A Cell-Based Assessment of the Muscle Anabolic Potential of Blue Whiting (Micromesistius poutassou) Protein Hydrolysates.

Blue whiting (BW) represents an underutilised fish species containing a high-quality protein and amino acid (AA) profile with numerous potentially bioactive peptide sequences, making BW an economic and sustainable alternative source of protein. This study investigated the impact of three different BW protein hydrolysates (BWPH-X, Y and Z) on growth, proliferation and muscle protein synthesis (MPS) in skeletal muscle (C2C12) myotubes. BWPHs were hydrolysed using different enzymatic and heat exposures and underwent simulated gastrointestinal digestion (SGID), each resulting in a high degree of hydrolysis (33.41-37.29%) and high quantities of low molecular mass peptides (86.17-97.12% <1 kDa). C2C12 myotubes were treated with 1 mg protein equivalent/mL of SGID-BWPHs for 4 h. Muscle growth and myotube thickness were analysed using an xCelligence™ platform. Anabolic signalling (phosphorylation of mTOR, rpS6 and 4E-BP1) and MPS measured by puromycin incorporation were assessed using immunoblotting. BWPH-X significantly increased muscle growth (p < 0.01) and myotube thickness (p < 0.0001) compared to the negative control (amino acid and serum free media). Muscle protein synthesis (MPS), as measured by puromycin incorporation, was significantly higher after incubation with BWPH-X compared with the negative control, but did not significantly change in response to BWPH-Y and Z treatments. Taken together, these preliminary findings demonstrate the anabolic potential of some but not all BWPHs on muscle enhancement, thus providing justification for human dietary intervention studies to confirm and translate the results of such investigations to dietary recommendations and practices.

Health risk assessment and differential distribution of Arsenic and metals in organs of Urophycis brasiliensis a commercial fish from Southwestern Atlantic coast.

The concentrations of As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Sr, and Zn were analyzed in muscle, gills, and liver of Urophycis brasiliensis from two Southwestern Atlantic catch areas (Brazil and Argentina). Additionally, the health risk of general and fishermen populations through fish consumption was estimated. The gills showed the highest concentrations of most of the elements, followed by the liver. With the exception of As, the muscle was the organ with the lowest concentrations of most elements. Levels of arsenic in muscle of U. brasiliensis were exceeded the maximum permissible levels for human consumption recommended by local and international guidelines. The target hazard quotients (THQs) and the carcinogenic risk (CR) showed no risk for individual and all elements. These results highlight the importance of arsenic speciation in U. brasiliensis muscle in order to generate more reliable risk estimates.

Tissue dynamics of potential toxic elements in the Pacific hake (Merluccius productus): distribution and the public health risk assessment.

This study aimed to establish the distribution of As, Cd, Pb, Cu, and Zn in the main tissues (muscle, liver, gonads, and gills) of the Pacific hake (Merluccius productus) from the northern Gulf of California to establish baseline bioavailability levels in the northern stock. The results for Pb and Cd were the lowest in the studied tissues (Pb < 0.005 mg kg-1 in the liver and gonads and 1.43 mg kg-1 for Cd in the liver), followed by levels of Cu and As (muscle > liver > gonads > gills) and Zn with the most abundant levels in all the tissues. The sex of the organisms was not a factor that influenced the bioaccumulation and distribution of the potential toxic elements (PTEs) nor total length, except for As in gills and Cd in muscle and the liver. Important interactions among Zn and non-essential elements were established. The Pacific hake intake of PTEs was probably through the diet via bioaccumulation of the elements in their prey and less by pollution of the water column. In the muscle, a major distribution and storage of As, Zn, and Pb were observed, but in the liver, higher loads were from Cd and Cu. The maximum tolerable weekly intake must be very high to be at health risk for the essential elements and Cd. However, the population might be at risk for Pb and As consumption if more than 124 g of M. productus in adults and 35 g in children are consumed per week. Further investigations are required to understand the dynamics of PTEs in M. productus as it could be proposed as a biomonitor species.

