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The present study provides a comprehensive analysis of the biochemical composition (proximate composition, amino acids and fatty acids in gonad, digestive gland and muscle) of the cirrate octopod, Opisthoteuthis calypso, collected off the coast of Portugal. Protein and energy contents of O. calypso were significantly lower (p < 0.05) than those observed for coastal octopods, suggesting that the gelatinous musculature of the cirrate octopus may not be a direct consequence of food limitation, but rather associated with reduced selective pressure for strong swimming ability in the deep sea. Moreover, principal component analyses of fatty acid (FA) data clearly separated coastal octopods from O. calypso. Saturated FA biomarkers (namely 16:0, 17:0, 18:0) and monounsaturated FA 22:1 suggest a higher phytodetrital influence on diet of O. calypso. A clear separation between groups was also observed with amino acid (AA) data. However, essential AA and non-essential AA designations (based on the flow of carbon through biochemical systems) do not necessarily provide an accurate picture of the origins of amino nitrogen in the deep-sea environment. Consequently, the interpretation of the present data is a challenging task but opens a new window of opportunity to unravel new trophic biomarkers in the deep sea., Introduction There is no terrestrial equivalent to the extensive, cold, and dark deep-sea environment, and its distinctiveness dictates pervasive biochemical and physiological adaptations (e.g. Childress 1995; Seibel et al. 1997, [...]

Efforts have been made to find natural, highly nutritious alternatives to replace fish meal (FM) and fish oil (FO), which can simultaneously promote fish health and improve the nutritional quality of filets for human consumption. This study evaluated the impact of biofortified diets containing microalgae (as replacement for FM and FO), macroalgae (as natural source of iodine) and selenised yeast (organic source of selenium) on gilthead seabream growth, nutrient utilization, tissue composition and gene expression. A control diet (CTRL) with 15% FM and 5.5% FO was compared with three experimental diets (AD1, AD2, and AD3), where a microalgae blend (Chlorella sp., Tetraselmis sp., and DHA-rich Schizochytrium sp.) replaced 33% of FM. Diet AD1 contained 20% less FO. Diets were supplemented with Laminaria digitata (0.4% AD1 and AD2; 0.8% AD3) and selenised yeast (0.02% AD1 and AD2; 0.04% AD3). After feeding the experimental diets for 12 weeks, growth was similar in fish fed AD1, AD2, and CTRL, indicating that microalgae meal can partially replace both FM and FO in diets for seabream. But AD3 suppressed fish growth, suggesting that L. digitata and selenised yeast supplementation should be kept under 0.8 and 0.04%, respectively. Despite lower lipid intake and decreased PUFAs bioavailability in fish fed AD3, compared to CTRL, hepatic elovl5 was upregulated resulting in a significant increase of muscle EPA + DHA. Indeed, filets of fish fed AD2 and AD3 provided the highest EPA + DHA contents (0.7 g 100 g–1), that are well above the minimum recommended values for human consumption. Fish consuming the AD diets had a higher retention and gain of selenium, while iodine gain remained similar among diets. Upregulation of selenoproteins (gpx1 , selk , and dio2) was observed in liver of fish fed AD1, but diets had limited impact on fish antioxidant status. Overall, results indicate that the tested microalgae are good sources of protein and lipids, with their LC-PUFAs being effectively accumulated in seabream muscle. Selenised yeast is a good fortification vehicle to increase selenium levels in fish, but efforts should be placed to find new strategies to fortify fish in iodine. [ABSTRACT FROM AUTHOR]

Effects of different brines containing high concentration of calcium chloride, magnesium chloride, and potassium chloride on the chemical microbial (total viable counts, total coliforms, enterococci, and staphylococci), and sensory quality of salted cod, were studied. It was found that in the assayed concentrations, CaCl, MgCl, and KCl can be used in the brining of cod without adversely affecting the microbiological and sensory quality of the salted cod.

