Fish protein solutions were extracted from cod (Gadusmorhua) trim using the pH-shift process. Fresh and frozen stability of cod protein solutions (CPS) [at 3% protein, pH 7.9, and different levels of salt, with/without cryoprotectants (sucrose, sorbitol and polyphosphate)] stored for different times and temperatures were studied. The results indicated that the fresh CPS was spoiled microbiologically after 3 days of storage at +2°C. Viscosity (Brabander Unit) decreased in samples containing 3% and 5% salt and increased in samples containing 10 and 15% salt after 2 days of storage at +2°C. Viscosity of fresh samples containing 10% and 15% salt decreased with storage time. The expressible moisture and whiteness of fresh samples were not influenced by the storage time. Adding cryoprotectants to CPS containing 1.2, 3, 5 and 15% salt increased the water holding capacity (WHC) and decreased the expressible moisture. It also increased viscosity (BU) in samples containing 3 and 5% salt significantly after 14 weeks of storage at -24°C. The cryoprotectants had no significant effect on improving the whiteness of the samples. The storage time also increased the expressible moistureand decreased WHC in frozen samples. The most stable frozen samples were those with 5% salt and cryoprotectants followed by the samples with 3% salt and cryoprotectants.
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Phosphate blend can be used in salted cod processing to improve yields, water holding capacity and appearance of the final product. However, added phosphates are gradually degraded during processing and storage, leading to changes in functional properties of phosphates. The objective of the study was to monitor the quantitative and qualitative changes in added phosphates in cod during salting, storage and rehydration using ion chromatography (IC) and spectrophotometric analysis. The phosphates diffused into the fish muscle during brining but the phosphate content (mg P2O5/g sample) decreased again as liquid drained away from the muscle in the following dry salting step. Changes during six months storage of the dry salted products were minor. Further losses were observed during rehydration where the phosphates were washed out to levels lower than in the raw material.
The advantage of the IC method was the ability to separate and determine different soluble phosphate species in the fish muscle. The IC results showed that pyrophosphate (P2O7) and triphosphate (P3O10) were partly degraded into orthophosphate (PO4) during the storage period. Lower values were obtained for the total phosphate content by IC than with the spectrophotometric method, which explained by difference is sample preparation.
A dietary study was undertaken to test the effect of different protein and lipid levels in feed for turbot, Scophthalmus maximus (Rafinesque, 1810) in the grow-out phase (initial size 580 g). The experimental diets were formulated to contain 35 (LP), 42.5 (MP) and 50 (HP) % crude protein (CP), protein with a subsequent level of 15 (LL) and 25 (HL) % crude lipid (CL) for each protein level. Final weights and specific growth rates were significantly affected by the dietary treatments. Fish fed the low protein low lipid (LP/LL) diet displayed lower final mean weight compared to fish fed the high protein (HP/LL and HP/HL) diets. The overall SGR was higher in the HP/LL group compared to both low protein groups and the MP/LL group. The calculated feed conversion efficiency (FCE) demonstrated that turbot are able utilize high lipid feed efficiently and that lipids are essential when fish are fed diets with reduced amounts of protein. No clear relationship was found between CP content in feed and CP in fillet. CL in fillet were, however, affected by dietary CL, where fish fed the LP/HL and MP/HL diets had elevated levels of CL in fillet. The diets did not affect the texture properties of the fillet, whereas some differences were found regarding water holding capacity (WHC) and muscle pH in fillet. The present findings suggest that CP can be reduced by approximately 10% compared to current level in commercial feed without negative effects on growth. This will make production of a more cost efficient and less expensive feed for large turbot (> 500 g) possible.
A study was carried out to evaluate temperature variation and quality deterioration of packaged cod fillets as influenced by the box type used and their position on pallets under dynamic temperature storage. Storage life of thermally abused fillets was compared to that of fillets stored at steady temperature. Thermal performance of fish boxes, made of corrugated plastic on one hand and expanded polystyrene on the other hand, was also compared. Fillet temperature at multiple positions on the pallets along with environmental temperature and humidity were monitored during storage. Differences in product temperature of up to 10.5 °C were recorded on the thermally abused pallets stored for 6.4 h at mean ambient temperature of 18.5 °C. A reduction in storage life of 1.5–3 days was observed depending on the box position on the abused pallets compared to steady temperature storage.