Bioaccumulation of mercury and selenium in tissues of the mesopelagic fish Pacific hake (Merluccius productus) from the northern Gulf of California and the risk assessment on human health.

With the aim of evaluating health risk to hake consumers, mercury and selenium were measured in muscle, liver, gonads, kidney, and gills of 62 specimens of Merluccius productus from northern Gulf of California. Means ± confidence interval (95% confidence level) concentrations (mg kg-1 wet weight) of Hg in tissues were: gonads (1.01 ± 0.25) > muscle (0.44 ± 0.06) > gills (0.29 ± 0.04) > kidneys (0.20 ± 0.07) > liver (0.02 ± 0.004). No significant differences between sexes were found for Hg. The distribution of mean concentrations of Se (mg kg-1 wet weight) were: kidneys (4.61 ± 1.27) > liver (1.66 ± 0.22) > gonads (1.66 ± 0.75) > gills (0.86 ± 0.04) > muscle (0.40 ± 0.09). Se in gonads showed a significant difference between sex (females > males). Positive significant correlations with total length (p < 0.05) and total weight (p < 0.05) were found in the same tissue for both morphological variables: Hg in muscle, Se in muscle and Se in liver. An excess of Se over Hg (molar ratio Se:Hg > 1) was found in all tissues. The Hazard Quotient health risk index was evaluated for humans that consume muscle and gonads. The recommended Hg safe intake for adults and children were 110.0 and 33.0 g week-1, respectively for muscle; for gonads weekly consumption portions of 35.0 and 14.0 g for adults and children represent no Hg risk. There was no risk of exposure to Se.

Arctic marine fish 'biotransformation toxicity' model for ecological risk assessment.

Oil and gas exploration and marine transport in the Arctic region have put the focus on the ecological risk of the possibly exposed organisms. In the present study, the impacts of sea ice, extreme light regime, various polar region-specific physiological characteristics in polar cod (Boreogadus saida) and their effects on xenobiotic distribution and metabolism are studied. A Bayesian belief network is used to model individual fish toxicity. The enzyme activity in the fish liver and other pertinent organs is used as a proxy for cellular damage and repair and is subsequently linked to toxicity in polar cod. Seasonal baseline variation in enzyme production is also taken into consideration. The model estimates the probability of exposure concentration to cause cytotoxicity and circumvents the need to use the traditionally obtained No Observed Effect Concentration (NOEC). Instead, it uses biotransformation enzyme activity as a basis to estimate the probability of individual cell damages.

Concentrations and Risk Assessment of Heavy Metals in Tissues of Walleye Pollock (Gadus chalcogrammus) Captured from the Northeastern Coast of Korea.

HIGHLIGHTS: All heavy metals, except Hg, were well accumulated in liver compared with muscle and gonads. Estimated daily intakes of heavy metals were within 2% of the provisional maximum tolerable daily intakes, Hazard quotients of heavy metals were less than 1.0. Appropriate intake control of G. chalcogrammus is necessary to protect human health in the future.

Freshness assessment of European hake (Merluccius merluccius) through the evaluation of eye chromatic and morphological characteristics.

The most commonly used method for fish freshness determination is the sensory inspection; alternative sensory methods such as the Quality Index Method (QIM), based on the significant sensory parameters of one specific species, have been recently suggested. Considering that most of the sensory parameters are based on chromatic and morphological visual impression, the set-up of an objective method using computer vision techniques is very promising. The objective of this research was to characterize the changes in eye chromatic and morphological characteristics of European hake (Merluccius merluccius) during 13 days of storage on ice, using a tailored computer vision technique and a 3D scanner. Results obtained by multivariate statistical analysis of the colour spectra of eye images and by the eye concavity index using a 3D scanner permitted to estimate fish unacceptability after 7 days of storage, in agreement with results obtained by QIM sensory analysis. Moreover, 1H NMR was used to evaluate the production of trimethylamine (TMA) and the Ki index, confirming a good correlation with eye chromatic and morphological features. This preliminary study showed the high potentiality of the developed method as a non-destructive technique for raw fish freshness characterization / prediction, being a promising approach to create a robust portable instrument for the evaluation of fish freshness in real transport and marketing conditions.

