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Despite seafood being the primary source of long-chain omega-3 polyunsaturated fatty acids (PUFAs), the fatty acid (FA) contents of numerous exploited fish species remain unknown, partly due to the prohibitive costs associated with sourcing commercial fish fillets. We assessed whether fish by-products can reliably be used to estimate key nutritional FA contents in fillets by testing for consistent relationships between FA contents in fillet, and those in the breast, cheek, occiput, and tail tissue of three commercial coral reef fish species. Breast tissue was most suitable for estimating concentrations and proportions of FAs in the fillet due to strong and consistent relationships across FA types and species. In contrast, relationships between FA contents in the fillet and in other by-products were inconsistent across species and/or FA types. Through reducing research costs and food waste, utilising by-products will encourage FA research, particularly in tropical regions where omega-3 deficiency rates are highest. • Fish by-products can be used to estimate fatty acid contents of fish fillets. • Fatty acids in breast tissue had the strongest relationships with those in fillets. • These relationships were consistent across all species tested. • Fatty acids in other by-product tissues varied inconsistently with those in fillets. • Utilising by-products reduces costs associated with expensive fish fillets. [ABSTRACT FROM AUTHOR]

A boiled fish simulation system was constructed to explore the deodorization effect of main aroma compounds (MAC) on myofibrillar protein (MP) with main fishy compounds (MFC) during heating. The results showed that the MFC content of boiled fish was reduced by 63.10–78.10 % when boiled by heat-stable emulsions loading MAC. Specifically, adding linalool, anethole, and myrcene significantly elevated the free percentage of hexanal, heptanal, and 1-octen-3-ol after heating, while the free percentage of octanal and nonanal markedly increased by adding anethole and limonene. Molecular docking exhibited that MAC and MFC possessed co-binding sites with myosin. Linalool and anethole were competitively bound to MP through hydrophobic and hydrogen bonding sites, while myrcene and limonene were via hydrophobic interaction sites. Moreover, MAC-MP formed a relatively stable structure, exhibiting increased α-helix content and decreased surface hydrophobicity, which reduced the available sites for MFC binding, ultimately desorbed MFC (65.46 %–95.89 %). [Display omitted] • Heat-stable emulsions loaded with MAC markedly reduced fishy odor of fish fillets. • A simulation system mirroring the boiled fish preparation process was constructed. • MFC were desorbed 65.46 %–95.89 % by adding MAC. • MAC competitively bound to MP via hydrophobic and hydrogen bonding sites. • Hydrophobic interactions are the primary force between MP and MAC. [ABSTRACT FROM AUTHOR]

This study investigated the dietary effects and metabolic mechanisms of astaxanthin (Ast) in common carp (Cyprinus carpio). Supplementation with 100 mg/kg Ast resulted in a significant 19.83 % increase in growth. Data from the electronic tongue indicated that dietary Ast enhanced fillet sweetness while reducing bitterness and saltiness. Colorimetric and computer vision analyses showed a shift in fillet color toward yellow-red (amber) hue, with a* values rising by up to 59.93 % (redness) and b* values by 40.84 % (yellowness). Carotenoid quantification revealed that Ast was metabolized into violaxanthin (0.23 ± 0.07 μg/g) and neoxanthin (0.19 ± 0.05 μg/g), with this conversion reaching a plateau at 100 mg/kg. These carotenoids were key contributors to the observed color changes. Based on structural analysis and inverse docking, potential metabolic pathways for Ast conversion are proposed, including steps from Ast to violaxanthin and neoxanthin. In conclusion, dietary Ast improves the flesh quality of common carp. [Display omitted] • Astaxanthin in the diet enhances the growth of common carp. • Dietary astaxanthin enhances fillet sweetness and lowers bitterness, saltiness. • Dietary astaxanthin induces amber coloration in common carp fillets. • Common carp can metabolize astaxanthin into violaxanthin and neoxanthin. • Potential pathways for astaxanthin conversion in common carp are proposed. [ABSTRACT FROM AUTHOR]