The antioxidant activity of fish protein hydrolysates may change in the digestive tract during the human gastrointestinal digestion depending on their preparation conditions. Thus, the objective of this study was to assess the antioxidant properties of Cape hake hydrolysates prepared by three different methods ( HPH-A, HPH-B and HPH-C) and the effect of their in vitro gastrointestinal digestion on their antioxidant properties. HPH-A showed the highest reducing power, while HPH-B and HPH-C exhibited the highest OH antiradical activity. Fe2+-chelating activity was similar for all hydrolysates, but HPH-C had a higher Cu2+-chelating activity comparable to that of EDTA. The in vitro gastrointestinal digestion of hydrolysates caused a decrease in the DPPH inhibition, but an increase in scavenging ABTS in all hydrolysates. Copper- and iron-chelating activities increased after digestion of hydrolysates. The results showed that the gastrointestinal digestion of HPHs generally increased their antioxidant properties. [ABSTRACT FROM AUTHOR]

The bioaccessibility of total lipids and fatty acids (FA) in raw and grilled gilthead seabream (Sparus aurata) was determined using an in vitro digestion model. The particular impact of grilling on the FA profile of seabream was also studied. In addition, the influence of lipid class on the bioaccessibility of each FA was analysed. Grilling did not change the relative FA profile, and only the absolute values were altered. However, the relative FA profile varied across lipid classes, being more dissimilar between TAG and phospholipids. Long-chain SFA and PUFA seemed to be less bioaccessible. Moreover, grilling reduced bioaccessibility of protein, fat and many FA, with the highest reductions found in PUFA such as the DHA. Strong evidence supporting a predominantly regioselective action of lipase during in vitro digestion was found, and the impact of this phenomenon on FA bioaccessibility was assessed. [ABSTRACT FROM PUBLISHER]

BACKGROUND: The aim of this studywas to analyse the influence of desalting temperature, fish thickness and desalting time on themass transfer kinetics during the cod desalting process by physico-chemical analyses. RESULTS: Both water uptake and salt loss increased with increasing temperature (15 °C>10 °C>5 °C) up to 24h in 'thicker' pieces. The equilibrium achievementwas faster in 'thinner' pieces and alsowith increasing temperature. Longer desalting times at 10 °C can be a good practice to be used during cod desalting at an industrial scale in order to obtain commercial products with higher yields. The fastermass transfer during desalting of 'thinner' pieces appears to followthree periods as a result of diffusion of the components (water, NaCl, and soluble proteins) because of the concentration differences, and pressure gradients due to expansion/shrinkage of the proteinmatrix, which is dependent on theNaCl content. The refractive index can be used by industry as an indirect measurement to determine themoment at which the 'thicker' samples are near the ZNaCl = YNaCl equilibrium. CONCLUSION: Optimum combinations between the process variables analysed are essential in order to speed up the mass transfer kinetics during cod desalting at an industrial scale. [ABSTRACT FROM AUTHOR]

BACKGROUND To advise consumers and manufacturers regarding decreasing the time needed to desalt salted cod (a time-consuming process), there is a need to develop knowledge about quality changes at different desalting temperatures. The objective of this work was to evaluate the physico-chemical, microbiological and sensory quality changes and their causes during cod desalting at 5, 10 and 15 °C, using a cod/water ratio of 1:9 without water changes. The influence of slices with different thickness and different desalting times was also evaluated. RESULTS Desalting promoted a decrease in the levels of total volatile basic nitrogen, thiobarbituric acid reactive substances and free amino acids nitrogen ( FAA-N). The highest FAA-N values were found in 'thicker' samples desalted at 15 °C due to the higher proteolytic bacteria number observed in these samples, which activity compensated the leaching of soluble components to the desalting solution. The water uptake and the salt leaching out of the muscle found during the processes created conditions for the bacterial growth, contributing to the spoilage at 15 °C. Based on fresh odour and 'off'-flavours results, 'thicker' samples desalted at 15 °C after 72 h were close to spoilage and on microbial levels were spoiled. CONCLUSION In order to extend the shelf life and safety of cod desalted products, desalting at temperatures above 10 °C is not advisable. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

The effect of seasonal changes (summer versus winter) upon the quality of heat-induced gel products from farmed sea bass (Dicentrarchus labrax) was studied. Moreover, the effect of microbial transglutaminase addition (0.5%, w/w) on the quality was assessed. Fat content of gel products attained from sea bass grown during summer was higher (12.0% versus 7.6%). Textural properties of the gels from the summer fish were higher. Protein of gels from winter fish was less soluble in SDS + DTT (sodium dodecyl sulphate, SDS; dithiothreitol, DTT). Contrary to some literature, higher fat level may have played a protective role during processing. Accordingly, season via fat content variation had a strong effect on the gelling ability of heat-induced gels prepared from sea bass. [ABSTRACT FROM AUTHOR]

