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Samples of salted anchovies (Engraulis encrasicholus) were taken at different stages during industrial ripening. The changes of bacterial counts and biogenic amines (histamine, tyramine, agmatine, putrescine, and cadaverine) contents were studied throughout the process. Bacterial growth was generally inhibited during ripening, with the occurrence of Enterobacteriaceae spp., probably related to hygienic failures. The changes in biogenic amines showed a decrease concentration trend, except with putrescine. The salt-ripened anchovy fillets exhibited low bacterial load (0.01-1.85 log CFU/g) and moderate biogenic amine contents (1.05-33.5 mg/kg). Relevant amine quality indicators such as histamine and tyramine showed levels, respectively, lower than those of the regulation and recommendation. This study indicated also that samples of salt-ripened anchovy fillets can be considered as safe.

This work investigated the effect of the industrial and domestic processing, including the use of polyphosphates, in the amino acids profile of dried salted cod. Amino acids contents fluctuated throughout the processing. The loss of nutritional quality (e.g. decrease of glutamic acid and taurine) could be due to solubilization of free amino acids, peptides, and proteins in brine, in drained water during dry-salting, and also in the desalting water. Changes in the amino acids contents were also related with variations in moisture and salt contents of cod products. The use of polyphosphates also affected amino acids contents in wet salted cod, dried salted cod, and desalted cod. In general, fresh cod and desalted cod presented similar and well-balanced amino acids compositions, with high amounts of glutamic acid (2.5-2.8 g/100g ww), aspartic acid (1.6-1.8 g/100g ww), leucine (1.2-1.4 g/100g ww), and lysine (1.1-1.2 g/100g ww), while histidine had the lowest amino acid score. The data obtained can be used by nutritionists for more informed diet recommendations in response to consumer demand for healthy habits.

There is an intensive search for alternative sources of bioactive molecules, including carotenoids, due to their potent antioxidant activities. Some aquatic microorganisms, such as thraustochytrids...

19 pages, 1 figure, 5 tables.-- This is an open access article distributed under the Creative Commons Attribution License, Fish discards and by-products can be transformed into high value-added products such as fish protein hydrolysates (FPH) containing bioactive peptides. Protein hydrolysates were prepared from different parts (whole fish, skin and head) of several discarded species of the North-West Spain fishing fleet using Alcalase. All hydrolysates had moisture and ash contents lower than 10% and 15%, respectively. The fat content of FPH varied between 1.5% and 9.4% and had high protein content (69.8–76.6%). The amino acids profiles of FPH are quite similar and the most abundant amino acids were glutamic and aspartic acids. All FPH exhibited antioxidant activity and those obtained from Atlantic horse mackerel heads presented the highest 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, reducing power and Cu2+ chelating activity. On the other hand, hydrolysates from gurnard heads showed the highest ABTS radical scavenging activity and Fe2+ chelating activity. In what concerns the α-amylase inhibitory activity, the IC50 values recorded for FPH ranged between 5.70 and 84.37 mg/mL for blue whiting heads and whole Atlantic horse mackerel, respectively. α-Glucosidase inhibitory activity of FPH was relatively low but all FPH had high Angiotensin Converting Enzyme (ACE) inhibitory activity. Considering the biological activities, these FPH are potential natural additives for functional foods or nutraceuticals, Project SEAFOOD_AGE-“Smart and eco-innovative SEAFOOD processes and products for healthy AGEing” (EAPA_758/2018) from the INTERREG Atlantic Area funding programme

Marketing issues of small-sized meagre can be overcome with the development of fish hams. This study aimed to test high pressure processing (HPP) to promote gelation of meagre hams, as an alternative to the heat processing. It was also aimed to reduce microbial transglutaminase (MTGase) from the formulation of HPP hams. Meagre hams were subjected to HPP varying different pressure parameters. The water holding capacity (WHC) and folding properties of hams were not affected by HPP, compared with heat processed hams. Whiteness was lower in HPP hams, and values increased with pressure level. The best results were obtained at 350 and 500 MPa at 30 °C, which also enhanced the textural properties of hams. Meagre hams prepared with different contents of MTGase (0–5.0 g/kg) were subjected to HPP. This enzyme did not affect the WHC and the folding properties of hams within each condition tested. HPP hams can be prepared with lower levels of MTGase (2.5 g/kg), without compromising the textural properties of hams. The results showed that it is possible to produce meagre hams with good textural properties and to reduce the MTGase content using HPP, validating the use of this technology as an alternative to the heat-induced gelation.

This study aimed to optimize an ion-exchange chromatography method for an accurate quantification of phosphates. Coelution of nucleotides was detected following the quantification of small amounts of di- and trimetaphosphates in hake fillets. In some samples, triphosphates were added to the glaze ice, therefore, defrosting waters (glaze ice + drip loss of fillets) should be analyzed for an effective assessment of the use of phosphates in seafood. Even low amounts of adenosine 5′-diphosphate (ADP) and inosine 5′-monophosphate (IMP) triggered false positive results for P2O74− and P3O93−. Keeping the initial isocratic conditions for longer was crucial for the separation of ADP from P2O74− and of IMP from P3O93−. The improved method showed that in general, hake fillets did not have diphosphates, and trimetaphosphates were residual. Triphosphates were clearly added in only four defrosting waters, and in most of the remaining ones, diphosphates and trimetaphosphates contents corresponded to false positive results.

Formulation of diets according to fish amino acid (AA) qualitative requirements may improve fish growth. Two diets with different AA profiles were tested on 16-day-old meagre during 20 days. The first diet had an AA profile closer to meagre larval AA requirements (BAL), whereas the second had a different AA profile (UNBAL). Results showed that larvae fed the diet with higher similarities to the AA profile of meagre carcass had a higher final weight (19.8 ± 0.5 mg versus 13.4 ± 1.8 mg) and lower ammonia excretion after being fed (0.6 ± 0.1 ml/(g DW. larvae. h) and 0.8 ± 0.1 ml/(g DW larvae. h)). A higher mean fibre area was obtained in 36 DAH larvae fed the BAL diet (224.8 ± 33.3 μm2 versus 158.8 ± 34.5 μm2) as well as higher larval weight. When fibre area distribution was analysed, a higher frequency of larger fibres was observed in 36 DAH BAL larvae, suggesting that fibre hypertrophy had a higher importance in this treatment. In conclusion, this study shows that meagre larvae fed a diet with an AA profile closer to their requirements had lower nitrogen losses and higher final weight, as result of higher muscle hypertrophy.

