Influence of Cuttlefish-Ink Extract on Canned Golden Seabream (Sparus aurata) Quality.

Four different concentrations of an aqueous extract of cuttlefish (Sepia spp.) ink (CI) were introduced, respectively, into the packing medium employed during golden seabream (Sparus aurata) canning. The quality parameters of the resulting canned fish were determined and compared to the initial fish and the control canned muscle. An important effect of the CI concentration introduced in the packing medium was proved. The presence in the packing medium of a relatively low CI concentration (CI-2 batch) led to a lower (p < 0.05) lipid oxidation development (fluorescent compound formation), lower (p < 0.05) changes of colour parameters (L* and a* values), and lower (p < 0.05) trimethylamine values in canned fish when compared to control canned samples. Additionally, the two lowest CI concentrations tested led to higher average values of C22:6ω3, ω3/ω6 ratios, and polyene index. On the contrary, the use of the most concentrated CI extract (CI-4 condition) led to a prooxidant effect (higher fluorescence ratio value). In agreement with environmental sustainability and circular economy requirements, the study can be considered the first approach to a novel and valuable use of the current marine byproduct for the quality enhancement of canned fish. On-coming research focused on the optimisation of the CI-extract concentration is envisaged.

Concerted regulation of skeletal muscle metabolism and contractile properties by the orphan nuclear receptor Nr2f6.

BACKGROUND: The maintenance of skeletal muscle plasticity upon changes in the environment, nutrient supply, and exercise depends on regulatory mechanisms that couple structural and metabolic adaptations. The mechanisms that interconnect both processes at the transcriptional level remain underexplored. Nr2f6, a nuclear receptor, regulates metabolism and cell differentiation in peripheral tissues. However, its role in the skeletal muscle is still elusive. Here, we aimed to investigate the effects of Nr2f6 modulation on muscle biology in vivo and in vitro. METHODS: Global RNA-seq was performed in Nr2f6 knockdown C2C12 myocytes (N = 4-5). Molecular and metabolic assays and proliferation experiments were performed using stable Nr2f6 knockdown and Nr2f6 overexpression C2C12 cell lines (N = 3-6). Nr2f6 content was evaluated in lipid overload models in vitro and in vivo (N = 3-6). In vivo experiments included Nr2f6 overexpression in mouse tibialis anterior muscle, followed by gene array transcriptomics and molecular assays (N = 4), ex vivo contractility experiments (N = 5), and histological analysis (N = 7). The conservation of Nr2f6 depletion effects was confirmed in primary skeletal muscle cells of humans and mice. RESULTS: Nr2f6 knockdown upregulated genes associated with muscle differentiation, metabolism, and contraction, while cell cycle-related genes were downregulated. In human skeletal muscle cells, Nr2f6 knockdown significantly increased the expression of myosin heavy chain genes (two-fold to three-fold) and siRNA-mediated depletion of Nr2f6 increased maximal C2C12 myocyte's lipid oxidative capacity by 75% and protected against lipid-induced cell death. Nr2f6 content decreased by 40% in lipid-overloaded myotubes and by 50% in the skeletal muscle of mice fed a high-fat diet. Nr2f6 overexpression in mice resulted in an atrophic and hypoplastic state, characterized by a significant reduction in muscle mass (15%) and myofibre content (18%), followed by an impairment (50%) in force production. These functional phenotypes were accompanied by the establishment of an inflammation-like molecular signature and a decrease in the expression of genes involved in muscle contractility and oxidative metabolism, which was associated with the repression of the uncoupling protein 3 (20%) and PGC-1α (30%) promoters activity following Nr2f6 overexpression in vitro. Additionally, Nr2f6 regulated core components of the cell division machinery, effectively decoupling muscle cell proliferation from differentiation. CONCLUSIONS: Our findings reveal a novel role for Nr2f6 as a molecular transducer that plays a crucial role in maintaining the balance between skeletal muscle contractile function and oxidative capacity. These results have significant implications for the development of potential therapeutic strategies for metabolic diseases and myopathies.

The Presence of Bioactive Compounds in European Eel (Anguilla anguilla) Skin: A Comparative Study with Edible Tissue.