This study investigated the changes in quality and volatile flavoring compounds in sturgeon fillets during refrigeration. Potential flavor compounds were identified using orthogonal partial least squares discriminant analysis (OPLS-DA) and gas chromatography– ion mobility spectrometry (GC-IMS). The results showed that TVB-N content, TBARS values, total colony counts, and K-value increased with prolonged refrigeration, reaching spoilage thresholds after approximately eight days. A total of 33 volatile compounds (including monomers and dimers) were detected in sturgeon fillets during different refrigeration periods, including aldehydes, alcohols, ketones, acids, esters, ethers, and other compounds. OPLS-DA further revealed flavor differences in sturgeon fillets across different refrigeration stages, identifying 18 distinct volatile compounds. Correlation analysis showed that trans-2-Pentenal, 2-methylpropanal, and glutaraldehyde were associated with pleasant odor to the frozen sturgeon fillets in the early stage, while hexane nitrile and thiazole were the main substances that caused unpleasant odors. • GC-IMS fingerprints visualize the flavor profile of sturgeon fillets at different stages of refrigeration. • OPLS-DA and VIP analysis identifies potential aroma biomarkers in sturgeon fillets at different freezing stages. • The 6th day of refrigeration was an important control point for flavor changes for sturgeon fillets. [ABSTRACT FROM AUTHOR]

Nanochitosan is known to have the potential to protect fish fillets, highly perishable products, as it can penetrate deep into the meat tissue and has high antibacterial activity. This study aimed to analyze the effect of nanochitosan incorporation to edible coating in inhibiting the degradation of Pangasius fillet quality during storage. The fillets were soaked with 2 % chitosan and nanochitosan concentrations (1 %, 2 %, and 3 %), stored for 15 days, and its quality was assessed periodically. On the 10th day of storage, the fillet coated with 2 % nanochitosan-incorporated edible coating (NEC) showed the lowest weight loss (1.41 ± 0.01 %) and maintained the pH close to neutral (6.92 ± 0.08), along with low TVB-N (33.55 mg N/100 g). and TPC (4.7 × 105 CFU/g) value, fulfilling the standard set by Indonesian National Standardization Agency. Based on the results, nanochitosan proved to extended the storage duration of Pangasius fillet while maintaining its quality. [Display omitted] • NEC extended the storage duration of Pangasius fillet until the 10th day. • Fillet with 2 % NEC showed the lowest weight loss, TPC, and TVB-N value. • NEC maintained the sensory qualities of Pangasius fillet. [ABSTRACT FROM AUTHOR]

In this study, we explored the correlation between the lysosome–mitochondrial apoptosis pathway and fish softening, as well as the correlation between ferritin degradation and lysosomal iron changes. The results indicated that ferritin levels gradually decreased, lysosomal iron first increased and then decreased and tended to stabilize, and lysosomal membrane stability significantly decreased (p < 0.05). Spearman's analysis suggested that an increase in lysosomal iron was associated with ferritin degradation. Lysosomal instability promoted the release of cathepsin D, thereby increasing the release of Bid and Bax, and inhibiting the expression of Bcl-2. Subsequently, caspase-9/−3 was activated. In addition, transmission electron microscopy revealed ultrastructural damage to mitochondria and cell nuclei, which are morphological features of apoptosis during post-mortem storage. Moreover, TUNEL staining confirmed the occurrence of apoptosis. We concluded that the lysosome– mitochondrial apoptosis pathway was active during the storage of Esox Lucius , in which ferritin degradation and increased lysosomal iron were key factors inducing lysosomal damage, and cathepsin D released by lysosomes was a key factor connecting lysosomes and mitochondria. [Display omitted] • Changes in lysosomal iron significantly correlate with ferritin levels • Changes in mitochondrial function and structure affect fillets' texture • Fish texture changes are associated with the lysosomal-mitochondrial apoptosis [ABSTRACT FROM AUTHOR]

This study aimed to investigate the effects of ultrasound-assisted curing and UV-assisted drying on the quality of semi-dried tilapia fillets through flavoromics, lipidomics, and metabolomics. Both treatments enhanced myofibril pore space and reduced moisture content (−14.84 %, P < 0.05), with ultrasound demonstrating greater effectiveness. Additionally, they also facilitated lipid oxidation (P < 0.05), which altered the flavor profile. UV treatment enhancing key aroma compounds (ROAV >1), especially octanal, 1-octen-3-one, ethyl-isovalerate, and 2-pentyl-furan, more effectively than ultrasound (P < 0.05). 420 lipid molecules and 213 metabolites were identified, including 162 differential lipids and 69 differential metabolites (VIP > 1). Correlation analysis indicated that triglycerides, fatty acids, organic acids, and nucleosides were key precursors of flavor. The sensory evaluation demonstrated that ultrasound and UV treatments synergistically enhanced fillet quality. This study introduces an innovative processing method aimed at the industrialized and efficient production of high-quality air-dried aquatic products. • Ultrasound and UV radiation improved the sensory scores of semi-dried tilapia fillets. • Ultrasound and UV radiation facilitated the formation of volatiles. • A total of 420 lipid molecules were identified, of which 162 were screened by VIP > 1. • A total of 213 metabolites were identified, of which 69 were screened by VIP > 1. • Correlation analysis showed TGs, FAs, and nucleosides were flavor precursors. [ABSTRACT FROM AUTHOR]