High consumption of phosphates, particularly added inorganic phosphates, may be associated with several health problems and so comprehensive data on their content in food, especially seafood, is of utmost importance. This work aimed to characterize phosphates contents in seafood products from the Portuguese market. Almost 900 samples of unprocessed and processed species of crustaceans, molluscs, and fish were analyzed at the Portuguese Institute for the Sea and Atmosphere over a 15 years’ time period. Considering processed products, crab sticks presented the lowest average values of total phosphates, while salted and dry cod, hake and shrimp evidenced the highest variations. Phosphates contents in unprocessed samples varied among species, being the lowest and highest average values observed for octopus and sardine, respectively. New reference phosphate limits were defined which permits verifying if the legislation is followed with respect to phosphates added to seafood. Moreover, the reference conversion factor is not adequate for seafood, and thus new factors were proposed. Overall, the addition of phosphates has not been a current practice. Nevertheless, for an easier control and to avoid the need of laborious sampling to establish natural phosphates levels, it would be more appropriate to define limits with respect to total phosphates contents.

Phytochelatins (PCs) and monothiols and their relation with trace element concentrations were studied in three plant species from two Portuguese salt marshes. Belowground tissues showed always higher element concentrations, while enhanced values of monothiols were found in aboveground biomass. Glutathione was usually the most abundant monothiol. The concentration of total PCs was higher in leaves or stems than in roots of Halimione portulacoides and Sarcocornia perennis, while in Spartina maritima the highest concentrations were reported in large roots. PC2 was synthesized by all tissues and species and was higher in large roots of S. maritima. PC4 and PC5 were in high levels in small roots of S. maritima. PC2 was positively correlated with As, Zn and Pb. Although being the first evidence of PCs and monothiols in these species under natural conditions, our results do not point to a simple relationship with elements concentrations, suggesting a complex mechanism involved. Fil: Negrin, Vanesa Lorena. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Instituto Argentino de Oceanografía. Universidad Nacional del Sur. Instituto Argentino de Oceanografía; Argentina. Instituto Português do Mar e da Atmosfera; Portugal Fil: Teixeira, Bárbara. Instituto Português do Mar e da Atmosfera; Portugal Fil: Godinho, Rita M.. Instituto Português do Mar e da Atmosfera; Portugal Fil: Mendes, Rogério. Instituto Português do Mar e da Atmosfera; Portugal Fil: Vale, Carlos. Instituto Português do Mar e da Atmosfera; Portugal. Universidad de Porto; Portugal

Background: Abusive water addition to octopus has evidenced the need for quick non-destructive methods for product qualification in the industry and control of fresh commercial products in markets. Electric conductivity (EC)/pH and dielectric property measurements were selected to detect water uptake in octopus.; Results: A significant EC decrease was determined after soaking octopus in freshwater for 4 h. EC reflected the water uptake of octopus and the correspondent concentration decrease of available ions in the interstitial fluid. Significant correlations were determined between octopus water uptake, EC (R = -0.940) and moisture/protein (M/P) ratio (R = 0.923) changes. Seasonal and spatial variation in proximate composition did not introduce any uncertainty in EC discrimination of freshwater tampering. Immersion in 5 g L-1 sodium tripolyphosphate (STPP) increased EC to a value similar to control octopus. EC false negatives resulting from the use of additives (STPP and citric acid) were eliminated with the additional determination of pH. Octopus soaked in freshwater, STPP and citric acid can also be clearly discriminated from untreated samples (control) and also from frozen (thawed) ones using the dielectric properties. No significant differences in the dielectric property scores were found between octopus sizes or geographical locations.; Conclusion: Simultaneous EC/pH or dielectric property measurements can be used in a handheld device for non-destructive water addition detection in octopus. M/P ratio can be used as a reference destructive method. © 2017 Society of Chemical Industry.; © 2017 Society of Chemical Industry.

In view of references to adulteration by water addition and low yield of Octopus vulgaris after cooking, moisture and protein baseline contents and the kinetic of water uptake following processing and cooking were characterized in raw octopus from the Portuguese coast. Water addition and cooking losses were also evaluated in commercial products. Moisture and protein content and moisture/protein (M/P) ratio of unprocessed octopus (n = 265) were 80.7 g/100 g, 16.6 g/100 g and 4.9, respectively. Onboard and on land industrial processing were simulated by soaking in freshwater (1, 4 and 16 h), in 5 g/L sodium tripolyphosphate and 2 g/L citric acid (16 h). Freshwater soaked octopus increased in weight up to 17% after 4 h and M/P ratio to 7.3. Soaked samples for 16 h lost between 14% and 36% more weight after cooking. Citric acid induced one of the highest level of water uptake and the highest water loss after cooking. M/P ratio correlation with weight changes showed that can be used to follow water uptake after landing and industrial processing. Analysis of commercial samples evidenced that consumers are being defrauded. Commercial products showed weight increases up to 50.8% and cooking losses, in general, 20% higher than in unprocessed samples.

Starch, due to its thermoplastic capacity, is being explored for developing food packaging bioplastics. Nevertheless, it gives rise to brittle and hydrophilic materials. To overcome these drawbacks, in this work, the influence of potato peel phenolic extracts (PhE) on physicochemical and mechanical properties of starch-based films was studied. PhE conferred a yellowish coloration to the neat films, while maintaining their transparency. Moreover, contrary to the pristine materials, starch/PhE-based films showed water tolerance, became elastic and stretchable, and presented antioxidant activity (56–85% of ABTS•+ inhibition after 7 days). Smoked seabream fillet packaged with the films were well appreciated by an experienced sensory panel, showing pleasant smell and flavor. The golden color increase of fillets was highly-valued by the judges, as well as their lower succulence and higher stiffness in relation to the fillets packed with commercial plastic. Therefore, potato peel phenolics are suitable for developing starch-based films with enhanced performance for food packaging.