The presence of bioactive compounds in European eel (Anguilla anguilla) skin was studied. Proximate and lipid class compositions and analysis of the fatty acid (FA) profile (individual FAs; FA groups, i.e., saturated, monounsaturated, and polyunsaturated; FA ratios, i.e., polyunsaturated/saturated, ω3/ω6) were determined and compared to the composition of the eel muscle. As a result, higher (p < 0.05) levels of proteins (271.6 g·kg-1), lipids (38.0 g·kg-1), ash (27.7 g·kg-1), and ω6 FAs were observed in the skin tissue. Contrary, the muscle tissue showed higher (p < 0.05) moisture, ω3 FA, and ω3/ω6 ratio values. Regarding lipid classes, a higher (p < 0.05) proportion of phospholipids (111.1 g·kg-1 lipids), free sterols (104.7 g·kg-1 lipids), α-tocopherol (274.0 mg·kg-1 lipids), and free FAs (43.6 g·kg-1 lipids) was observed in the skin tissue. No differences (p > 0.05) between both tissues could be detected for triacylglycerol and FA group (saturated, monounsaturated, and polyunsaturated) values and for the polyunsaturated/saturated FA ratio. It is concluded that European eel skin, a by-product resulting from commercial processing, can be considered a valuable source for the food and pharmaceutical industries by providing value-added constituents such as proteins, lipids, ω3 FAs, phospholipids, and α-tocopherol.

Antioxidant Activity of an Aqueous Extract of Cuttlefish Ink during Fish Muscle Heating.

The antioxidant effect of cuttlefish (Sepia officinalis) ink (CFI) was analysed in the present study. A model system consisting of minced seabream (Sparus aurata) muscle and different concentrations of an aqueous extract of CFI was subjected to a heat (50 °C) treatment for 12 days. The effects of the CFI content and the heating time on lipid oxidation (conjugated diene (CD), conjugated triene (CT), and peroxide values and fluorescent compound formation), hydrolysis (free fatty acid content) development, and changes in the fatty acid (FA) profile (polyene index (PI), unsaturated FA content, ω3/ω6 ratio) were determined. The addition of the aqueous extract of CFI led to a lower (p < 0.05) development of lipid oxidation (CD, CT, and fluorescent compound determination) and to a higher (p < 0.05) retention of unsaturated FAs (PI determination). More important effects were found with increased CFI concentrations and at advanced heating times. However, a definite effect on lipid hydrolysis development (FFA value) could not be inferred. A new approach for the beneficial use of cuttlefish ink is presented. According to the direct relationship between rancidity stability and nutritional and sensory values, the present study provides a new strategy for the quality enhancement of thermally treated seafood.

Influence of Different Previous Frozen Holding Periods on the Canned Fish Quality.

The combined effects of thermal processing (i.e., sterilisation treatment) and the prior frozen storage time (3 or 6 months at -18 °C) on the quality loss in canned Atlantic horse mackerel (Trachurus trachurus) were determined. Thus, the sterilisation step led to a remarkable (p < 0.05) formation in the canned fish muscle of fluorescent compounds, free fatty acids (FFAs), and trimethylamine and an increase in the L* and b* colour parameters; meanwhile, a decrease (p < 0.05) in the total ω3 FA/total ω6 FA ratio and the a* colour value were detected. The prior frozen storage period led to an increased (p < 0.05) lipid oxidation (peroxide, thiobarbituric acid reactive substance, and fluorescent compound formation) and hydrolysis (FFA formation) development and to increased L* and b* colour values in the corresponding canned samples; additionally, a lower (p < 0.05) polyene index and phospholipid content were observed in canned fish previously subjected to frozen storage. In most indices, physico-chemical changes related to quality loss were found to be higher if the previous storage period was increased. According to the marked effects of the sterilisation step and the prior frozen storage period, the optimisation of such processing conditions is recommended to maximise the quality of canned horse mackerel.

Low-Toxicity Solvents for the Extraction of Valuable Lipid Compounds from Octopus (Octopus vulgaris) Waste.

