The EU project BRAFO proposed a framework for risk – benefit assessment of foods, or changes in diet, that present both potential risks and potential benefits to consumers (Hoekstra et al., 2012a). In higher tiers of the BRAFO framework, risks and benefits are integrated quantitatively to estimate net health impact measured in DALYs or QALYs (disability- or quality-adjusted life years). This paper describes a general model that was developed by a second EU project, Qalibra, to assist users in conducting these assessments. Its flexible design makes it applicable to a wide range of dietary questions involving different nutrients, contaminants and health effects. Account can be taken of variation between consumers in their diets and also other characteristics relevant to the estimation of risk and benefit, such as body weight, gender and age. Uncertainty in any input parameter may be quantified probabilistically, using probability distributions, or deterministically by repeating the assessment with alternative assumptions. Uncertainties that are not quantified should be evaluated qualitatively. Outputs produced by the model are illustrated using results from a simple assessment of fish consumption. More detailed case studies on oily fish and phytosterols are presented in companion papers. The model can be accessed as web-based software at www.qalibra.eu.
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Heating and changes in pH often practiced during fish protein hydrolysis can cause lipid oxidation. The effect of natural antioxidants towards haemoglobin-mediated lipid oxidation during enzymatic hydrolysis of cod proteins was investigated. Different variants of a washed cod model system, containing different combinations of haemoglobin and natural antioxidants (l-ascorbic acid and Fuscus vesiculosus extract), were hydrolyzed using Protease P “Amano” 6 at pH 8 and 36 ° C to achieve 20% degree of hydrolysis. Lipid hydroperoxides and thiobarbituric acid reactive substances (TBARS) were analyzed periodically during the hydrolysis process. The in vitro antioxidant activity of the final products was investigated. Results indicate that oxidation can develop rapidly during hydrolysis and antioxidant strategies are preferable to produce good quality products. Oxidation products did not have an impact on the in vitro antioxidant activity of the hydrolysates. The natural antioxidants inhibited oxidation during hydrolysis and contributed to the antioxidant activity of the final product.
Although the tendency of Atlantic salmon Salmo salar to form differentiated populations among rivers and among tributaries within large river systems (> 100 km-long) is well documented, much less is known about population structure within small river systems (<30 km-long). In the present study, we investigated the genetic effects of straying of hatchery-reared salmon on population structure and genetic composition within the Ellidaár river system, a small system (21 km total length) in SW Iceland. We analyzed spatial and temporal variation of wild and domesticated samples (farmed and ranched; n = 931) using seven microsatellite loci. Estimates of population differentiation [FST, genetic tree (DA)] and Bayesian cluster analysis (STRUCTURE) revealed a significant population structure as well as relative long-term temporal stability of the genetic composition in the main river from 1948 to 2005. However, the genetic composition of the tributary populations was unstable and genetically homogenized in recent years. Wild-hatchery hybrids were detected during the influx of strays as well as a few years after, suggesting that introgression has changed the genetic composition of the wild populations. More investigations are needed in Iceland and elsewhere on possible fine-scale population differentiation and factors leading to it. Fine-scale population differentiation as observed in the present study has implications for the resolution with which harvest and habitat management of salmon should be conducted. In addition, farming and ranching operations should be located to minimize potential negative effects of strays on wild fish.
The food production industry has in recent years had to answer calls for environmentally friendly strategies and methods of communicating these effectively.This need is seen clearly in the fisheries sector where the concerns regarding the environment, ethical production and economic sustainability are driving forces for greater knowledge about the sustainability impact of a product or company. How these concerns and needs translate into requirements from the industry is poorly described in the literature. This study investigated these requirements within the framework of a theoretical tool which the stakeholders could use in the future. The results of the research carried out here show that stakeholders, through the fisheries supply chain, wish to use sustainability data for marketing purposes, internal benchmarking and improvement of environmental impact. The main challenge reported is to design a measurement tool that can be used in different conditions whilst still maintaining that integrity.
A soft thermo-reversible protein gel was studied with respect to failure. Flow curves recorded at constant shear rates revealed a dynamic yield stress σy, seen as a stress plateau below about 10 s−1. When a shear stress below σy was applied to fractured gels, they reformed after a time that increased with increasing stress and diverged at σy. Application of shear stress to fresh gels led to an initial elastic response followed by creep. Following this creep regime, the strain stagnated below the dynamic yield stress σy, while for σ > σy failure was observed after a time that increased with decreasing stress and diverged at σ = σy. The time-to-failure dependence on the stress for σ > σy, with two distinct exponential scaling regimes, agrees with existing proposed theories for the fracture of colloidal strands.
The identification of molecular structures of an arsenolipid is pivotal for its toxicological assessment and in understanding the arsenic cycling in the environment. However, the analysis of these compounds in a lipid matrix is an ongoing challenge. So far, only a few arsenolipids have been reported, including arsenic fatty acids (AsFAs) and arsenic hydrocarbons (AsHCs). By means of RP-HPLC-ICPMS / ESMS, we investigated Capelin oil (Mallotus villosus) for possible new species of arsenolipids. Twelve arsenolipids were identified in the fish oil including three AsFAs and seven AsHCs. Among the AsHCs, four that were identified had protonotated molecular masses of 305, 331, 347, and 359 and have not been reported before. In addition, the compounds with molecular formulas C20H44AsO+ and C24H44AsO+ were found in low concentrations and showed chromatographic properties and MS data consistent with cationic trimethylarsenio fatty alcohols. Derivatization by acetylation and thiolation coupled with accurate mass spectrometry was successfully used to establish the occurrence of this new class of arsenolipids as cationic trimethylarsenio fatty alcohols (TMAsFOH).