The effects of phenolic acid grafted-chitosan hydrocolloids (CS-g-GA/FA) on aldehyde contents from lipid oxidation in golden pompano fillets during pan-frying was investigated with an established high-performance liquid chromatography-mass spectrum method. Results indicated that pan-frying induced profound lipid oxidation and aldehydes generation with propanal, hexanal, nonanal, trans , trans -2,4-decadienal, and 4-hydroxy-2-nonenal as the abundant species. CS-g-FA and CS-g-GA effectively decreased their contents by 23.74–27.42 %, 61.69–67.42 %, 41.83–53.91 %, 29.91–48.79 %, and 61.57–65.39 % after 3 min. Most aldehyde contents decreased with the extension of pan-frying time due to the volatilization and reaction. In terms of substrate depletion, CS-g-phenolic acids effectively inhibited unsaturated fatty acids oxidation due to their decent antioxidant activity than CS. The significant lower retention rates of aldehydes in the CS-g-phenolic acids groups compared with control in chemical mode confirmed the carbonyl ammonia condensation. These results suggested that CS-g-phenolic acids serve as novel coating to reduce hazardous compounds during aquatic products thermal processing. [Display omitted] • Chitosan-g-phenolic acids exerted better inhibitory effect on aldehydes contents than CS • Pan-frying caused time-dependent depletion of polyunsaturated fatty acids of fish fillets • Chitosan-g-phenolic acids effectively hinder fish fillets lipid oxidative degradation • Chitosan-g-phenolic acids could react with the aldehydes to reduce their contents. [ABSTRACT FROM AUTHOR]

The study constructed a model of temperature fluctuation (TF, −20 °C ∼ -10 °C) during frozen status to build a link between the tilapia fillets muscle of ice crystal morphology, moisture distribution, protein oxidation index and the edible quality. When TF treatment more than 3 times, the brightness, color and hardness of frozen tilapia fillets decreased significantly, and the cooking loss and thawing loss increased significantly. The free and unconjugated water in frozen fish fillets exceeded 97 % and did not change much after 9 times TF. The K and TVB-N values were within the safety standards (K < 60 %, TVB- N < 30 mg N/100 g). The ice crystals in the tissues were significantly increased. Protein carbonyls and Ca2+-ATPase were significantly reduced, and secondary structures were irregular. Network correlation analysis showed that ice crystal morphology was significantly correlated with the color, texture and protein oxidation index of frozen tilapia fillets. The results would provide theoretical approach for the transportation and sales of tilapia industrial enterprises. • Tilapia fillets treated with cyclic fluctuation from −20 °C to −10 °C for 9 times are still edible. • The quality of fish fillets decreased significantly after 3 times treatments. • Enlargement of ice crystals is the main cause of protein oxidation. [ABSTRACT FROM AUTHOR]

This study aimed to develop a double-layer film composed of an intelligent, gelatin-based film integrated with active polyvinyl alcohol electrospun nanofibers (PVANFs). Eggplant skin extract (ESE), a colorimetric indicator, was incorporated into the gelatin-based film at varying concentrations ranging from 0 % to 8 % w /w. The gelatin film containing 8 % ESE was identified as the optimal formulation based on its superior color indication, water barrier, and mechanical properties. Savory essential oil (SEO)-loaded PVANFs were electrospun onto the optimized gelatin film to fabricate the double-layer film. Analysis of the chemical and crystalline structures and the double-layer film's thermal properties confirmed the gelatin film's physical integration with PVANFs. Morphological examination revealed a smooth surface on the film and a uniform fibrillar structure within the PVANFs. Furthermore, the developed double-layer film effectively detected spoilage in trout fish while controlling pH, oxidation, and microbial changes during storage. • A double-layer film consisting of PVA nanofibers and gelatin film was produced. • The double-layer film showed acceptable mechanical properties. • The electrospinning of PVA on gelatin film did not change morphology of nanofibers. • The double-layer film was successful in the detection of trout fish spoilage. • The double layer film controlled the spoilage of fish samples during storage time. [ABSTRACT FROM AUTHOR]