Effect of high-pressure processing pretreatment on the physical properties and colour assessment of frozen European hake (Merluccius merluccius) during long term storage.

Fish freshness is lost by autolytic degradation produced by endogenous enzymes. Frozen storage is one of the most used methods to preserve fish properties. However, protein denaturation has shown to be a major problem for frozen European hake (Merluccius merluccius), leading to texture losses and off-odour development. The aim of this work was to study the changes produced by high-pressure processing (HPP) before freezing on quality of frozen European hake stored at -21 °C for 12 months. The effect of HPP (150-450 MPa) on mechanical properties and expresible water was evaluated in raw and cooked fish samples. The effect on colour (L*, a* and b*) was assessed only in raw fish. Results showed that HPP before freezing is beneficial to maintain expresible water in good levels up to 6 months. The luminosity significantly increased with pressure level. Textural profile of raw samples showed that HPP increased hardness, adhesiveness and springiness of frozen hake. Cooked samples were also affected by HPP, being the best results obtained at 300 MPa for 6 months of frozen storage. Overall, results showed that HPP improves the quality of frozen hake.

Assessment of burbot Lota lota (L. 1758) population sustainability in central European reservoirs.

A novel sampling scheme, using a combination of electrofishing, visual exploration by scuba divers, two types of fyke nets and longlines, was tested in four reservoirs (including their inlets and outlets) to monitor a population of burbot Lota lota. This was supplemented by fry trawling and vertical hydro-acoustics, to detect L. lota larvae in two deep reservoirs that have had a long-term stocking programme. The majority of the L. lota detected were juveniles, captured by electrofishing in the littoral zones of the reservoirs and in running waters. Older individuals were rarely captured with longlines or fyke nets in deeper zones or structured habitats within the reservoirs. A combination of multiple sampling methods provided an assessment of the whole population. Population establishment could not be demonstrated as the age structure of the sampled fish corresponded with that of the stocked fish. Low post-stocking survival, migratory behaviour, interactions with other species and warmer water temperatures are considered the potential drivers for unsuccessful establishment of L. lota populations in these reservoirs.

Production and assessment of Pacific hake (Merluccius productus) hydrolysates as cryoprotectants for frozen fish mince.

The aim of this study was to investigate application of fish protein hydrolysates (FPHs) as cryoprotectants for cod fish mince subjected to freeze-thaw abuse. Response surface methodology revealed little difference in cryoprotectant ability between FPHs produced from Pacific hake muscle within the range of conditions studied, namely Flavourzyme® enzyme/substrate ratio (E/S 1-4%), time (1-6h) and pH (5-7). When added at 4% or higher concentrations, FPH minimized expressible moisture and cook loss, while maximizing salt extractable protein from freeze-thaw abused fish mince, providing similar or better cryoprotection compared to an 8% sucrose-sorbitol blend, and a stabilizing effect of FPH on myosin was observed by differential scanning calorimetry. Sensory evaluation showed that addition of 8% FPH in fish ball products increased the perception of fishiness, saltiness, bitterness and firmness while decreasing moistness. FPH could be a viable alternative to the sugar-based cryoprotectants currently used for frozen fish products.

Determination of the Geographical Origin of All Commercial Hake Species by Stable Isotope Ratio (SIR) Analysis.

The determination of the geographical origin of food products is relevant to comply with the legal regulations of traceability, to avoid food fraud, and to guarantee food quality and safety to the consumers. For these reasons, stable isotope ratio (SIR) analysis using an isotope ratio mass spectrometry (IRMS) instrument is one of the most useful techniques for evaluating food traceability and authenticity. The present study was aimed to determine, for the first time, the geographical origin for all commercial fish species belonging to the Merlucciidae family using SIR analysis of carbon (δ13C) and nitrogen (δ15N). The specific results enabled their clear classification according to the FAO (Food and Agriculture Organization of the United Nations) fishing areas, latitude, and geographical origin in the following six different clusters: European, North African, South African, North American, South American, and Australian hake species.