The objective of this study was to evaluate the effect of different sources of lipids in the diets of dairy cows on the intake and digestibility of nutritional fractions, and milk production and composition. The experiment was conducted in a 42-hectare area divided into eight paddocks covered with Brachiaria brizantha. Twelve crossbred Holstein × Zebu cows were distributed into three simultaneous 4 × 4 Latin squares. The treatments consisted of different sources of lipids, as follows: diet with no extra source of lipids; diet with cottonseed as the source of lipids; diet with soy oil; and diet with used frying soy oil. The intakes of dry matter, neutral detergent fiber, crude protein, total carbohydrates, and non-fibrous carbohydrates were similar for all diets. The use of lipid sources caused a decrease in the apparent digestibility of dry matter, neutral detergent fiber, non-fibrous carbohydrates, and crude protein. The levels of protein, lactose, and defatted dry matter were reduced with the use of lipid sources but did not affect milk production. The use of cottonseed, soy oil, and used frying soy oil as sources of lipids in diets for lactating cows at pasture do not improve milk production, and their use is therefore optional.

Changes in added polyphosphates throughout the processing of dried salted cod in industrial environment were evaluated. As consumers purchase both dried salted cod and desalted cod, domestic and industrial desalting processes were performed. After brining, total phosphates increased to 11.6 and 16.6 g P(2)O(5)/kg in cod processed with 3 and 6% of polyphosphates, respectively. During dry-salting, total phosphates decreased in both cases to ca. 5 g P(2)O(5)/kg, suggesting that most polyphosphates were drained with the water released. Cod with polyphosphates needed 85 h extra drying time to achieve regulatory moisture levels. After desalting, total phosphates values in dry weight indicate that phosphates were not removed during this processing step. Free phosphates, and in particular triphosphate contents, were higher in cods desalted following domestic procedures, in comparison with industrial desalting. This study demonstrates that the use of polyphosphates is not recommended for the production of Portuguese dried salted cod. These additives prevent water from being removed during the drying process, increasing the costs. Moreover, in contrast to what was assumed, part of polyphosphates is retained in the final product, even after the desalting process.

The effects of microbial transglutaminase (MTGase; 5 g/kg, w/w) and dietary fiber (40 g pea fiber/kg product and 20 g carrageenan + 20 g konjac flour/kg product) on heat-induced meagre (Argyrosomus regius) gels with 25 and 10 g salt/kg, w/w were analyzed.MTGase addition increased the magnitude of texture variables. Inner pea fiber had an increasing effect on gel texture. The combination of carrageenan and konjac hardened meagre gels (from 22.2 ± 1.4 to 47.3 ± 4.5 N) and enhanced water-holding capacity. Salt reduction with MTGase ensured a gelling quality similar to that of gels from Alaska pollock surimi.

High pressure processing (HPP) is a technology able to reduce microorganisms and to modify food functional properties. This study aims to investigate the effect of three pressure variables (pressure levels of 100–400 MPa, pressure holding time of 0–30 min, and pressurization rate of 8 and 14 MPa s− 1) in microbiological and physical analyses, and in myofibrillar proteins profiles in sea bass fillets. Pressurization rate induced changes in all parameters evaluated, although in a lesser extent than other variables. In general, the characteristics of fillets treated at 100 MPa were not different from non-treated samples. The magnitude of changes increased with pressure level (250–400 MPa) and holding time (0–30 min). In general, with the increase of pressure level and holding time, fillets become whitish, microbiological load and water holding capacity decreased, pH increased, and myofibrillar proteins with molecular weights below 30 kDa increased, whereas those with lower isolectric point values decreased. HPP can be a potential tool to process fillets due to the improvement in microbiological safety (about 2 log CFU g− 1 reduction in the treatment at 400 MPa–30 min), which might result in an extended shelf life. Industrial relevance High pressure processing is an interesting technology for food preservation due to its ability to reduce microorganisms and to modify food functional properties. This study brought new evidences about the effect of high pressure processing on sea bass fillets, namely in myofibrillar protein profiles (SDS-PAGE and IEF electrophoreses). Variables such as pressure holding time and pressurization rate, besides pressure level, are also important in the choice of high pressure processing conditions. The results also suggest that high pressure processing might delay the degradation of fish muscle. The advantages of products treated with high pressure processing can lead to new opportunities in the market, being important for the food industry.

New heat-induced gel products prepared from farmed meagre (Argyrosomus regius) and psyllium dietary fiber (DF; up to 4.0%, w/w) with reduced salt content (from 2.5 to 1.0%, w/w) were studied. The effect of chilled storage time (15 days vs. 1 day) was also measured. Psyllium DF worsened breaking force and deformation as well as springiness, but it did not affect the remaining textural properties and improved water holding capacity (WHC). Salt reduction from 2.5 to 1.0% (w/w) decreased breaking force and deformation, cohesiveness, and WHC. The textural, color, and WHC properties of heat-induced meagre gels were unaffected by chilled storage time. Results pointed to the feasibility of using psyllium DF addition up to 4.0% (w/w) as a strategy not only to improve nutritional value of the gel products, but also to countervail some of the negative effects of a lower salt content.