Farmed gilthead sea bream ( Sparus aurata), European sea bass ( Dicentrarchus labrax), rainbow trout ( Oncorhynchus mykiss) and turbot ( Psetta maxima) produced in Portugal were analysed in order to characterize their elemental composition. Atomic absorption (flame and cold vapour) and molecular absorption spectrometry techniques were used to determine all the studied elements. Similar patterns of macro, trace and ultra trace elements were observed for all fish species. The main elements were potassium (K), sodium (Na), phosphorus (P), magnesium (Mg) and calcium (Ca), followed by zinc (Zn), iron (Fe), copper (Cu), chromium (Cr), manganese (Mn) and nickel (Ni). Cadmium (Cd), mercury (Hg) and lead (Pb) concentrations, obtained in this study, allow concluding that these species do not present a hazard for human consumption. In addition, they contain almost all essential elements at concentrations sufficient to suit the dietary reference intake. Nevertheless, P. maxima nutritious trace element content is relatively low compared with the other three species. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea is the biggest marginal sea of the Earth and is at the centre of the life for several millions of people. Seafood is consumed widely in this region, with an average of 16.5 kg/capita/year, and one-fourth of the seafood supply comes from aquaculture activities. The Mediterranean aquaculture sector has expanded in recent decades. Production increased by 77% over the past decade reaching about 1.3 million metric tonnes in 2009. The total value of production was around 3700 million US dollars, representing 3.4% of the value of global aquaculture production. The growth of seafood demand in the Mediterranean is expected to increase in the future, especially in southern countries. Yet, during the 21st century, the Mediterranean basin is expected to observe: (i) an increase in air temperature of between 2.2°C and 5.1°C; (ii) a decrease in rainfall of between 4% and 27%; (iii) an increase in drought periods related to a high frequency of days during which the temperature would exceed 30°C; and (iv) an increase of the sea level of around 35 cm and saline intrusion. Moreover, extreme events, such as heat waves, droughts or floods, are likely to be more frequent and violent. This paper reviews the present status of Mediterranean aquaculture (e.g. production trends, main farmed species, production systems, major producing countries), the most relevant impacts of climate change on this sector (temperature, eutrophication, harmful algae blooms, water stress, sea level rise, acidification and diseases) and proposes a wide range of adaptation and mitigation strategies that might be implemented to minimize impacts. [ABSTRACT FROM AUTHOR]

The effects of microbial transglutaminase (MTGase; 0.5%, w/w) and high hydrostatic pressure (HHP) on the quality of protein gels from unwashed mince of hake (Merluccius capensis) trimmings were studied. MTGase incorporation improved texture. Protein solubility was lower for those gels containing MTGase, as a result of myosin heavy chain cross-linking. HHP improved texture. Pressure level was the most important HHP parameter, since higher levels (300 vs. 100 MPa) augmented gel strength (GS). A positive synergistic effect of MTGase and HHP was found for some properties, such as GS, yielding improved gels from a raw material that otherwise shows poor gelation. [ABSTRACT FROM AUTHOR]

In the past few decades, the major compelling force in the study of marine lipids has been the need of the developing aquaculture industry to understand the lipid nutritional requirements of farmed fish so as to optimize production. At present, there is also increased interest to include health-promoting nutrients (nutraceuticals) in farmed foods, such as conjugated linoleic acid (CLA). Conjugated linoleic acid, a group of positional and stereoisomers of linoleic acid (18:2), acts as a growth factor to promote a repartitioning of fat to lean, lower blood lipids, and shows anticarcinogenic, hypocholesterolaemic and anti-atherogenic properties. In the present paper, we discuss current knowledge of the role of CLA in animal physiology and health and review advances in its application in fish aquaculture. [ABSTRACT FROM AUTHOR]

