. Secondly, to investigate the effect of 4 days postcatch and 9 days postcatch, and seasonal variation on the quality and storage stability of frozen red fish.

Storage temperature and storage time affected the physical- and chemical properties in redfish, e.g free fatty acids, TBARS and TVB-N. Season of capture affected both the nutritional value and stability of golden redfish. The light muscle of fish caught in November was richer in EPA and DHA than in the fish caught in June. The fish caught in November was also more unstable through frozen storage, due to a more unsaturated nature of the fatty acids present, indicating that special care needs to be applied during handling and treatment of golden redfish caught at this time. The light muscle had a higher nutritional value than the dark muscle and is a good nutritional source for human consumption. However, the dark muscle was prone to lipid oxidation which may have a negative influence on the more valuable light muscle. So there seems to be need to separate them.

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Styrene migration from expanded polystyrene boxes into fresh cod and redfish at chilled and superchilled temperatures

Author(s):

Erwan Queguiner, Björn Margeirsson, Sigurjón Arason

Funded by:

RPC Tempra

Contact

Sigurjón Arason

Head Engineer

sigurjon.arason@matis.is

Styrene migration from expanded polystyrene boxes into fresh cod and redfish at chilled and superchilled temperatures

Markmið tilraunarinnar var að rannsaka mögulegt flæði stýrens úr frauðplastkössum í fersk þorsk- og karfaflök, sem geymd eru við dæmigert hitastig í sjóflutningi á ferskum flökum frá Íslandi til Evrópu eða Ameríku. Amerískir kaupendur óska eftir því að fiskflökum sé pakkað í plastpoka fyrir pökkun í frauðplastkassa vegna mögulegrar stýrenmengunar úr frauði í fisk. Því var í þessu verkefni mælt stýren í fiski, sem geymdur hafði verið án plastpoka í frauðkössum, og magn stýrens borið saman við viðmið bandaríska matvæla- og lyfjaeftirlitsins (FDA). Í heildina voru 12 frauðkassar, sem innihéldu þorsk- eða karfaflök, geymdir í 4, 7 eða 13 daga við annaðhvort -1 °C eða 2 °C, sem samsvarar annars vegar ákjósanlegasta og hins vegar hæsta líklega hitastigi í sjóflutningi með fersk flök. Eitt 10-50 g sýni var tekið úr neðsta hluta neðsta fiskflaks í hverjum kassa og hafði þar með verið í beinni snertingu við frauðplast og því komið fyrir í glerflösku. Því næst voru sýnin 12 send til greiningar hjá Eurofins, alþjóðlegri rannsóknastofu í Þýskalandi. Niðurstöðurnar sýna að magn stýrens, sem og annarra óæskilegra efna líkt og bensens og tólúens, var undir 0,01 mg/kg fisks í öllum tólf fisksýnunum. Viðmið (hámark) FDA er 90 mg af stýreni í hverju kg af fiski á einstakling á dag, sem jafngildir skv. niðurstöðum þessarar tilraunar er að neytandi þarf að neyta daglega 9000 kg af fiski til að nálgast viðmið FDA sem er mjög óraunhæft magn. Meginniðurstaða þessarar tilraunar er því að ekki er nauðsynlegt að pakka ferskum fiskflökum í plastpoka fyrir pökkun í frauðplastkassa, sem geyma og flytja á við kældar og ofurkældar aðstæður.

The aim of the study was to investigate possible styrene migration from expanded polystyrene into fresh cod and redfish, two important export fish species in Iceland, while stored under conditions mimicking transport by ship from Iceland to America and Europe. American buyers wish to have a plastic bag between EPS boxes and fish during transport as a safety measure due to possible styrene migration. Thus, this project was conducted to investigate if adding a plastic bag is necessary with regards to safety limits for styrene migration from packaging to food set by the FDA (US Food and Drug Administration). A total of twelve samples of cod and redfish were stored in EPS boxes manufactured by Tempra ltd. for 4, 7 and 13 days at two temperatures (-1 °C, 2 °C) which represent optimal and expected maximum storage temperatures during sea transport of fresh fish. A sample of 10-50 grams of fish, which had been in direct contact with the packaging, was taken from the bottom of each box, as it is considered the most hazardous place regarding styrene migration, and put in a glass bottle before analysis. Finally, the twelve samples of fish were sent to Eurofins, an international laboratory in Germany, for analysis. The results show that styrene content, and other solvent residues like benzene or toluene, were below 0.01 mg/kg in all twelve samples of fish. The FDA’s daily intake limit of styrene is 90 mg/kg per person per day, which means that in this study an unrealistic intake of at least 9000 kg of fish would be necessary to exceed this FDA´s limit. The main conclusion from this study is therefore that a plastic bag is not needed to safely pack cod and redfish fillets into EPS boxes to be stored under chilled and superchilled temperatures.