Extending Vulnerability Assessment to Include Life Stages Considerations.

Species are experiencing a suite of novel stressors from anthropogenic activities that have impacts at multiple scales. Vulnerability assessment is one tool to evaluate the likely impacts that these stressors pose to species so that high-vulnerability cases can be identified and prioritized for monitoring, protection, or mitigation. Commonly used semi-quantitative methods lack a framework to explicitly account for differences in exposure to stressors and organism responses across life stages. Here we propose a modification to commonly used spatial vulnerability assessment methods that includes such an approach, using ocean acidification in the California Current as an illustrative case study. Life stage considerations were included by assessing vulnerability of each life stage to ocean acidification and were used to estimate population vulnerability in two ways. We set population vulnerability equal to: (1) the maximum stage vulnerability and (2) a weighted mean across all stages, with weights calculated using Lefkovitch matrix models. Vulnerability was found to vary across life stages for the six species explored in this case study: two krill-Euphausia pacifica and Thysanoessa spinifera, pteropod-Limacina helicina, pink shrimp-Pandalus jordani, Dungeness crab-Metacarcinus magister and Pacific hake-Merluccius productus. The maximum vulnerability estimates ranged from larval to subadult and adult stages with no consistent stage having maximum vulnerability across species. Similarly, integrated vulnerability metrics varied greatly across species. A comparison showed that some species had vulnerabilities that were similar between the two metrics, while other species' vulnerabilities varied substantially between the two metrics. These differences primarily resulted from cases where the most vulnerable stage had a low relative weight. We compare these methods and explore circumstances where each method may be appropriate.

Development of an SPME-GC-MS method for the specific quantification of dimethylamine and trimethylamine: use of a new ratio for the freshness monitoring of cod fillets.

BACKGROUND: Fish is a highly perishable food, so it is important to be able to estimate its freshness to ensure optimum quality for consumers. The present study describes the development of an SPME-GC-MS technique capable of quantifying both trimethylamine (TMA) and dimethylamine (DMA), components of what has been defined as partial volatile basic nitrogen (PVB-N). This method was used, together with other reference methods, to monitor the storage of cod fillets (Gadus morhua) conserved under melting ice. RESULTS: Careful optimisation enabled definition of the best parameters for extracting and separating targeted amines and an internal standard. The study of cod spoilage by sensory analysis and TVB-N assay led to the conclusion that the shelf-life of cod fillet was between 6 and 7 days. Throughout the study, TMA and DMA were specifically quantified by SPME-GC-MS; the first was found to be highly correlated with the values returned by steam distillation assays. Neither TMA-N nor DMA-N were able to successfully characterise the decrease in early freshness, unlike dimethylamine/trimethylamine ratio (DTR), whose evolution is closely related to the results of sensory analysis until the stage where fillets need to be rejected. CONCLUSION: DTR was proposed as a reliable indicator for the early decrease of freshness until fish rejection. © 2015 Society of Chemical Industry.

Assessment of Competition between Fisheries and Steller Sea Lions in Alaska Based on Estimated Prey Biomass, Fisheries Removals and Predator Foraging Behaviour.