This study focused on the recovery of valuable lipid compounds from octopus (Octopus vulgaris) by-products. Extraction conditions of total lipids (TLs), phospholipids (PLs), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) were optimized by employing a Simplex-Lattice design; for it, different relative concentrations of three low-toxicity solvents (ethanol, acetone, and ethyl acetate) were considered. The optimization process was also addressed in reference to fatty acid (FA) ratios (total polyunsaturated FAs/total saturated FAs and total ω3 FAs/total ω6 FAs). The variance analysis of multiple regression data demonstrated that the quadratic model was significant (p < 0.05) for TL, PL, and DHA values and the ω3/ω6 ratio. As a result, the following optimized values were obtained: 113.8 g·kg-1 dry by-products (TLs), 217.3 g·kg-1 lipids (PLs), 22.55 g·100 g-1 total FAs (DHA), and 3.70 (ω3/ω6 ratio). According to the model developed, optimized values were shown to correspond to the following relative solvent concentrations (ethanol/acetone/ethyl acetate): 0.46/0.00/0.54, 0.93/0.07/0.00, 0.83/0.17/0.00, and 0.64/0.00/0.36, respectively. Comparison to yields obtained by the conventional chloroform/methanol method was carried out. A novel strategy based on the employment of low-toxicity solvents is proposed for the extraction of valuable lipid constituents from octopus waste. A different solvent ratio would be necessary according to the lipid compound concerned.

Yield Enhancement of Valuable Lipid Compounds from Squid (Doryteuthis gahi) Waste by Ethanol/Acetone Extraction.

The study focused on the extraction of valuable lipid compounds from squid (Doryteuthis gahi) waste by a low-toxicity solvent mixture (ethanol/acetone, 50:50, v/v). The effect of the waste weight/solvent volume (WW/SV, g·mL-1) ratio and the number of extractions (NoE) on the total lipid (TL), phospholipid (PL), and tocopherol yields and on the fatty acid (FA) profile (eicosapentaenoic and docosahexaenoic acid contents; polyunsaturated FAs/saturated FAs and ω3/ω6 ratios) was investigated. As a result, an increased NoE led to an increased (p < 0.05) TL yield but a decreased (p < 0.05) proportion of PLs in the lipid extract. Additionally, a lower (p < 0.05) polyunsaturated FA/saturated FA ratio was detected by increasing the NoE. Some differences (p < 0.05) could be outlined as a result of increasing the WW/SV ratio; however, a definite trend for this extraction condition could not be concluded for any of the lipid parameters measured. Yield results were compared to those obtained by the conventional chloroform/methanol procedure. In order to attain an increased yield, the NoE required would depend on the polarity degree of the lipid molecule concerned. All ethanol/acetone extracting conditions tested led to remarkable yields for lipid compounds (PLs, α-tocopherol, ω3 FAs) and FA ratios with healthy, nutritional, and preserving properties.

Effect of Previous Frozen Storage and Coating Medium on the Essential Macroelement and Trace Element Content of Canned Mackerel.

The effect of previous frozen storage (-18 °C for 6 months) and different coating media (aqueous: water and brine; oily: sunflower, refined olive, and extra-virgin olive oils) on the essential macroelement and trace element content of canned Atlantic mackerel (Scomber scombrus) was studied. Previous frozen storage led to an increased (p < 0.05) content of canned samples of K (oil-coated samples) and Ca (all coating conditions) and to a decreased (p < 0.05) content of P (aqueous-coating samples) and S (water- and oil-coated samples). For trace elements, a content increase (p < 0.05) in Cu and Se (brine-canned samples) and Mn (water- and refined-olive-oil-coated samples) was detected in canned fish muscle with frozen storage. Concerning the coating effect, aqueous-coating samples showed lower (p < 0.05) Mg, P, S, K, and Ca contents than their corresponding oil-coated samples. For trace elements, lower average contents were found for Co, Cu, Mn, Se, and Fe in aqueous-coating fish muscle when compared to their counterparts coated in oily media. Content changes in the different elements in canned fish muscle are discussed based on interactions with other tissue constituents and modifications that such constituents undergo during processing (i.e., protein denaturation, liquor losses from the muscle, lipid changes).

Enhancement of Lipid Stability of Frozen Fish by Octopus-Waste Glazing.

