Optimal packaging and storage conditions for fresh tilapia fillets were established by evaluating sensory and microbiological changes, as well as monitoring physicochemical properties. Nile tilapia (Oreochromis niloticus) farmed in recirculation aquaculture system was filleted, deskinned, and packaged in air and 50% CO2/ 50% N2 prior to chilling and superchilling storage at 1 ° C and −1 ° C. Sensory analysis of cooked samples revealed a shelf life of 13–15 days for air-packaged fillets during storage at 1 ° C and 20 days at −1 ° C. At the end of shelf life in air-packaged fillets, total viable counts (TVC) and pseudomonads counts reached log 8 colony-forming units (CFU) g−1. In 50% CO2/ 50% N2-packaged fillets, the lag phase and generation time of bacteria were extended and recorded counts were below the limit for consumption ( <log 8 CFU g−1) after 23 days of storage at both 1 ° C and −1 ° C. However, modified atmosphere (MA) packaging negatively affected color characteristics of the fillets soon after packaging (day 6). Color is an important indicator of tilapia fillets quality and a major factor in influencing retail purchase decisions. In view of that, air packaged at −1 ° C storage temperature was the optimal condition for fresh tilapia fillets. Total volatile basic nitrogen (TVB-N) and trimethylamine (TMA) were not good indicators of spoilage of tilapia fillets in this study.
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A molecular biological analysis of Icelandic volcanic rocks of different compositions and glassiness revealed the presence of Actinobacteria as an abundant phylum. In outcrops of basaltic glass they were the dominant bacterial phylum. A diversity of Actinobacteria were cultured from the rocks on rock-agar plates showing that they are capable of growing on rock-derived nutrient sources and that many of the taxa identified by molecular methods are viable, potentially active members of the community. Laboratory batch-culture experiments using a Streptomyces isolate showed that it was capable of enhancing the release of major elements from volcanic rocks, including weathered basaltic glass, crystalline basalt and komatiite, when provided with a carbon source. Actinobacteria of a variety of other sub-orders were also capable of enhancing volcanic rock weathering, measured as Si release. However, most strains did not significantly increase the weathering of the silica-rich rock, obsidian. These data show that Actinobacteria can contribute to volcanic rock weathering and, therefore, the carbonate-silicate cycle. Given their ancient lineage, it is likely they have played a role in rock weathering for over two billion years.
o evaluate the accuracy and robustness of an extraction method, utilizing an alkaline-ethanolic solution and microwave heating, the certified reference material (CRM) TORT-2 was subjected to three different instrumental methodologies: high-performance liq-uid chromatography (HPLC), coupled with and without post-column hydride generation; inductively coupled plasma-mass spectrometry (ICP-MS); and HPLC-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). The three methods gave a consistentvalue of inorganic arsenic (As) which is near the mean value of the reported values in the lit-erature, which, however, range by a factor of 10. Inorganic As, defined here as all As speciesthat do not have an As – C bond, that is, the sum of arsenite and arsenate and any thiol-boundAs, was found to be less than 4 % of total As concentration in 12 samples of fish meal whensubjected to this extraction method followed by HPLC-ICP -MS. To date, there is no certifiedvalue of inorganic As in a seafood-based reference material to compare to in order to vali-date the findings. This illustrates the difficulties in quantitative determination of inorganic Asin seafood and the need for a reference material for inorganic As and proficiency tests inorder to introduce legislation for a maximum level of inorganic As in seafood and feed.
Purpose
The purpose of this study is to examine attitudes towards fish consumption, social pressure, fish preparation and cooking skills, sensory beliefs, health involvement and fish consumption in childhood as predictors of fish consumption among consumers in their early adulthood. While the impact of these factors on fish consumption has been examined to some extent among adult consumers, this is believed to be the first study where the focus is on people in their late teens and their early 20s.
Design / methodology / approach
A cross sectional sample of Icelanders between 17 and 26 years old (n= 1,735) responded to a questionnaire. Structural equation modeling was used to estimate the direction and strength of relationships between variables.
Findings
The paper finds that attitude towards fish consumption, social pressure and fish preparation and cooking skills were correlated to fish consumption. Sensory beliefs and health involvement were also correlated to fish consumption, but this relationship was mediated by attitudes. Finally, there was a relationship between fish consumption in childhood and fish consumption but that relationship was mediated by sensory beliefs and attitude.
Research limitations / implications
The number of external variables included in the model is limited and correlational methods were used to estimate the relationship between factors.
Originality / value
The decrease in fish consumption among young consumers is of concern. Understanding the role different variables play in their fish consumption habits can provide health authorities and managers in the fish industry with useful insights for strategies for increasing the intake of fish among young consumers.