The trade of live bivalves is a complex chain (harvesting, depuration, transportation), where animals are affected by several stressors that reduce animal condition and promote mortalities, with the consequent economic losses. The aim of this study was to investigate the physiological responses (survival rates, condition index, breakdown products of ATP and glycogen content) of two bivalve species from the Tagus estuary, Venerupis pullastra (native clam) and Ruditapes philippinarum (exotic clam) during two days of depuration and subsequent transport in semi-dry conditions at two temperatures (4 and 22 °C) until reaching 50% lethal time (LT50). Depuration did not negatively affect both species, even enabling additional two day survival extension until attaining LT50. In contrast, transport was an important stressor, with temperature contributing greatly for mortality: R. philippinarum showed higher survival rates than V. pullastra, always reaching LT50 later, especially at 4 °C. The exotic clam survived nine days more at 4 °C, but only one day more at 22 °C than the native species. Nevertheless, native clams showed higher condition index and glycogen content, and also lower nucleotide K-value and adenylate energy charge than exotic clams. The best semi-dry transport conditions to maintain good physiological conditions and high quality of clams should be performed at low temperatures (4 °C).

The aim of this study was to evaluate the effect of high-pressure processing (HPP) on the quality of fresh sea bass fillets using two pressure levels (250 and 400 MPa; 5 min pressure holding time). Vacuum-packed fillets were used as control samples, and all fillets were stored under refrigerated conditions for 18 days. The microbiological, chemical, physical, and sensory parameters were followed. Both HPP treatments increased the microbiological shelf life of sea bass fillets. In day 14, control samples reached the upper acceptability limit (7 log colony-forming units (CFU) g−1), while fillets treated at 250 and 400 MPa had 3.2 and 1.4 log CFU g−1, respectively. In general, hydrogen sulphide-producing bacteria and Enterobacteriaceae loads were below the detection limit in HPP treatments. Results from nucleotide analysis indicate that HPP treatments reduced the conversion of inosine 5′-monophosphate to inosine. HPP also influenced fillet sensory characteristics. The most evident changes in fillets were the increase in whiteness, the loss of translucency, and a firmer consistency. The effect was more pronounced in the treatment at 400 MPa. Lipid oxidation increased in HPP-treated samples, being more accentuated in the treatment at 400 MPa. Instrumental smell intensity increased in both HPP treatments, though the sensory panel did not detect any rancid or other unpleasant odours. No effect was observed in the amount of volatile bases or in pH values. In conclusion, HPP treatments showed potential application for new fish product development with increased microbiological safety and shelf life, longer freshness, and unique characteristics (e.g. firmer and whitish).

The potential of using the unwashed mince of farmed meagre as raw material for the preparation of heat-induced gel products was assessed taking into account the effect of age (small size 2 kg meagre), lower salt levels (1.0%, w/w, vs 2.5%, w/w), and microbial transglutaminase (MTGase) incorporation (0.0%, w/w, vs 0.5%, w/w). Heat-induced gel products from >2 kg fish were of superior quality. Salt reduction from 2.5% to 1.0% (w/w) was detrimental for textural quality, particularly, of gels prepared from >2 kg meagre mince. MTGase addition improved texture. Moreover, MTGase incorporation led to a greater importance of non-covalent hydrophobic bonding.

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.

The effect of microbial transglutaminase (MTGase) and dietary fibre (DF) from pea and chicory on the dynamic rheological properties of protein paste were studied for hake, gilthead seabream, sea bass, and meagre. Meagre and gilthead seabream presented higher storage modulus ( G ′) and higher transition temperatures marking the various phases of thermal gelling. The incorporation of chicory DF in the formulations reduced G ′. It was found that high degree of protein denaturation enhanced gel hardness. On the other hand, low degree of protein denaturation produced gels with high deformability. In accordance to this, the gels of those species with lower protein unfolding at a given temperature benefited most from MTGase addition.

Summary Two groups of farmed meagre (Argyrosomus regius) sausages were studied regarding quality changes and antioxidant capacity during a 98-day storage experiment at 2 ± 2 °C. Control sausages contained 3.9% (w/w) of inner pea dietary fibre (IPDF) and the other group contained 0.9% (w/w) IPDF plus 3.0% (w/w) of antioxidant grape dietary fibre (AGDF). The control and AGDF meagre sausages presented a high nutritional value, given their low caloric content, fatty acid profile, amino acid composition and high DF content. Both products were remarkably stable over storage time. The AGDF had an effective antioxidant capacity, proven not only by the radical scavenging activity (90.0–91.0% vs. 82.1–85.4%) and reducing power (8.13–9.10 mg ascorbic acid equivalent g-1 vs. 4.16–4.24 mg ascorbic acid equivalent g−1) measurements, but also by the lower thiobarbituric acid reactive species (TBARS) values (0.78–1.10 vs. 1.50–2.08 mg malonaldehyde kg−1) over storage time. AGDF seemed to present antimicrobial effect, since on the 63rd day (beginning of significant microbial growth), the control sausages had more than 3 log CFU g−1 and AGDF sausages much

The production of heat-induced gels from raw materials with poor gelling ability remains a technical challenge, for which new solutions have been proposed. The addition to the gel batters of a cross-linking chemical agent, such as 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), may present a valuable tool for the improvement of gelling. Accordingly, a response surface methodology was used to optimize the conditions of EDC application, the EDC concentration (0.0–0.5 %, w/w) and the batters’ pH (4.5–7.5). Results showed that textural, colour, and water-binding properties of heat-induced hake gels were extremely sensitive to EDC content and pH. It was possible to find an optimal EDC level-pH binary common to the various studied parameters, a pH between 4.0 and 5.0 and an EDC concentration of 0.5 %, w/w. Moreover, this experimental work proved to be feasible the achievement of gel products of acceptable textural quality from frozen hake through EDC incorporation in optimal conditions.

