Valorization of recurrently discarded fish species in trawler fisheries in North-West Spain.

The progressive elimination of fish discards established by the European Union Council in 2013 has stimulated the valorization of flesh from discarded high-quality species with good protein functional properties but which frequently have excessive fish-bones, fat, strange flavours, soft texture, etc. The present study therefore focuses on valorization of the extracted muscle (minced muscle), from several fish species frequently discarded in north-western Spanish fisheries (Atlantic Ocean): Blue whiting (Micromesistius poutassou), Mackerel (Scomber scombrus), Red scorpionfish (Scorpaena scrofa), Pouting (Trisoreptus luscus) and Gurnard (Trigla spp.). Valorization of these discarded fish resources is a key objective for the survival of the fishery sector in this area. In this regard present study was planned to examine the behaviour of the mince during 6 months of frozen storage by means of physicochemical and sensory analyses, and to test consumer acceptance of three technologically different products (burgers, nuggets and structured fingers) prepared with fish mince from different species. Results indicated that protein aggregation started at the outset of frozen storage but progressed very slowly, with the exception of non-washed blue whiting and red scorpionfish minces. Moreover, during frozen storage lipid oxidation increased in all samples; the increase was with two objectives highest in minced mackerel, a fatty fish, but no rancid flavour was detected. All mince samples presented acceptable physicochemical properties and good sensory acceptability after 6 months of frozen storage. Acceptability of final products made with these minces was high in all cases. Burgers were more acceptable for consumers aged over 40 and fingers and nuggets more for younger people.

Anchovy mince (Engraulis ringens) enriched with polyphenol-rich grape pomace dietary fibre: In vitro polyphenols bioaccessibility, antioxidant and physico-chemical properties.

The aim of this study was to evaluate technological and antioxidant properties, including in vitro bioaccessibility of polyphenols, conferred on raw anchovy mince by the addition of polyphenol-rich grape pomace dietary fibre at different concentrations. For this purpose, headed and gutted anchovy was heat-flayed, deboned and mixed with 0%, 2%, 3%, 4% grape pomace dietary fibre. A significant increase (P<0.05) in the concentration of polyphenols and associated antioxidant capacity was detected when grape pomace dietary fibre was incorporated in a proportion of at least 2% of the final mixture. In vitro digestion showed that the higher the grape pomace dietary fibre content, the higher was the proportion of polyphenols reaching the large intestine. Additionally, it was observed that the ABTS (2,2'-azino-bis(3-ethylbenzo-thiazoline-6-sulfonic acid) assay seems to be more suitable for evaluating antioxidant capacity in this kind of samples than FRAP (Ferric Reducing Antioxidant Power) assay. Technological properties such as mechanical and water holding, as well as sensory scores, indicated excellent qualities and acceptability of all samples. Hence, given the good acceptance of these samples, it should be feasible to make fish products based on mince anchovy as a means of increasing dietary intake of polyphenols with antioxidant capacity, especially considering the high concentration of polyphenols bioaccessible in the large intestine.

Effect of selective breeding on collagen properties of Atlantic salmon (Salmo salar L.).

Collagen content and properties of skeletal muscle were studied among selected (FP) and unselected (WP) Atlantic salmon lines that were reared together to avoid any environmental effects. The FP group had significantly higher body weight at harvesting, softer texture and lower connective tissue yield compared with the WP group. The relative collagen fractions (acid, pepsin, insoluble) were similar, but the FP group had a greater abundance of amino acids involved in collagen triple helix conformation and stabilisation (Gly, Pro, Hyp and Hyl), whilst the Lys content was greater for the WP group, indicating a more aggregated collagen. The connective tissue denaturation temperature was lower for the FP group, coinciding with a lower degree of collagen self-assembly and intermolecular-crosslinks. It is concluded that selective breeding has resulted in lower connective tissue stability of Atlantic salmon fillets.

Collagen characteristics of farmed Atlantic salmon with firm and soft fillet texture.

The possible role of collagen in texture variations among Atlantic salmon (Salmo salar L.) grown under commercial conditions at a Norwegian farm was studied. The texture was determined instrumentally as the breaking strength, and collagen and its salt (SSC), acid (ASC), pepsin (PSC) and insoluble (IF) fractions were analysed in order to determine the collagen aggregation degree. The collagen solubility and its overall amino acid (AA) composition showed no correlation to the breaking strength, but a positive correlation was observed between the breaking strength and glycine (r=0.74) and alanine (r=0.87) contents of the PSC fraction. Salmon with high breaking strength had higher T(peak) (temperature of transition) and ΔH (enthalpy of transition), and the collagen seemed to have triple helix structures mainly stabilized by covalent associations as compared to salmon with low breaking strength. The glycosylation degree was also positively correlated to the breaking strength (r=0.88, p ≤ 0.05). It is concluded that firmness of salmon muscle was not related to the total amount of collagen in the muscle, but rather higher collagen stability.