The antioxidant properties of the liquor resulting from commercial octopus cooking were analysed for this study. Two different concentrations of octopus-cooking liquor (OCL) were tested as glazing systems during the frozen storage period (-18 °C for up to 6 months) of whole Atlantic horse mackerel (Trachurus trachurus). Compared to water-control glazing samples, an inhibitory effect (p < 0.05) on lipid oxidation development (the formation of thiobarbituric acid reactive substances and fluorescent compounds) was detected in frozen fish treated with the most concentrated OCL-glazing system. Additionally, a preservative effect (p < 0.05) on polyunsaturated fatty acids (measurement of polyene index) was also proved. However, no effect (p > 0.05) on the free fatty acid content and on the ω3/ω6 ratio was detected with the presence of the OCL in the glazing system. An increased lipid quality in frozen horse mackerel was established by including the OCL solution in the glazing system. According to previous research, the observed preserving properties were explained on the basis of the presence of antioxidant compounds in the cooking liquor. A novel and valuable combination of glazing processing and the employment of a marine waste substrate is proposed to enhance the lipid stability of frozen fish.

Hypothyroidism-associated immunosuppression involves induction of galectin-1-producing regulatory T cells.

Hypothyroidism exerts deleterious effects on immunity, but the precise role of the hypothalamic-pituitary-thyroid (HPT) axis in immunoregulatory and tolerogenic programs is barely understood. Here, we investigated the mechanisms underlying hypothyroid-related immunosuppression by examining the regulatory role of components of the HPT axis. We first analyzed lymphocyte activity in mice overexpressing the TRH gene (Tg-Trh). T cells from Tg-Trh showed increased proliferation than wild-type (WT) euthyroid mice in response to polyclonal activation. The release of Th1 pro-inflammatory cytokines was also increased in Tg-Trh and TSH levels correlated with T-cell proliferation. To gain further mechanistic insights into hypothyroidism-related immunosuppression, we evaluated T-cell subpopulations in lymphoid tissues of hypothyroid and control mice. No differences were observed in CD3/CD19 or CD4/CD8 ratios between these strains. However, the frequency of regulatory T cells (Tregs) was significantly increased in hypothyroid mice, and not in Tg-Trh mice. Accordingly, in vitro Tregs differentiation was more pronounced in naïve T cells isolated from hypothyroid mice. Since Tregs overexpress galectin-1 (Gal-1) and mice lacking this lectin (Lgals1-/- ) show reduced Treg function, we investigated the involvement of this immunoregulatory lectin in the control of Tregs in settings of hypothyroidism. Increased T lymphocyte reactivity and reduced frequency of Tregs were found in hypothyroid Lgals1-/- mice when compared to hypothyroid WT animals. This effect was rescued by the addition of recombinant Gal-1. Finally, increased expression of Gal-1 was found in Tregs purified from hypothyroid WT mice compared with their euthyroid counterpart. Thus, a substantial increase in the frequency and activity of Gal-1-expressing Tregs underlies immunosuppression associated with hypothyroid conditions, with critical implications in immunopathology, metabolic disorders, and cancer.

Antioxidant and Antimicrobial Effect of Biodegradable Films Containing Pitaya (Stenocereus thurberi) Extracts during the Refrigerated Storage of Fish.

This study focused on the quality loss inhibition of fish muscle during refrigerated storage. Two parallel experiments were carried out that were focused on the employment of pitaya (Stenocereus thurberi) extracts in biodegradable packing films. On the one hand, a pitaya-gelatin film was employed for hake (Merluccius merluccius) muscle storage. On the other hand, a pitaya-polylactic acid (PLA) film was used for Atlantic mackerel (Scomber scombrus) muscle storage. In both experiments, fish-packing systems were stored at 4 °C for 8 days. Quality loss was determined by lipid damage and microbial activity development. The presence of the pitaya extract led to an inhibitory effect (p < 0.05) on peroxide, fluorescent compound, and free fatty acid (FFA) values in the gelatin-hake system and to a lower (p < 0.05) formation of thiobarbituric acid reactive substances, fluorescent compounds, and FFAs in the PLA-mackerel system. Additionally, the inclusion of pitaya extracts in the packing films slowed down (p < 0.05) the growth of aerobes, anaerobes, psychrotrophs, and proteolytic bacteria in the case of the pitaya-gelatin films and of aerobes, anaerobes, and proteolytic bacteria in the case of pitaya-PLA films. The current preservative effects are explained on the basis of the preservative compound presence (betalains and phenolic compounds) in the pitaya extracts.