The effect of farmed fish species (sea bream, Sparus aurata, versus sea bass, Dicentrarchus labrax) on the quality of heat-induced gel products was evaluated. Additionally, the effect of microbial transglutaminase (MTGase) incorporation (0.5%, w/w) into the gels on their quality was also assessed. Both sea bream and sea bass yielded gel products of high quality. The fat content of the gel products attained from sea bass was higher than that of those prepared from sea bream (7.6% vs. 6.1%). Therefore, fat gels prepared with unwashed mince from farmed fish species may present a great potential for the aquaculture sector because, besides adequate gelling ability, these gels have a higher nutritional value than commercial gels, especially given their high eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels. Moreover, MTGase improved textural quality and reduced protein solubility. The gel strength, cohesiveness, and rupture properties of sea bream gels were higher than those of sea bass gels (mainly for gels containing MTGase), thus indicating a higher textural quality. Sea bass proteins were less soluble than sea bream proteins. Different hypothesis were put forward concerning the protein phenomena underlying such differences between the two farmed fish species.

Hake protein biodegradable films containing different thyme oil levels (0.025, 0.05, 0.1 and 0.25 ml oil/g protein) were prepared and their physical, mechanical and antioxidant properties were studied. Dried proteins were solubilized at pH 11 with NaOH and glycerol (59% of protein content) was added as plasticizer. The addition of thyme oil levels reduced both the film thickness and water vapor permeability. Films were homogeneous and transparent with a yellowish color. The optical properties of films were not generally affected by the thyme oil addition. Any clear trend between the mechanical properties of biodegradable films and thyme oil added was observed. Hake protein films exhibited some antioxidant activity, which was improved by the addition of 0.25 ml of thyme oil/g of protein.

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.

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.

In order to obtain low salt fish products, the effects of the addition of 0.5% (w/w based on whole product, wp) MTGase and different levels (0.25%, 0.50%, 1.00% and 2.50%, w/w wp) of sodium chloride salt to heat-induced gels from farmed sea bass (Dicentrarchus labrax) trimmings were tested and compared with gels without salt and/or without MTGase. MTGase and salt addition, both, had a favourable effect on texture. However, only salt incorporation augmented water holding capacity (WHC). A synergistic effect was detected between MTGase and salt for several important textural properties, particularly, gel strength, which reached 64.3 ± 8.1 N mm, a value comparable to those of best quality surimi. Moreover, MTGase required addition of salt to the product for its effect to be felt, however only a minimal amount (0.25%, w/w wp) sufficed. In fact, the addition of MTGase enabled reduction in salt content to 1.0% (w/w wp), without significant loss of textural and overall quality.

Two ready-to-eat minced fish products from hake were developed, their proximate composition and fatty acid profiles determined and their quality changes followed during 3.5 months under refrigeration at 2 ± 1 °C and 10 ± 1 °C. These products contain dietary fiber and are innovative and healthy. The formulation was identical, except vegetable oil (VO), 5.6% (w/w) in one group and 2.7% (w/w) plus 2.9% (w/w) cod liver oil (CLO) in the other. CLO products had a higher ω3/ω6 ratio (0.54 ± 0.02 versus 0.08 ± 0.02) and ensured, per 100 g serving, the 500 mg recommended daily intake of eicosapentaenoic and docosahexaenoic acids. CLO products showed lower gel strength (p ≤ 0.05), however, other textural properties were similar to those of the VO group. Thiobarbituric acid reactive substances values were higher in CLO products. All groups presented acceptable sensory scores and no microbiological growth. During storage products became redder and less yellow, while seafood aroma and flavor declined and saltiness perception augmented. Temperature had a negative effect on sensory elasticity and instrumental texture.

BACKGROUND: The effects of microbial transglutaminase (MTGase; 5 g kg−1) and dietary fibre (inner pea fibre and chicory root inulin, 20 and 40 g kg−1) on gels from surimi made with Atlantic (Scomber scombrus) and chub mackerel (Scomber japonicus) were studied with the purpose of achieving a better understanding of the underlying phenomena and improving gels. RESULTS: MTGase addition improved textural properties (namely, cohesiveness increased from 0.19–0.41 to 0.59–0.72) and increased pH and water-holding capacity (WHC). Moreover, MTGase reduced the elastic and viscous modules and darkened gels; protein solubility declined, meaning greater protein aggregation, according to electropherograms. MTGase had no unequivocal effect upon the gels' microstructure. Pea fibre increased hardness (an increase of almost 60% with 40 g kg−1) and related parameters, the elastic and viscous modules and WHC. Pea fibre reduced extractable protein in sodium dodecyl sulfate and urea (in the absence of MTGase) as well. Scanning electron microscopy revealed different structures for gels containing pea fibre. Regarding inulin, it worsened textural quality and WHC. CONCLUSION: A combination of MTGase and pea fibre can improve a poor quality surimi. Copyright © 2009 Society of Chemical Industry

Effects of five ingredients on cod sausages' chemical composition, pH, colour, texture, and sensory attributes were analysed. Changed ingredients were pea protein (0 vs. 2 g/100 g sausage), carrageenan (0 vs. 1 g/100 g), sodium bicarbonate (0, 0.15, and 0.3 g/100 g), sodium chloride (1.2 vs. 2.3 g/100 g) and pork meat (0, 13.3, and 26.7 g/100 g). Sausages became more yellow, springier, and harder with pea protein incorporation. Carrageenan addition made products redder, harder, and springier but less elastic. Sodium chloride reduction produced harder, springier, and more cohesiveness, but it produced less salty and smoky sausages. Textural effects of sodium bicarbonate addition were similar. Pork meat substitution made sausages harder, springier, and more cohesive.

Alternative methods to the traditional spectrophotometric determination of the malondialdehyde-thiobarbituric acid (MDA-TBA) complex (method A) and to the overestimation of MDA levels in the TBA reaction have been develop for the evaluation of lipid oxidation in fish. In this study, two HPLC separation methods of the MDA-TBA (method B) and MDA-dinitrophenylhydrazine (MDA-DNPH) adduct (method C) were investigated and compared to the traditional spectrophotometric TBA test (method A) in samples of chilled fish (hake, sea bream and sardine). Detection limits were 0.16, 0.10 and 0.20 μM MDA and quantification limits were 0.23, 0.17 and 0.26 μM MDA, for methods A, B and C, respectively. Recovery of method B ranged between 100% and 108% and of method C between 90% and 112%. Method A presented low recovery levels (under 71%). Overall method performance followed the order HPLC method MDA-DNPH > HPLC method MDA-TBA > traditional spectrophotometric TBA test. Though showing a better accuracy and specificity, method C had, however, some disadvantages, a relatively high limit of detection (0.20 μM MDA) and a lower reproducibility at lower MDA contents in standards and samples. Nevertheless, these are not critical drawbacks for an application in routine fish analysis, given the high MDA concentrations in oxidised fish. The application of the modified HPLC methods in fish samples with different levels of MDA, showed that these methods are useful for the samples with low amounts of oxidation products, such as chilled hake as well as in samples with high levels of oxidation, like 15 days chilled stored sardine.