Fish proteins isolated from by-products or low commercial / underutilized species using pH-shift process is a new source of proteins that may be used as wet or dried ingredients to develop value-added convenience foods. This paper reports the effects of freeze-drying on characteristics of fish protein isolates (FPI) from saithe (Pollachius virens) with or without lyoprotectants. Freeze-dried saithe mince from the same lot and without additives was used as a control. The resulting fish protein powders contained 71-93% protein, 1.5-3% moisture, 0-21% carbohydrate and 0.5-2% fat. Lipid oxidation (assessed by TBARS) of FPI powder groups was higher than that of fish mince powder. The results revealed that oxidation started during the pH-shift process and was increased by freeze-drying. Functional properties and sensory attributes were influenced by the advanced oxidation. However, the mince powder was less oxidized and had higher functional properties such as water binding capacity, gel forming ability, emulsification, foaming properties and color and lower sensory scores for rancid odor and flavor than the FPI powders. Further studies on how to prevent oxidation of fish flesh during pH-shift and drying processes are recommended.
An appropriate thermal insulation of fresh fish packaging can substantially reduce negative effects of poor temperature management in chill chains. The aim of the current study is to experimentally and numerically investigate the performance of two types of EPS (expanded polystyrene) boxes in protecting superchilled fresh fish products subject to temperature fluctuations, simulating conditions during transport. One EPS box type is a new improved version designed by utilizing numerical heat transfer modeling for minimizing the maximum product temperature during thermal load. This box weighed 11% less than the older box type. The performance of the boxes was evaluated by means of temperature monitoring and sensory evaluation. The thermal insulation of the new boxes was significantly better compared to the old boxes. According to sensory evaluation, storage in the new boxes resulted in approximately 2 days longer storage life. A satisfactory agreement between numerical results and experimental results was obtained.
The addition of an online post-column hydride generation (HG) step to the commonly used high-performance liquid chromatography inductively coupled plasma-mass spectrometry (HPLC-ICP-MS) setup for arsenic speciation proved to significantly improve the detection limits for the determination of inorganic arsenic (iAs) as arsenate in seafood samples, where the limit of detection and limit of quantification were found to be 0.0004 and 0.0014 mg kg−1, respectively with HG. HG as an additional step further added to the selectivity of the determination of the iAs species and increased the detection and quantification of low levels of iAs (<0.002 mg kg−1) in samples with complicated matrices.
This article describes the results of a study that tested the responses to 14 seafood concepts among young adults and families with young children in Denmark, Norway, and Iceland. This study was aimed at gaining insight into the evaluation of new seafood product concepts by individuals with low seafood consumption. Based on consumer-reported values and previous concept-testing, 14 seafood product concepts were tested by 296 consumers in a web-based experiment. Consumers' preferences depended on the size of fish, the presence of information, and the fish species offered. Young adult consumers evaluated the product concepts differently than parents of young children. Three consumer clusters, based on attitudinal variables, were identified explaining the differences in the evaluation of the product concepts. The outcome of this study will be used to develop a product for realistic in-home testing.
In vitro anti-plasmodial activity-guided fractionation of a diethyl ether extract of the liverwort species Marchantia polymorpha, collected in Iceland, led to isolation of the bisbibenzyl ether, marchantin A. The structure of marchantin A (1) was confirmed by NMR and HREIMS. Marchantin A inhibited proliferation of the Plasmodium falciparum strains, NF54 (IC50 = 3.41 μM) and K1 (IC50 = 2.02 μM) and showed activity against others protozoan species Trypanosoma brucei rhodesian, T. cruzi and Leishmania donovani with IC50 values 2.09, 14.90 and 1.59 μM, respectively. Marchantin A was tested against three recombinant enzymes (PfFabI, PfFabG and PfFabZ) of the PfFAS-II pathway of P. falciparum for malaria prophylactic potential and showed moderate inhibitory activity against PfFabZ (IC50 = 18.18 μM). In addition, the cytotoxic effect of marchantin A was evaluated. This is the first report describing the inhibitory effects of the liverwort metabolite marchantin A against these parasites in vitro.
Macrocyclic bisbibenzyls are a class of characteristic compounds, exclusively produced by liverworts. They are attracting increasing attention due to their wide range of biological activities, including antibacterial, antifungal, and antioxidant properties as well as cytotoxicity. Marchantin A is a cyclic bisbibenzyl that has previously been isolated from Marchantia polymorpha and other liverwort species and has been shown to exert cytotoxic effects. In the present study we found that the Icelandic M. polymorpha species produces marchantin A and through an in vitro cell growth inhibition assay, marchantin A was shown to induce a reduction in cell viability of breast cancer cell lines A256 (IC50= 5.5 µM), MCF7 (IC50= 11.5 µM), and T47D (IC50= 15.3 µM). The effect was considerably increased in all cell lines in a synergistic manner when the Aurora-A kinase inhibitor MLN8237 was added simultaneously. Fluorescence microscopy confirmed the antimicrotubular effect of marchantin A, and cell cycle analysis indicated enhanced cell division failure when combining this mitotic-spindle inhibitor with the checkpoint modulator.