Flokkur: Greinar
The impacts of climate change on marine ecosystems can be seen in the changing distribution, migration, and abundance of species in the oceans. For some species this changing environment may be beneficial and can support population expansions. In the northeast Atlantic (NEA), the Atlantic mackerel (Scomber scombrus) is undergoing an increase in stock size accompanied by changing summer migration patterns, which have resulted in an expansion further north and north west than previously recorded. This study uses microsatellite loci to confirm the differentiation among NEA and northwest Atlantic (NWA) mackerel spawning populations and to assess the level of structuring within these populations. In addition, to enable population-specific exploitation rates to be factored into fisheries management, we identified the origin of individuals composing the expanding feeding aggregations in the central north Atlantic (Greenland, Iceland, Faroes), with all aggregations tested originating from spawning populations in the NEA. This study showed that microsatellite loci were useful to assess the contribution of NEA and NWA populations to mixed feeding aggregations across the north Atlantic for large pelagic fish stocks but were not powerful enough to evaluate the specific contribution of known stocks within NEA and NWA.
To study the effects of dairy production system on milk macromineral and trace element concentrations, milk samples were collected monthly in 2019 from 43 conventional and 27 organic farms. Organic milk contained more Ca (1049.5 vs. 995.8 mg/kg), K (1383.6 vs. 1362.4 mg/kg), P (806.5 vs. 792.5 mg/kg) and Mo (73.3 vs. 60.6 μg/kg) but less Cu (52.4 vs. 60.6 μg/kg), Fe (0.66 vs 2.03 mg/kg), Mn (28.8 vs. 45.0 μg/kg), Zn (4.51 vs. 5.00 mg/kg) and Al (0.32 vs. 1.14 μg/kg) than conventional milk. Significant seasonal variation was observed in all determined minerals’ concentrations. Milk I concentration was not consistently affected by production system, whereas organic milk contained less I in June and July than conventional milk. Dietary factors contributing to different milk mineral concentrations between production systems included intakes of maize silage, dry-straights and oils (higher in conventional diets), and pasture, clover and wholecrop (higher in organic diets).
The potential of seaweeds as food is gaining increasing interest among Western consumers. This trend is supported by the nutritional benefits of several species such as Palmaria palmata. Product flavor is a major factor governing consumer acceptance. Developing more attractive flavors in edible seaweeds is a key to sustain the current health food movement based on this resource in Europe. Semi-dry (SD) storage of P. palmata was investigated as a mean to increase its sensory quality. SD-samples containing 20% moisture and dried (D) samples (6% moisture) stored up to 126 days were studied. SD-samples stored for a long period (61 and 126 days) developed a distinct sweet, rich, complex flavor and odor as well as a softer texture compared to SD-samples stored for a shorter period (12 days) and D-samples stored for 126 days. Variations in nutritional compounds and physico-chemical properties among samples along with increasing levels and diversity of volatile compounds in SD-samples during storage compared to D-126 suggest that a variety of flavor compounds arise from biochemical reactions involving lipids, proteins and carbohydrates. These reactions are either endogenous or the result of the activity of microorganisms naturally present in the seaweed. They are promoted by a higher moisture content than in dried material (20% vs 6%) and long storage times. These results provide a basis which can be applied to control the storage conditions of seaweeds to produce flavor-rich ingredients attractive to Western consumers.
The data article refers to the paper “Semi-dry storage as a maturation process for improving the sensory characteristics of the edible red seaweed dulse (Palmaria palmata)”. The data refers to the analysis of samples of the edible seaweed species Palmaria palmata during storage in a dry (D, containing ca. 6 % moisture) and semi-dry state (SD, containing ca. 20 % moisture). The article includes data from the analysis of samples taken at 0, 12, 61 and 126 days of storage to evaluate the effect of moisture content and storage time on the sensory characteristics of the product. The variations in flavor, odor and texture between samples were measured by sensory evaluation. Data from the analysis of flavor-active compounds (free amino acids and volatile compounds), macronutrient content (soluble proteins and carbohydrates, lipid and mineral fractions), physico-chemical properties (water activity, water and oil-binding capacities, swelling capacity), color and microbial load are also reported. The information provided in this article can be used by industrial stakeholders (seaweed producers, food industry) to optimize processing and storage conditions of edible seaweeds and by scientists to build upon further knowledge to improve the quality of seaweeds in food applications.
In the Norwegian oceanic fleet, whitefish onboard processing creates a great amount of rest raw materials. Cod heads are nutritious and a good source for production of high-quality marine peptides. Frozen cod heads, captured by trawl or longline, were evaluated based on the lightness and redness in the neck cut to compare the quality in heads from the different fishing gears. The heads were subjected to enzymatic hydrolysis. The hydrolysates have been chemically and sensory characterized. There was no significant difference in quality or chemical and sensory characteristics based on type of fishing gear. The resulting hydrolysates were of high quality, although moderately bitter. The study demonstrates that frozen cod heads from the oceanic fleet can be an excellent source of high-quality proteins for human consumption.
A method for the determination of inorganic arsenic (iAs) without chromatography using hydride generation — inductively coupled plasma mass spectrometry (HG-ICPMS) is applied to 40 brown macroalgae samples (Fucus vesiculosus, Ascophyllum nodosum, Saccharina latissima). Determining iAs in seaweed matrices is a challenge and, in this study, using 2% HNO3 and 3% H2O2 extraction media the HG-ICPMS outperformed the most commonly used method of HPLC-ICPMS for the determination of iAs in the seaweed samples. There was a good comparison between the simple and fast HG-ICPMS and the more accurate but time-consuming HPLC-HG-ICPMS. Linear regression showed reasonable linearity (R2 of 0.82), with a slope slightly higher than 1 (1.15 ± 0.09) and intercept 0.03 ± 0.01 when comparing the concentrations of iAs determined with the two methods. Hence there is a minor overestimation of iAs with HG compared to the HPLC-HG, however, the method is well suited as a quick screening method. The iAs concentration was below 1% of total arsenic concentration for all the seaweed samples irrespective of using HG-ICPMS or HPLC-HG-ICPMS.