Sea cucumbers are used as healthy food, traditional medicine and dietary supplement. Sulphated polysaccharides (sPS) from their body wall possess variety of biological activities; however the immunomodulatory effects of sea cucumber polysaccharides remain unknown. Three sPS fractions were isolated from orange-footed sea cucumber (Cucumaria frondosa) and their effects on DC maturation investigated. DCs, matured in the presence of high molecular weight FCF-1 (100 and 1000 /g / ml) with a monosaccharide composition of NANA, GlcNAc, Man, Gal, Fuc and GalNAc (40: 13: 12: 12: 9: 8: 3), secreted reduced levels of IL-10, IL-12p40 and IL-6 (only at 1000 /g / ml). Furthermore, allogeneic CD4+ T cells co-cultured with DCs matured with FCF-1 (100 /g / ml) secreted reduced levels of IFN-γ and increased levels of IL-17 than allogeneic CD4+ T cells co-cultured with DCs matured without FCF-1. These data suggest that FCF-1 can affect DC maturation leading to increased Th17 and reduced Th1 activity; thus, increasing the Th17-mediated defense against yeast and extracellular bacteria.
The gene encoding the amylolytic enzyme Amo45, originating from a metagenomic project, was retrieved by a consensus primer-based approach for glycoside hydrolase (GH) family 57 enzymes. Family 57 contains mainly uncharacterized proteins similar to archaeal thermoactive amylopullulanases. For characterization of these family members soluble, active enzymes have to be produced in sufficient amounts. Heterologous expression of amo45 in E.coli resulted in low yields of protein, most of which was found in inclusion bodies. To improve protein production and to increase the amount of soluble protein, two different modifications of the gene were applied. The first was fusion to an N-terminal His-tag sequence which increased the yield of protein, but still resulted in high amounts of inclusion bodies. Co-expression with chaperones enhanced the amount of soluble protein 4-fold. An alternative modification was the attachment of a peptide consisting of the amino acid sequence of the mobile-loop of the co-chaperonin GroES of E.coli. This sequence improved the soluble protein production 5-fold compared to His6-Amo45 and additional expression of chaperones was unnecessary.
In this study, we present the discovery and characterization of a highly thermostable endolysin from bacteriophage Ph2119 infecting Thermus strain MAT2119 isolated from geothermal areas in Iceland. Nucleotide sequence analysis of the 16S rRNA gene affiliated the strain with the species Thermus scotoductus. Bioinformatics analysis has allowed identification in the genome of phage 2119 of an open reading frame (468 bp in length) coding for a 155-amino-acid basic protein with an Mr or 17,555. Ph2119 endolysin does not resemble any known thermophilic phage lytic enzymes. Instead, it has conserved amino acid residues (His30, Tyr58, His132, and Cys140) that form a Zn2+ binding site characteristic of T3 and T7 lysozymes, as well as eukaryotic peptidoglycan recognition proteins, which directly bind to, but also may destroy, bacterial peptidoglycan. The purified enzyme shows high lytic activity toward thermophiles, ie, T. scotoductus (100%), Thermus thermophilus (100%), and Thermus flavus (99%), and also, to a lesser extent, toward mesophilic Gram-negative bacteria, ie, Escherichia coli (34%), Serratia marcescens (28%), Pseudomonas fluorescens (13%), and Salmonella enterica serovar Panama (10%). The enzyme has shown no activity against a number of Gram-positive bacteria analyzed, with the exception of Deinococcus radiodurans (25%) and Bacillus cereus (15%). Ph2119 endolysin was found to be highly thermostable: it retains approximately 87% of its lytic activity after 6 h of incubation at 95 ° C. The optimum temperature range for the enzyme activity is 50 ° C to 78 ° C. The enzyme exhibits lytic activity in the pH range of 6 to 10 (maximum at pH 7.5 to 8.0) and is also active in the presence of up to 500 mM NaCl.
Nile tilapia (Oreochromis niloticus) farmed in recirculation aquaculture system (RAS) was filleted and packaged in 100% air and 50% CO2: 50% N2 modified atmosphere (MA) prior to storage at 1˚C and -1˚C for up to 27 days. Fillets were sampled regularly and analyzed for headspace gas composition, sensory and microbial changes. Shelf life varied with apparent relation to storage temperature, package atmosphere and microflora. Pseudomonads were reported as the main spoilage organisms in tilapia fillets during chilled storage conditions. Sensory analysis of cooked samples as well as microbial growth indicated fillets packaged in 100% air had a shelf life of 13-15 days during storage at 1˚C and 20 days at -1˚C. At the end of shelf life in 100% air packaged groups, TVC and pseudomonads counts reached log 7 colony-forming units g-1 in flesh. Whereas in 50% CO2: 50% N2 packaged fillets, the lag phase and generation time of bacteria was extended and recorded counts of <log 4 colony-forming units g-1 up to 27 days of storage at both 1˚C and -1˚C . However, 50% CO2: 50% N2 conditions restricted fillets shelf life to 23 days based on sensory changes mainly fillets color characteristics.