Summary Sardine (Sardina pilchardus) is a species that for its abundance assumes great importance in the Portuguese fishing sector. In order to contribute for a better utilisation of this species, the aim of this study was to investigate the effect of the pre-treatment with soluble gas stabilisation (SGS) (100% CO2 at 2 bar, during 15 and 30 min) on the quality and shelf-life of sardine fillets, packed in air (AP), vacuum (VP) and modified atmosphere (MAP: 5% O2/35% CO2/60% N2). During the chilled storage, the quality changes were evaluated by sensory evaluation, chemical and microbiological analysis. The total volatile basic nitrogen content remained almost constant, between 16 and 19 mg N/100 g muscle, during the storage period, for all samples. The TBARs values increased with storage time, for all batches and storage conditions. The application of SGS treatment to sardine fillets, resulted in a bacteriostatic effect, contributing to the improvement of the microbiological quality of fillets. Considering a sensory criteria, the shelf-life of SGS pre-treated sardine fillets was found to be 5 days in AP and MAP while in VP-treated fillets a shelf-life of 8 days was reported. At sensory rejection, sardine fillets presented a K-value of 30% in AP and MAP batches and 40% in VP batch.

Soluble gas stabilization (SGS) is a relatively recent methodology of active packaging that has been proposed to extend the shelf life of packaged fish. The aim of the present work was to study the effect of SGS applied at different extents (2 bars: 30 and 60 min) on the shelf life of sea bream and sea bass fillets packed in air during chilled storage. Quality changes were evaluated by sensory assessment, microbiological analysis (TVC), TBARs, pH value, TVB-N, and TMA-N. No significant extension of sensory shelf life was visible as a function of SGS treatment. The treatment of fillets in CO2 at 2 bars during 60 min had a positive effect on the microbiological shelf life of both species. On the other hand, TMA-N and TVB-N showed similar changes during storage period and were not affected by the CO2 treatment. Sea bream treated with SGS always presented higher TBARs than control samples. Nevertheless, oxidation of sea bream and in particular, of sea bass fillets, did not appear to be a significant ...

Summary The objective of this study was to determine the differences of sensory, microbiological and chemical quality in vacuum-packaged fillets of sea bream and sea bass previously submitted to soluble gas solubilisation (SGS) with 100% CO2, at 2 bar for 30 and 60 min and stored at chilled temperature for 15 days. Apart from pH value that showed a regular increase during chilled storage, the other chemical index [total volatile bases nitrogen (TVB-N), trimethylamine nitrogen (TMA-N) and thiobarbituric acid reactive substances (TBARs)] had showed to be poor indicators of changes in quality of products. Final TVB-N values ranged from 16.0 to 17.4 mg N per 100 g and from 17.3 to 19.4 mg N per 100 g in sea bream and sea bass, respectively. Sensory evaluation resulted as the most reliable parameter of quality decay. The results show that SGS treatment kept the initial quality of fillets for longer time, which was particularly visible on the sea bream fillets, thus contributing to an extension in 2–3 days of the shelf life. SGS had also a positive effect in the delay of microbial growth.

In order to develop a healthy low-fat fish sausage containing dietary fibre (DF), three fundamental changes were made to an ordinary pork sausage recipe: incorporation of 4% (w/w) of Swelite® (a DF obtained from inner pea), different levels of pork meat replacement (0%, 50% and 100%) by hake mince and the combination of varying amounts of Fibruline® (a DF obtained from chicory root) and hake mince (Fibruline: additional hake mince, 2.6:5.2, 5.2:2.6 and 7.8:0.0, % w/w) as a substitute for pork fat. It was found that the addition of Swelite to pork sausage favoured greater gel strength and hardness. On the contrary, increasing levels of pork meat replacement by hake reduced the sausages' gel strength and hardness. Finally, sausages without pork fat showed promising textural and colour parameters. High-Fibruline sausages were less cohesive and chewable than pork fat sausages (control), but also exhibited a greater gel strength. Low-Fibruline ones presented almost all textural properties similar to the control, with exception of hardness and gumminess. Therefore, regarding some key textural parameters, it was possible to produce low-fat fish sausages similar to the ordinary pork sausages.

Summary The inclusion of various levels of a microbial transglutaminase or a carrageenan additive to restructured hake products with or without dietary fibre (obtained from inner pea or chicory root) was studied. These experiments were aimed at producing technologically innovative restructured fish products with improved textural and colour properties. It was found that the addition of transglutaminase, up to 0.5% (w/w), favoured better textural properties, particularly, at 0.1% (w/w) level or above. On the other hand, restructured product with a dietary fibre content of 4% (w/w) and carrageenan addition, up to 2% (w/w), exhibited increased hardness. This can be particularly interesting for those products containing chicory root inulins as this fibre presented an adverse effect on hardness. Regarding colour, higher carrageenan contents caused a slight but significant colour change in the product, making it redder (for products containing Swelite and Fibruline) and more yellow (only concerning Swelite).