The present study investigated the potential application of the bacteriophage (or phage) phT4A, ECA2 and the phage cocktail phT4A/ECA2 to decrease the concentration of Escherichia coli during the depuration of natural and artificially contaminated cockles. Depuration in static seawater at multiplicity of infection (MOI) of 1 with single phage suspensions of phT4A and ECA2 was the best condition, as it decreased by ∼2.0 log CFU/g the concentration of E . coli in artificially contaminated cockles after a 4 h of treatment. When naturally contaminated cockles were treated in static seawater with single phage suspensions and the phage cocktail, similar decreases in the concentration of E . coli (∼0.7 log CFU/g) were achieved. However, when employing the phage cocktail, a longer treatment time was required to obtain comparable results to those achieved when using single phage suspensions. When naturally contaminated cockles were depurated with phage phT4A in a recirculated seawater system (mimicking industrial depuration conditions), a 0.6 log CFU/g reduction of E . coli was achieved after a 2 h of treatment. When the depuration process was performed without phage addition, a 4 h treatment was necessary to obtain a similar decrease. By combining phage therapy and depuration procedures, a reduction in bivalves depuration period can be achieved for, thus decreasing the cost associated with this procedure and even enhance the quality and safety of depurated bivalves destined for human consumption. [ABSTRACT FROM AUTHOR]

As bivalve molluscs are filter feeder, often consumed raw or lightly cooked and are frequently cultivated in contaminated waters, they are implicated in food-borne disease transmission to human. The present study investigated the potential application of bacteriophage (or phage) phSE-2, phage phSE-5 and phage cocktail phSE-2/phSE-5 to decrease the concentration of Salmonella enterica serovar Typhimurium ( Salmonella Typhimurium) during the depuration of natural and artificially contaminated cockles ( Cerastoderma edule ). Cockles were artificially infected with 10 5 and 10 6 colony-forming units (CFU)/mL of S . Typhimurium in static seawater and infected group were treated with phages at four different MOI values: 0.1, 1, 10 and 100. Depuration in static seawater at multiplicity of infection (MOI) of 0.1 with single phage suspensions of phSE-2 and phSE-5 provided the best results, as it decreased by ~ 1.3 and 1.7 log CFU/g, respectively, the concentration of Salmonella spp. after a 4 h treatment. At a MOI of 0.1, the rate of inactivation with single phage suspensions was higher when compared with the results obtained using the phage cocktail. However, in naturally contaminated cockles treated in static seawater with single phage suspensions and phage cocktail phSE-2/phSE-5, similar decreases in cultivable bacteria concentration (~ 0.7–0.9 log CFU/g) were achieved after 6 h of treatment. When artificially contaminated cockles were depurated with phage phSE-5 in a recirculated seawater system (mimicking industrial depuration conditions), a 0.9 and 2.0 log CFU/g reduction of Salmonella spp. was reached after 4 and 6 h treatment. Once the depuration process was performed without phage, a 6 h treatment was needed to obtain a 1.1 log CFU/g reduction of Salmonella spp. Results indicated that combining phage biocontrol with depuration procedures enhance bivalve microbial safety for human consumption by improving decontamination efficiency, proving that this technology can be transposed to the bivalves industry. Moreover, this approach also displays the advantage of reducing the time required for depuration and consequently its associated costs. [ABSTRACT FROM AUTHOR]

Abstract: The effects of MTGase (5 g/kg, w/w) and dietary fibre (inner pea fibre, 40 g/kg, w/w, carrageenan, 10 g/kg, w/w, carrageenan + konjac flour, 10 + 10 g/kg, w/w) on heat-induced gels from sea bass (Dicentrarchus labrax) trimmings were studied. MTGase incorporation had a positive effect on texture: gel strength and force at rupture increased. MTGase reduced protein solubility, meaning greater protein aggregation, according to electropherograms. Pea fibre had no positive effects: texture was quite similar to that of the control products and WHC was reduced. Carrageenan addition had no deleterious effect upon the texture of the gels and made them harder and springier. Force at rupture (even without MTGase) and WHC were greatly improved. Combination of carrageenan and konjac further enhanced these effects. For those gels without MTGase, protein solubility in urea and urea + DTT was reduced by both fibres, suggesting a reduction of hydrogen bonding between proteins. [Copyright &y& Elsevier]