Enhancement of Lipid Stability and Acceptability of Canned Seafood by Addition of Natural Antioxidant Compounds to the Packing Medium-A Review.

Seafoods are known to include high contents of valuable constituents. However, they are reported to be highly perishable products, whose quality rapidly declines post-mortem, thus demanding efficient processing and storage. Among the traditional technologies, canning represents one of the most important means of marine species preservation. However, owing to the thermal sensitivity of the chemical constituents of marine species, remarkable degradative mechanisms can be produced and lead to important quality losses. The demand for better quality food makes the need for advanced preservation techniques a topic to be addressed continually in the case of seafood. One such strategy is the employment of preservative compounds obtained from natural resources. The current review provides an overview of the research carried out concerning the effect of the addition of bioactive compounds to the packing medium on the thermal stability of canned seafood. This review addresses the preservative effect of polyphenol-rich oils (i.e., extra virgin olive oil) and different kinds of products or extracts obtained from plants, algae and seafood by-products. In agreement with the great incidence of lipid damage on the nutritional and acceptability values during high-temperature seafood processing, this work is especially focussed on the inhibitory effect of lipid oxidation development.

Effect of Rigor Stage and Pressurisation on Lipid Damage, Total Volatile Amine Formation and Autolysis Development in Palm Ruff Stored on Ice.

The effect of the rigor stage (pre or post) and previous high-pressure processing (HPP; 450 and 550 MPa for 3 min) was checked during the storage on ice of farmed palm ruff (Seriolella violacea). Fish processed in pre-rigor conditions led to higher and lower levels (p < 0.05) of moisture and lipid contents in chilled fish, respectively, when compared to their counterpart samples processed in the post-rigor stage. Pre-rigor fish showed a higher (p < 0.05) quality level than post-rigor samples according to the assessment of the K value (59.0-92.1 and 70.3-96.3 ranges, respectively), fluorescent compounds (0.29-1.11 and 0.37-1.90 ranges, respectively), free fatty acids (FFA) (15.1-188.0 and 33.8-232.5 g·kg-1 lipids ranges, respectively), and total volatile amines (216.3-387.6 and 217.7-412.2 g·kg-1 muscle ranges, respectively). Pressure-treated fish showed higher (p < 0.05) quality retention than non-treated samples according to the formation of fluorescent compounds (0.29-0.86 and 0.85-1.90 ranges, respectively), FFA (15.1-50.6 and 58.9-223.5 g·kg-1 lipids ranges, respectively), and total volatile amines (216.3-250.3 and 351.1-412.2 g·kg-1 muscle ranges, respectively) and the evolution of the K value (59.0-77.2 and 86.9-96.3 ranges, respectively). The use of pre-rigor fish and previous HPP is recommended for the commercialisation of the current species as a fresh product.

Optimisation of Low-Toxicity Solvent Employment for Total Lipid and Tocopherol Compound Extraction from Patagonian Squid By-Products.

The extraction of total lipids and tocopherol compounds from Patagonian squid (Doriteuthis gahi) by-products (viscera, heads, skin, etc.), resulting from squid mantel commercialisation, was studied. An optimisation simplex-lattice design by employing low-toxicity solvents (ethanol, acetone, and ethyl acetate) was carried out taking into account their relative concentrations. The variance analysis of data showed that the quadratic model was statistically significant (p < 0.05); empirical coded equations were obtained as a function of the low-toxicity solvent ratios. The optimised lipid extraction was obtained by employing the 0.642/0.318/0.040 (ethanol/acetone/ethyl acetate) solvent ratio, respectively, leading to an 84% recovery of the total lipids extracted by the traditional procedure. In all extracting systems tested, the presence of α-, γ-, and δ-tocopherol compounds was detected, α-tocopherol being the most abundant. For α-, γ-, and δ-tocopherol compounds, the optimisation process showed that acetone extraction led to the highest concentrations in the lipid extract obtained (2736.5, 36.8, and 2.8 mg·kg-1 lipids, respectively). Taking into account the recovery yield on a by-product basis, the values obtained for the three tocopherols were included in the 88.0-97.7%, 80.0-95.0%, and 25-75% ranges, respectively, when compared to the traditional extraction. This study provides a novel and valuable possibility for α-tocopherol extraction from marine by-products.