Ingestive behavior of lambs fed diets consisting of fresh sugarcane with urea, bagasse treated with calcium oxide, and urea ammoniated sugarcane bagasse supplemented with concentrate mixture in 50:50 ratio were evaluated. For this, 34 wethers Santa Inês in their growing phase, with an average age of 3.0 ± 0.6 months and a mean initial live weight of 17.8± 5.2 kg were used. The animals were distributed in a completely randomized design and subjected to visual observation periods of 5 days, for 24 h a day, during the experimental period. Dry matter (DM) intake and intake efficiency of DM were higher (P 0.05) for animals receiving fresh sugarcane with urea. The animals which were fed with bagasse treated with calcium oxide had higher (P 0.05) consumption of neutral detergent fiber, longer feeding and chewing time (P 0.05), and shorter (P 0.05) idling time. The time spent on chewing the ruminal bolus did not differ from one diet to the other (P 0.05). Grams of dry matter per ruminated bolus were similar among animals fed with fresh sugarcane and ammoniated bagasse (P 0.05) but lower (P 0.05) in animals fed with bagasse treated with calcium oxide. Rumination efficiency values, in grams of dry matter per hour, and grams of neutral detergent fiber per hour for all three diets were similar (P 0.05) to those found for feeding efficiency. The number of feeding and rumination periods was not affected (P 0.05) by diet. Based on the intake and ingestive behavior responses, the fresh sugarcane with urea compared to bagasse treated with calcium oxide and ammoniated bagasse was found to be the better alternative feed for use in lamb diets.

The effect of gamma-radiation (1, 5 and 10 kGy) and post-irradiation ice storage on horse mackerel (Trachurus trachurus) muscle proteins was studied using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and urea CleanGel isoelectric focusing (IEF). The irradiation doses of 1 up to 10 kGy used seem to have no significant effect on the proteins of this species. SDS-PAGE showed few changes of the number of bands present. Most noticeable about the electrophoretic patterns were: (i) the gradual decrease in the intensity of some protein bands, particularly that of the MHC and (ii) the absence of any increase in bands associated with low molecular weight fragments with the increase in the irradiation dose. Irradiated samples presented a new high molecular weight (HMW) band (220 kDa) with an intensity independent of the irradiation level, that might be used as a marker. The number of bands in urea CleanGel IEF did not change in both unirradiated and irradiated samples. In the basic section, where major myofibrillar proteins are present, bands’ intensity increased with irradiation dosage. At the end of ice storage period, more intense protein bands were detected in the lots irradiated at higher dosages. Results underline the possibility of irradiation treatment up to 10 kGy, if needed for extension of horse mackerel shelf life and safety.

Fresh Atlantic horse mackerel (Trachurus trachurus) were gamma irradiated at 1 and 3 kGy, and stored in ice for 23 days. Quality changes during ice storage at 0±1 °C were followed by sensory analysis and the determination of total viable count, histamine, cadaverine, putrescine, tyramine, agmatine, spermidine, trimethylamine and volatile basic nitrogen contents. The control lot had a sensory shelf life of 8 days, whereas those of the irradiated lots were extended by 4 days. TVC’s and levels of amines increased in all lots with storage time, their contents being significantly reduced by irradiation, even when the lower level (1 kGy) was used. Histamine in the irradiated lots was undetectable when the fish was spoiled at the end of 23 days, whereas in the control lot, the concentration did not exceeded the maximum allowed in fresh fish (100 mg/kg). Presumptive identification of microorganisms gave a majority aerobic or facultative Gram-negative anaerobic rods being Gram-positive bacteria circa 10–18% in irradiated samples. Chemical indices were shown to be unsuitable for the determination of the quality changes in irradiated fish.

The effectiveness of oxygen absorber on the shelf life of scaled and gutted seabream packed in air during 10 days chilled storage (∼ 5°C) was studied. The quality changes were evaluated by sensory, microbial and chemical methods. Absorbers reduced oxygen concentration by 54% within the first two days and levels attained 0.1% after 6 days of storage. Significant differences in K values were not observed between packed batches with and without O2 absorber. Positive effects of O2 absorber on the reduction of lipid oxidation and sensory attributes, mainly on the appearance, were observed.

The suitability and reliability of three electrophoretic methods of fish species identification, urea isoelectric focusing (IEF), sodium dodecyl sulfate poly-acrylamide gel electrophoresis (SDS-PAGE) and native IEF, were evaluated on formed fish fillets and high pressure fish flesh by a collaborative study among four institutes. By following optimized standard operation procedures, the protein patterns of processed fish were compared to patterns of raw reference samples. The method to use depended of the effect of processing on the protein pattern. The proteins obtained from formed products were not denatured and therefore any of the three methods proved to be adequate, with a preference for native IEF which had a better discriminatory power for the species used. The high pressure process altered the proteins, and so only urea IEF and SDS-PAGE methods could be used. For these products, the chosen method should then be the one with the better discriminating power for the species being examined.

A study on the effect of the vacuum level and leaching time on the washing of lean sardine (Sardina pilchardus) mince was carried out. An experimental design was performed according to the statistical model of central composite design of response surface methodology. Proximate composition, water-holding capacity (WHC) and soluble protein were determined in the mince. Lipid classes and fatty acids were further analysed in the minces and in the extracted solutions. The WHC was greatest in the mince washed at atmospheric pressure for 40 min, and corresponded to the lowest fat content. The highest soluble protein extraction was obtained at intermediate values of pressure (382 mmHg) and time of washing (20 min). The fat initial content (4.6 %) was reduced by approximately 50% and was significantly affected by extreme vacuum levels (4 mmHg and 760 mmHg) and longer washing periods. Triacylglycerols were extracted the most, mainly at intermediate pressure values and increased washing periods. Polar lipids were next in abundance and were not extracted during washing. Polyunsaturated fatty acids were the major group of fatty acids, with eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) the most representative, being predominantly extracted at extreme pressure levels and increased periods of washing. DHA was more abundant in the washed mince, whereas the level of EPA was proportionally higher in the emulsions.