A leading hypothesis to explain the dramatic decline of Steller sea lions (Eumetopias jubatus) in western Alaska during the latter part of the 20th century is a change in prey availability due to commercial fisheries. We tested this hypothesis by exploring the relationships between sea lion population trends, fishery catches, and the prey biomass accessible to sea lions around 33 rookeries between 2000 and 2008. We focused on three commercially important species that have dominated the sea lion diet during the population decline: walleye pollock, Pacific cod and Atka mackerel. We estimated available prey biomass by removing fishery catches from predicted prey biomass distributions in the Aleutian Islands, Bering Sea and Gulf of Alaska; and modelled the likelihood of sea lions foraging at different distances from rookeries (accessibility) using satellite telemetry locations of tracked animals. We combined this accessibility model with the prey distributions to estimate the prey biomass accessible to sea lions by rookery. For each rookery, we compared sea lion population change to accessible prey biomass. Of 304 comparisons, we found 3 statistically significant relationships, all suggesting that sea lion populations increased with increasing prey accessibility. Given that the majority of comparisons showed no significant effect, it seems unlikely that the availability of pollock, cod or Atka mackerel was limiting sea lion populations in the 2000s.

Ocean acidification may aggravate social-ecological trade-offs in coastal fisheries.

Ocean Acidification (OA) will influence marine ecosystems by changing species abundance and composition. Major effects are described for calcifying organisms, which are significantly impacted by decreasing pH values. Direct effects on commercially important fish are less well studied. The early life stages of fish populations often lack internal regulatory mechanisms to withstand the effects of abnormal pH. Negative effects can be expected on growth, survival, and recruitment success. Here we study Norwegian coastal cod, one of the few stocks where such a negative effect was experimentally quantified, and develop a framework for coupling experimental data on OA effects to ecological-economic fisheries models. In this paper, we scale the observed physiological responses to the population level by using the experimentally determined mortality rates as part of the stock-recruitment relationship. We then use an ecological-economic optimization model, to explore the potential effect of rising CO2 concentration on ecological (stock size), economic (profits), consumer-related (harvest) and social (employment) indicators, with scenarios ranging from present day conditions up to extreme acidification. Under the assumptions of our model, yields and profits could largely be maintained under moderate OA by adapting future fishing mortality (and related effort) to changes owing to altered pH. This adaptation comes at the costs of reduced stock size and employment, however. Explicitly visualizing these ecological, economic and social tradeoffs will help in defining realistic future objectives. Our results can be generalized to any stressor (or stressor combination), which is decreasing recruitment success. The main findings of an aggravation of trade-offs will remain valid. This seems to be of special relevance for coastal stocks with limited options for migration to avoid unfavorable future conditions and subsequently for coastal fisheries, which are often small scale local fisheries with limited operational ranges.

In vitro assessment of the multifunctional bioactive potential of Alaska pollock skin collagen following simulated gastrointestinal digestion.

BACKGROUND: Dietary mineral deficiency, hypertension and diabetes have become serious human health problems. Dietary approaches are increasingly being investigated to address these issues. Identification of food-derived biological peptides has become an important approach to control such diseases. Peptides generated from aquatic byproducts have been shown to possess biological activities. RESULTS: Significantly higher copper-chelating activity was observed on simulated hydrolysis of intact collagen. The collagen hydrolysate generated in the gastric stage exhibited moderate angiotensin-converting enzyme (ACE)-inhibitory activity with an IC50 value of 2.92 ± 0.22 mg mL(-1), which significantly decreased to 0.49 ± 0.02 mg mL(-1) after intestinal digestion. The dipeptidyl peptidase (DPP) IV-inhibitory potency of the collagen hydrolysate generated directly following simulated gastrointestinal digestion (SGID) (IC50 2.59 ± 0.04 mg mL(-1)) was significantly lower than that of the collagen tryptic hydrolysate (CTH) (IC50 1.53 ± 0.01 mg mL(-1)). The antioxidant activities of collagen and CTH using the ferric-reducing antioxidant power (FRAP) assay were 0.87 ± 0.10 and 1.27 ± 0.03 µmol Trolox equivalent (TE) g(-1) respectively after SGID. CONCLUSION: This study identifies collagen as a good and inexpensive substrate for the generation of biologically active peptides with potential applications as functional ingredients in the management of chronic illness and mineral deficiency problems.

Anisakid parasites in commercial hake ceviche in southern Chile.