A mathematical model for heat transfer from surrounding environment to a single food package is developed. A simplified analytical solution for three-dimensional (3D) unsteady temperature distribution in the food package with rectangular geometry taking into account the ambient temperature is obtained. The model is developed to be used as an efficient tool for estimating the effects of temperature abuse on the food product inside a single packaging unit. The food product is considered to be a homogenous solid body. The packaging material and air inside the package are modeled using an effective heat transfer coefficient. The developed model is validated by a comparison with experimental results obtained for fresh haddock fillets in expanded polystyrene (EPS) boxes exposed to temperature abuse and by comparison with numerical results obtained by the commercial software FLUENT. A satisfactory agreement was obtained between the experimental and numerical results.
Temperature variations in cod fillets packaged in four levels of EPS boxes stored on pallets under thermal load were studied numerically and experimentally. In the experiment the fillet temperature along with environmental temperature were monitored at 39 positions on the pallets during 9-h dynamic temperature storage between 7 and 23 °C. A three-dimensional time-dependent heat transfer model was developed using the ANSYS FLUENT Computational Fluid Dynamics (CFD) software. The overall mean absolute error of the model was 0.3 °C and the maximum error obtained at a single position over the whole period was 2.4 °C. The model was further developed in order to simulate temperature evolution inside a fully loaded, 12-level pallet under the same dynamic temperature conditions as a four-level pallet studied before. The mean temperature after 9-h thermal load was 1.0 °C lower in the 12-level pallet but the maximum temperature evolution was similar in both pallets. Finally, the model was used to investigate the temperature-maintaining effect of superchilling fish before the thermal load.
Fourteen new microsatellite loci were developed and tested on Atlantic herring Clupea harengus with 39 individuals from Iceland and 49 individuals from Norway. The microsatellites, which contain di, tri and tetranucleotide repeats, are polymorphic (7–30 alleles), with observed heterozygosity ranging between 0·69 and 1·00 and expected heterozygosity between 0·55 and 0·97.
Background/objectives: Significant changes have been reported in dietary habits and food availability in Iceland that would be expected to compromise selenium intake and status, especially among young people. These include substantial decreases in the consumption of fish and milk, as well as the selenium content of imported wheat. The aim of this study was to assess selenium in the diet and whole blood of adolescent girls, as well as define the most important foods contributing to intake and blood concentrations of selenium.
Design: The subjects were 96 randomly selected girls, aged 16-20, who answered a validated food frequency questionnaire (FFQ) for dietary assessment. Selenium intake from each food group was calculated in mg/day. Blood samples were collected for measurement of whole blood selenium.
Results: Mean dietary selenium was 51 ± 25 mg/day. Milk/dairy products, including cheese, contributed 36 ± 14% of total dietary selenium; fish 18 ± 12%; and bread/cereal products 13 ± 6%. Mean whole blood selenium was 117 ± 12 µg/l (range 90-208); nearly 90% of subjects were above the optimal level of 100 µg/l. Fish and bread/cereal products were the only foods significantly correlated with selenium in blood (r = 0.32; P =0.002 and r = 0.22; P = 0.04, respectively) while no correlation was found with milk and dairy products in spite of their greater contribution to total selenium intake.
Conclusion: In this population of Icelandic adolescent girls, selenium intake and status seem acceptable. Judging from associations between intake and blood levels, fish and cereals may be the most important contributors to blood selenium.
The North Atlantic fin whale (Balaenoptera physalus) undertakes long-distance annual migration between high-latitude summer feeding locations and low-latitude winter mating locations, like most of the baleen whales. By statistically comparing genotype profiles of mother-foetus pairs (n = 23) to that of the potential alleged father (n = 139) captured at the same feeding location in Iceland, we found a matching pairing of a mother-foetus captured in 2009 and a father captured in 2010. To our knowledge, the present study is the first one to detect a mother-foetus pair matching with an alleged father, caught at exactly the same feeding area one year later.
Temperature history from three air and three sea freights of fresh cod loins and haddock fillets in expanded polystyrene boxes from Iceland to the U.K. and France were analyzed to find out the effect of different factors on the temperature profile and predicted remaining shelf life (RSL) of the product. It was also aimed to pinpoint hazardous steps in the supply chains. Significant difference (P < 0.001) was found in: the temperature at different locations inside a certain box; mean product temperature between boxes of a certain shipment; and the boxes’ surface temperature at different positions on a pallet for the whole logistics period. The predicted RSL depends on the time and temperature history of the product, shortest for sea transportation and longest for an air shipment with precooled product. Several critical steps were found in air freighting: the flight itself, loading/unloading operations and holding storage at unchilled conditions.