Effect of Previous Frozen Storage, Canning Process and Packing Medium on the Fatty Acid Composition of Canned Mackerel.

This study addressed the fatty acid (FA) composition of canned Atlantic mackerel (Scomber scombrus). In it, the effect of prior frozen storage (6 months at −18 °C), different packing media (water, brine, and sunflower, refined and extra virgin olive oils), and canning procedure was investigated. As a result, the canning procedure led to a decrease (p < 0.05) in saturated FA (STFA) levels, an increase (p < 0.05) in polyunsaturated FA (PUFA) and total ω3 FA values, and higher PUFA/STFA and ω3/ω6 ratio values. Concerning the packing medium effect, the great presence of C18:2ω6 in sunflower oil led to high PUFA and PUFA/STFA values and low ω3/ω6 ratios when compared to other packing media. However, the high presence of C18:1ω9 in both olive oils tested did not lead to remarkable increases (p > 0.05) of this FA presence. Additionally, the presence of total ω3 FAs, C20:5ω3 and C22:6ω3 did not provide differences in canned fish muscle as a result of using different packing media. In all canned samples, ω3/ω6 values were included in the 8.2−10.8 range. Prior frozen storage did not have a substantial effect (p > 0.05) on the FA group (STFA, monounsaturated FA, PUFA, total ω3 FA) and FA ratio (PUFA/STFA and ω3/ω6) values.

Antioxidant Effect of Octopus Byproducts in Canned Horse Mackerel (Trachurus trachurus) Previously Subjected to Different Frozen Storage Times.

The effects on lipid damage in canned horse mackerel (Trachurus trachurus) of a prior frozen storage (−18 °C) period and the presence of an octopus (Octopus vulgaris) cooking juice (OCJ) in the packing medium were investigated. An increase of the frozen storage time favoured an increase (p < 0.05) of free fatty acid (FFA), peroxide, and thiobarbituric acid reactive substance contents and a decrease (p < 0.05) of the phospholipid (PL) value and polyene index. Furthermore, an increased presence of OCJ in the packing medium led to an inhibitory effect (p < 0.05) on fluorescent compound formation as well as to a retention (p < 0.05) of the PL and FFA compounds. Colour determination showed a substantial increase (p < 0.05) of L* and b* values in canned fish with previous frozen storage time. Nevertheless, this increase was partly reduced (p < 0.05) by the OCJ presence in the packing medium. It is concluded that previous holding time has led to an increased lipid oxidation development and loss of beneficial lipid constituents (i.e., PLs and polyunsaturated fatty acids). Remarkably, the presence in the packing medium of preservative compounds (i.e., antioxidants) included in waste juice obtained from octopus processing provided an effective tool for lipid preservation and quality enhancement in canned fish.

Low-temperature vacuum permeation of sodium tripolyphosphate and trehalose suppresses the denaturation of myofibrillar proteins in peeled shrimp (Litopenaeus vannamei) during frozen storage.

Phosphates and trehalose are widely accepted additives in animal muscle products. In this study, the effects of pre-soaking with sodium tripolyphosphate (STPP) and trehalose under vacuum permeation (VP) conditions on the physicochemical properties of shrimp muscle were evaluated over 120 d of frozen storage. The results indicate the STPP/trehalose-VP treatments significantly reduced the thawing loss and prevented changes in the texture, myofibrillar protein (MP) content, and Ca2+-ATPase activity of shrimp muscle during frozen storage compared with results of control and individual STPP or trehalose soaking treatments. The histological structure analysis revealed the permeated STPP/trehalose distinctly inhibited the dissociation of muscle fibers and reduced physical damage to connective tissues during storage. Furthermore, analysis of the thermal properties indicated STPP/trehalose treatment increased the T g ' values of shrimp muscle tissues, likely by restricting the mobility of water molecules in muscle tissues and embedding proteins in the glassy matrix. Thus, the physical destruction caused by ice crystal growth was greatly reduced, due to the absence of water molecules around muscle proteins during frozen storage. Accordingly, the combined STPP/trehalose-VP treatment significantly enhanced the stability of frozen shrimp, and the results support the application of traditional cryoprotective additives. The treated shrimp can be stored at comparatively higher temperatures with limited physicochemical reactions during frozen storage.