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Changes in visual and textural quality in the redfish species (Sebastes marinus) during different storage regimes / Tilraunir gegn blettamyndun í ferskum karfaflökum

Author(s):

Heather Philp, Ragnheiður Sveinþórsdóttir, Anna Hjaltadóttir

Funded by:

AVS (V 11 019-11)

Changes in visual and textural quality in the redfish species (Sebastes marinus) during different storage regimes / Tilraunir gegn blettamyndun í ferskum karfaflökum

Fisktegundin Sebastes marinus eða karfi eins og hún er kölluð í daglegu tali var viðfangsefni þessa verkefnis þar sem markmiðið var að finna orsök og leysa það vandamál sem blettamyndun er á ferskum karfaflökum. Þessir blettir sem myndast á ferskum karfaflökum eru gulleytir og myndast innan fimm daga frá vinnslu flakanna, það skapar vandamál vegna flutningstíma þeirra og skerðir gæði þeirra vegna sjónrænna áhrifa. Rannsóknirnar sem voru framkvæmdar í verkefninu ná yfir þessa fimm daga sem tekur blettina að myndast. Í tilraunum þar sem reynt var að koma í veg fyrir blettamyndunina var ferskum karfaflökum pakkað annars vegar í frauðplastkassa þar sem motta á botninum leysti út koltvíoxíð á meðan hinn hermdi flutningur átti sér stað og hins vegar var flökunum pakkað einu og einu í lofttæmdar umbúðir þar sem var einnig motta undir þeim sem hleypti út koltvíoxíði. Niðurstöðurnar voru þær að með þessum umbúnaði flakanna var komið í veg fyrir oxun lípíða í holdinu en bæði sjónræn áhrif og áferð flakanna versnuðu. Önnur tilraun var þá gerð þar sem karfi var blóðgaður um leið og hann var tekinn um borð í veiðiskipið og hann borinn saman við karfa sem kom óblóðgaður að landi (eins og venjan er) yfir fimm daga tímabil. Niðurstöðurnar urðu þær að blettirnir voru minna áberandi í fiskinum sem hafði verið blóðgaður um borð í veiðiskipinu. Lokaniðurstöður urðu þær að líklegur orsakavaldur þessara gulleytu bletta sem myndast á ferskum karfaflökum sé tengd niðurbroti á litarefnum sem innihalda járn s.s. blóðrauða og mýóglóbini.

The species Sebastes marinus, commonly known as redfish, is the subject of a series of experiments aimed at determining the cause and mitigation of the appearance of yellowish stains on the surface of processed fillets. These detract from the visual quality and occur within five days of processing, thus precluding their transport to customer by sea and reducing their potential value. An investigation of progression described the appearance of the staining over a five day period. An attempt to prevent the staining was carried out by packing the fillets in two forms of modified atmosphere, one where the fillets were maintained in standard boxes with the addition of carbon dioxide releasing pads, and one where the fillets were individually sealed in vacuum bags with carbon dioxide releasing pads. It was found that the packaging prevented oxidation of lipids in the muscle but the visual and textural quality was greatly reduced. A further investigation monitored the appearance of stains in fish that had previously been bled at sea. It was found that the yellowish stains were less apparent in the bled fish compared to those that had not been bled. In addition, the textural quality was again reduced suggesting this may be a most suitable method for improving the quality such that the fresh fillets may be transported by sea. It is proposed that the likely cause is related to the breakdown of ironcontaining pigments such as haemoglobin and myoglobin.

Skýrsla lokuð til 01.12.2016

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