Changes in the content of histamine (Him), tyramine (Tyr), agmatine (Agm), spermidine (Spd), putrescine (Put), cadaverine (Cad) and volatile basic nitrogen (VBN) were examined during the ice storage of blue jack mackerel irradiated at diferent levels (0, I, 2 and 3 kGy). The variation of these amines in white and dark muscle offish irradiated with 0 and 3 kGy was also investigated. The levels of Him, Tyr, Put, Cad and VBN increased with storage time and their production was significantly reduced by irradiation offish. Him content in the control lot exceeded the maximum allowed in fresh fish (100 g/k& after 7 days, while in the irradiated lots a maximum value of 54.16 mg/kg of Him was determined after 23 days. No significant diferences were determined in nonvolatile amine production in samples irradiated with 1, 2 and 3 kGy. Although there was a correlation between fish quality deterioration and both Him and other amine production in irradiated fish, the highest values detected in spoiledfish were considerably lower than the maximum levels allowed. Thus, since the production level of Him and other nonvolatile amines is irradiation dependent the use of these compounds as quality indices may not be appropriate. Nevertheless, it is evident that irradiation, even at the lowest level used, extends the ice storage shelf-life of blue jack mackerel.

The suitability and reliability of urea IEF and SDS-PAGE for the identification of cooked fish flesh was tested by a collaborative study among nine laboratories. Urea IEF was performed with CleanGels as well as with ImmobilineGels, and ExcelGels were used for SDS-PAGE, enabling all three types of gels to be run in the same flat bed electrophoresis chamber. By strictly following optimised standard operation procedures (SOPs), five unknown cooked samples had to be identified with each technique using a set of 10 raw reference samples. With urea IEF, only one out of 35 identifications was incorrect, and with SDS-PAGE a similar result was obtained. It was concluded that methods, as now developed, are suitable for checking the species declaration of fishery products.

A collaborative study was carried out in seven European labs with the aim of achieving a sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) standard operation procedure to identify fish species in raw and cooked samples. Urea and SDS-containing solutions were evaluated as extractants. Several preelectrophoretic operations--such as treatment with RNase/DNase, ultrafiltration and desalting--and up to ten types of gels and three SDS-PAGE systems were considered. The SDS-containing solution allowed a higher protein extractability than urea. Unlike urea extraction, SDS extraction seemed not to be influenced so much by the state of the sample (raw, cooked at 60 degrees C, cooked at 85 degrees C). Desalting, ultrafiltration or treatment with RNase/DNase did not improve the discriminatory power of the protein patterns. Commercial homogeneous 15% ExcelGels, especially when they were silver stained, yielded good results and afforded higher reproducibility, thus allowing a better matching of results among the laboratories participating in this collaborative study. Under the optimized technical conditions described above, all the fish species tested, either raw and cooked, yielded reproducible and discriminant species-specific protein patterns.

Changes in histamine (Him), cadaverine (Cad), putrescine (Put), agmantine (Agm) and volatile basic nitrogen (VBN) contents were examined in sardine, Atlantic horse mackerel, chub mackerel and Atlantic mackerel, during ice storage and storage at room temperature. Him formation as well as other amines varied greatly with species of fish and storage conditions. The levels of Him, Cad, Put and VBN increased gradually in all the fish species as decomposition progressed, regardless of storage temperatures. In iced fish, amine production was considerably reduced and Him concentration was, in general, lower than 100 mg/Kg. During ice storage amines increased slowly until day 7, after which a significant rise was detected. In comparison with the other fish species higher levels of Him, Cad and Put were determined in Atlantic mackerel. At room temperature Him, Cad and Put were produced at the highest concentrations in chub mackerel, followed by sardine, Atlantic mackerel and Atlantic horse mackerel. Him concentration maximum exceeded allowable limits for human consumption in the first three species after 24h of storage at room temperature. No correlation was observed for Him or other amine levels and the degree of fish decomposition. Thus, the use of Him or other amines as a freshness index of the studied fish species was not considered appropriate.

Summary The gelling properties of farmed meagre (Argyrosomus regius) mince mixed with linseed and/or psyllium fibres (up to 4.0%, w/w) were studied. The effects of chilled storage time (15 days vs. 1 day) and cold gelling (setting at 2 ± 2 °C) were measured. Linseed addition increased ω3 PUFA content and worsened the gel products' texture. Psyllium functional fibre addition had only a negative effect upon breaking force and deformation, not affecting the remaining textural properties and improving water-holding capacity (WHC) from 61–77 to 70–85%. The incorporation of 4.0% (w/w) psyllium seems to be advisable. Quality of heat-induced meagre gels was unaffected by chilled storage time. Production of an acceptable cold set gel is feasible provided that enough time is allowed for completion of the setting process. Overall results showed a potential for combining small-sized meagre (

High-pressure processing (HPP) is a technology of growing interest for food preservation, due to its ability to control the activity of degradative enzymes. The effect of three variables (pressure levels of 100, 250, and 400 MPa; pressure holding times of 0, 5, 15, and 30 min; and pressurization rates of 8 and 14 MPa/s) on the activity of the enzymes acid phosphatase, cathepsins (B and D), lipase, and calpains was studied using sea bass fillets as a case study model. Additionally, the effect of HPP on sarcoplasmic proteins was studied by SDS-PAGE and isoelectric focusing electrophoreses. The increase in pressure level and holding time decreased the protein concentration in sarcoplasmic extracts, and also the activity of calpains. As compared to nontreated samples, acid phosphatase activity was lower at 400 MPa, and for cathepsin D lower activities were observed at 100 and 400 MPa. The increase in pressurization rate increased the activity of cathepsin D, lipase, and calpains, although it was not always significant. In contrast, cathepsin B and lipase activities were less affected by HPP treatments. Electrophoresis separation of sarcoplasmic proteins showed that the intensity of many protein bands changed mainly due to pressure level and holding time. The results of this study suggest that HPP causes lysosomes disruption and also denaturation, aggregation, and fragmentation of sarcoplasmic proteins, and this evidence might be related to the decrease in enzymes activity especially at 400 MPa. In conclusion, HPP can be a potential tool to control the activity of degradative enzymes, which might prevent the softening of sea bass muscle due to autolytic reactions.