The objective of this research was to determine the occurrence of anisakid nematode larvae in hake ceviche sold in restaurants in Valdivia (39°48'S, 73°14'W) and Niebla (39°49'S, 73°22'W), Chile. Between August and November 2012, 78 portions of ceviche were collected (6 from each of the 13 restaurants that sell this product). Each portion was weighed and divided into approximately 30-g samples, which were placed in petri dishes with 0.15 M NaCl. All samples were manually shredded and then examined with a stereomicroscope. Muscles of 41 southern hake (Merluccius australis), a fish sold fresh in Valdivia, also were examined by candling to determine the presence of anisakid larvae. The presence of Pseudoterranova larvae in ceviche sold in Chile was identified for the first time. The pH of ceviche ranges from 4.1 to 4.8, which favors the presence of viable anisakid larvae that tolerate the acid pH similar to that found in the stomach of their mammalian host. No significant differences (P > 0.05) in the prevalence, mean abundance, and mean density of anisakid larvae in ceviche were found between localities. Larvae were detected in ceviche from 3 of 6 restaurants in Valdivia and 4 of 7 restaurants in Niebla. Of the 78 examined portions of ceviche, 21.8% had larvae. The prevalence of viable larvae was 16.7 and 7.1% in the examined portions from Valdivia and Niebla, respectively. In the 41 hake muscle samples from Valdivia, the prevalence (4.9%), mean abundance (0.1), and mean density (0.03) was the same for Pseudoterranova and Anisakis larvae. No inspection processes or pretreatments are currently in place for raw fish to achieve safe conditions for ceviche in restaurants from Valdivia and Niebla.

Fast monitoring of species-specific peptide biomarkers using high-intensity-focused-ultrasound-assisted tryptic digestion and selected MS/MS ion monitoring.

A new strategy for the fast monitoring of peptide biomarkers is described. It is based on the use of accelerated in-solution trypsin digestions under an ultrasonic field provided by high-intensity focused ultrasound (HIFU) and the monitoring of several peptides by selected MS/MS ion monitoring in a linear ion trap mass spectrometer. The performance of the method was established for the unequivocal identification of all commercial fish species belonging to the Merlucciidae family. Using a particular combination of only 11 peptides, resulting from the HIFU-assisted tryptic digestion of the thermostable proteins parvalbumins, the workflow allowed the unequivocal identification of these closely related fish species in any seafood product, including processed and precooked products, in less than 2 h. The present strategy constitutes the fastest method for peptide biomarker monitoring. Its application for food quality control provides to the authorities an effective and rapid method of food authentication and traceability to guarantee the quality and safety to the consumers.

Dehydration of pollock skin prior to gelatin production.

UNLABELLED: Alaska pollock (Theragra chalcogramma) is the U.S.A.'s largest commercial fishery, with an annual catch of over 1 million tons. During pollock processing, the skins are discarded or made into fish meal, despite their value for gelatin production. The absence of gelatin-processing facilities in Alaska necessitates drying of the skins before transport to decrease the moisture content, but conventional hot-air drying is expensive. This study evaluated a less energy-intensive technology, the use of desiccants for reducing water weight in pollock skins prior to shipment. To ensure that the functional properties of gelatin obtained from dried pollock skins were not affected during desiccation, gelatins were prepared from each skin-drying treatment and compared with gelatin extracted from air-dried pollock skins. None of the desiccation treatments decreased the gel strength of pollock skin gelatin, nor were there major differences in gelling temperature or viscosity among the gelatin solutions. This suggests that pollock skins can be economically stabilized for transport to a gelatin-processing facility through the use of regenerable desiccants that are already common in the food industry. PRACTICAL APPLICATION: Pollock skins destined for gelatin production can be stabilized using chemical desiccants prior to shipment. The dehydration process does not harm the functional properties of gelatin, such as gel strength, gelling temperature, and viscosity. This research suggests that fish skins can be economically stabilized for transport to a gelatin-processing facility through the use of regenerable desiccants that are already common in the food industry.