Cold-induced denaturation of muscle proteins in hairtail (Trichiurus lepturus) during storage: Physicochemical and label-free based proteomics analyses.

Physicochemical, proteomics, and bioinformatics analyses were conducted to investigate protein profiles in Trichiurus haumela under frozen (120 d) and chilled (6 d) storage. Springiness, chewiness, myofibrillar active sulfhydryl content, and Ca2+-ATPase activity significantly decreased, suggesting that cold stress altered muscle proteins. Compared with fresh hairtail (FH), 66 common differentially abundant proteins (DAPs) had lower abundances in chilled (3 d; CSH) and frozen (120 d; FSH) hairtail, including myosin binding proteins, filamins, actinin, troponin, and muscle-restricted coiled-coil protein. Gene Ontology (GO) annotation showed DAPs were mainly involved in cellular process, cellular anatomical entity, intracellular, and binding items. Eukaryotic orthologous group (KOG) analysis revealed that changes in cytoskeleton and energy production and conversion functions dominated during cold storage, degrading the myofibril and connective tissue structures and the physicochemical performance of muscle tissues. This study presents deep insights into the protein alternation mechanisms in hairtail muscle under cold stress.

Comparative Study of Bioactive Lipid Extraction from Squid (Doryteuthis gahi) by-Products by Green Solvents.

A novel approach of bioactive lipid extraction by different green solvents was carried out on squid (Doryteuthis gahi) by-products. By-products (viscera, heads, skin, tails, etc.), considered as a single product, were subjected to the following solvent systems: ethanol, acetone, ethyl acetate, 1/1 ethanol/acetone, 1/1 ethanol/ethyl acetate, and 1/1 acetone/ethyl acetate. Analyses carried out included lipid yield, lipid class content, and fatty acid (FA) composition. Results were compared to the lipid extract obtained by the traditional procedure (1/1 chloroform/methanol). Lipid yields obtained by green solvents led to a 33.4−73.2% recovery compared to traditional extraction; the highest values (p < 0.05) were obtained by ethanol-containing systems. Compared to the traditional procedure, ethanol systems showed an 85.8−90.3% recovery of phospholipid compounds and no differences (p > 0.05) in the ω3/ω6 ratio. Green-extracting systems led to higher average values for eicosapentaenoic acid content (15.66−18.56 g·100 g−1 total FAs) and polyene index (1.93−3.29) than chloroform/methanol extraction; differences were significant (p < 0.05) for systems including acetone and ethyl acetate. No differences (p > 0.05) were detected for docosahexaenoic acid content between the traditional procedure and green systems, with all values being included in the 31.12−32.61 g·100 g−1 total FA range. The suitability of EtOH-containing green systems for extraction of bioactive lipid compounds from squid by-products was concluded.

The Effect of Different Freshness of Raw Material on Lipid Quality and Sensory Acceptance of Canned Sardines.

We studied how storing fresh sardines (Sardina pilchardus) on ice for 0−15 days would affect lipid quality and sensory acceptance after the sardines were later canned. Average moisture and diacylglycerol contents showed a decreasing trend during storage time for sardines stored for to 0−10 days and an increasing trend for samples stored for 13−15 days. Total lipid and triacylglycerol average values increased with storage time of 0−10 days. In contrast, sardines stored for 13−15 days showed decreased values of lipids and triacylglycerols. Increased storage times also led to increased average saturated fatty acid (STFA) content and browning and decreased polyunsaturated fatty acid (PUFA) values and PUFA/STFA and ω3/ω6 ratios. Notably, the effect of storage time on PUFA/STFA and ω3/ω6 ratios and browning development was found significant (p < 0.05). Sensory descriptors revealed only slight quality differences with previous storage on ice for 0-10 days. In contrast, a substantial (p < 0.05) decrease (appearance and texture) was detected in samples corresponding to a 13−15-day period, such samples being considered unacceptable. Storage on ice not exceeding 10 days is recommended for sardines before being shipped to canneries for further processing. Furthermore, the use of efficient storage including preserving technologies would be desirable.