Abstract: A new concept was applied to fish products. Chemical reagents targeting specific chemical bonds were incorporated in to gel products for assessing the importance of non-covalent (sodium dodecylsulphate, 1.0%, w/w), disulphide (dithiothreitol, 0.2%, w/w) or transglutaminase-catalyzed (N-ethylmaleimide, 0.2%, w/w) bonding. These reagents acting as chemical probes were applied to the study of sea bass and hake protein gels and the effect of MTGase (0.5%, w/w). These reagents were valuable for reaching conclusions. The action of an endogenous cysteine TGase in hake products was detected. It was found that frozen storage and protein denaturation are fundamental not only for explaining differences between raw materials, but also seem to favour a different action mode of MTGase in each raw material. Moreover, this study may help to improve processed products, for instance, the positive interaction between MTGase and the disruption of disulphide bonds in hake gels may find a useful application through incorporation of cysteine + MTGase. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to determine the nutritional value of adult commercial cuttlefish, to develop a Quality Index Method (QIM) scheme, and to evaluate the application of some biochemical methods commonly used for freshness assessment of fish under ice storage. Additionally, shelf-life was to be determined based on both QIM and suitable biochemical methods. The nutritional value of the cuttlefish mantle in the first 24h and after 13 days was determined. Captured cuttlefish was composed (g/100g) by 16.60±0.10g protein, 0.09±0.01g fat, 79.55±0.14g moisture and 1.39±0.03g of ash. After 13 days of ice storage, cuttlefish was composed (g/100g) of 11.90±0.28g protein, 0.17±0.09g fat, 87.04±0.13g moisture and 0.52±0.01g of ash. Differences (p <0.001) were found in protein, ash and moisture but not in fat (p >0.05). These results seem to indicate that there is impregnation of the iced water into the mantle tissue promoting protein leaching with the melting ice. TVB-N and TMA-N displayed a similar increasing tendency, peaking beyond EEC regulations proposed maximum between the 9th and 10th days. The developed QIM scheme for cuttlefish was composed of 29 demerit points, divided into 4 attributes and 13 parameters. The calculated quality index (QI) evolved linearly with storage time in ice (QI=2.68×days in ice−0.61, R 2 =0.9866). Storage time could be estimated with an accuracy of±1 day, if five cuttlefish from each sample were included in the QIM assessment. The shelf-life was determined as 8±1 days by both type of methods (QIM and biochemical). However, the suitability of some biochemical methods to assess freshness need to be more thoroughly researched. [Copyright &y& Elsevier]

This study aimed to evaluate the impact of diets including increasing amounts (1, 2 and 4%) of an iodine-rich macroalgae, Saccharina latissima , on gene expression and fillet composition of commercial-sized rainbow trout. Liver and muscle expression of genes related to growth, iodine, oxidative stress, and lipid metabolism, and the fillet content of fatty acids, cholesterol, and vitamin D 3 were assessed. The highest kelp inclusion led to lower final body weight and HSI, without significant differences in mRNA transcription of genes involved in growth (ghr1 , ghr2 and igf1) or iodine metabolism (dio1 , thra , and thrb). A significant downregulation of an oxidative stress marker, gpx1b2 , was observed in fish fed 2% S. latissima , which might suggest the need for less endogenous antioxidants. Dietary inclusion of kelp impacted lipid metabolism, with a downregulation of fatty acid synthase, accompanied by a general decrease of fatty acids in fillet. The present study demonstrated that supplementation of diets with 1 or 2% S. latissima can be achieved without detrimental effects on rainbow trout final weight. Evidence suggest a lipid-lowering effect of diets that did not compromise fillet EPA and DHA concentrations, being 3.7 times above the recommended levels for human consumption. [ABSTRACT FROM AUTHOR]

Senegalese sole (Solea senegalensis) is a high-value commercial species with increasing importance in aquaculture. The aim of this work was to study the quality changes of this species during chilled storage under refrigeration, through sensory and chemical methods. In particular, the optimization of a quality index method (QIM) scheme was proposed as well as the definition of sensory and chemical quality criteria. A shelf life of 15 days was reported, and a QIM scheme based on a total of 22 demerit points (dp) was proposed. Biogenic amines were never detected, and the usual spoilage indicators, such as TVB-N and TMA-N, were not significantly produced during the period of sensory-acceptable quality (15 days). On the basis of the significant correlations (p<0.001) between sensory data and Ki values, a quality index (QI) 19 dp and a Ki>40% indicate unacceptable quality of iced Senegalese sole.