Soy isolate protein / chitooligosaccharide (SPI/COS) glycosylated conjugates was prepared and employed as an emulsifier to stabilize carvacrol-loaded nanoemulsions (CNE-SPI/COS). The effects of CNE-SPI/COS on the oxidation and aggregation of myofibrillar protein (MPs) from sea bass (Lateolabrax maculatus) were investigated. Samples were immersed in sterile water (CK), SPI/COS solution and CNE-SPI/COS solution, respectively, follow by a 15-day refrigerated storage. MPs were extracted from fish fillets at 3-day intervals, then assessed for the oxidation degree and conformational changes in MPs, as well as structural variations in myofibrils. Compared with the CK group, the results obtained from protein oxidation assessment clarified that the oxidation and aggregation of MPs was significantly reduced by the CNE-SPI/COS treatment, as evidenced by the higher total sulfhydryl content and Ca2+-ATPase activity and lower surface hydrophobicity. Conformational analysis of MPs showed that CNE-SPI/COS was effective in maintaining the ordered secondary structure of MPs and reducing the exposure of hydrophobic residues in the hydrophobic core of the tertiary structure. In addition, CNE-SPI/COS was found to be effective in protecting the microstructure of muscle fibers and myofibrils in fish fillets. These results suggest that CNE-SPI/COS can be a promising method to prevent protein oxidation and aggregation in fish. • Nanoemulsion stabilized by glycosylation product (CNE-SPI/COS) was prepared. • CNE-SPI/COS inhibited the oxidation and conformational variations of MPs. • CNE-SPI/COS maintained the microstructure of myofibrils. • Oxidation of MPs is strongly correlated with lipid oxidation. [ABSTRACT FROM AUTHOR]

Although more sustainable, feeding fish solely plant protein (PP) deteriorates their fillet quality more than animal counterparts, which additives can alleviate. This study investigated the effects of supplementing high PP diets with two additive mixtures on the fillet quality of rainbow trout (Oncorhynchus mykiss). Fish (∼2.2 g) were fed with four isonitrogenous (42 % CP) and isolipidic (20 % lipid) diets: fishmeal-based (FM), plant-based (PP), PP + A1 (PP with a mixture of krill meal, taurine, and organic selenium) and PP + A2 (PP with a mixture of proline, hydroxyproline, and vitamin C) diets, for seven months. Different diets significantly (p < 0.05) affected fatty acid composition, textural profile, hydroxyproline and collagen content, and genes related to collagen synthesis. The short-term (ice vs. -20 °C) and long-term (-20 °C, 90 days) storage conditions showed significant (p < 0.05) effects on different fillet quality attributes, including protein secondary structures. Overall, supplementing additive mixtures improved the fresh and stored fillet quality. • Additive mixtures ameliorated the negative impact of plant protein on fillet quality. • Supplementing additive mixtures in PP retain fatty acid composition close to FM diet. • The pH and liquid loss were influenced by storage conditions but not diets. • The lower aggregated β-sheet in the PP + A2 diet may help mitigate protein aggregation. • Additive mixtures upregulated p4hα(I) and col1a1, linked to higher collagen content. [ABSTRACT FROM AUTHOR]

The aging population is stimulating increased demand for dysphagia-oriented foods, yet most current options are made of ultra-processed macronutrients and lack high-quality protein and ω-3 fatty acids. This study explores the use of whole salmon fillets as a myofibrillar protein source to stabilize salmon backbone oil, creating ω-3-rich emulsion gels (50–60 vol%) for dysphasia individuals. Two-step high-pressure homogenization (HPH; 50 MPa) improved emulsion texture, storage stability, and swallowability (IDDSI level 4) by reducing oil droplet size (from 20 to 2 μm) and increasing elastic modulus by 6–8 times and viscosity by more than 10 times. These emulsion gels, rich in PUFAs, support cardiovascular health. HPH altered the structure of salmon myofibrillar proteins, transforming from micro-sized filament (2.5 μm) to assembled nano-sized micelle aggregate (400 nm) through reducing α-helix structure, crystallization, particle size, and aggregation. The protein interfacial stiffness and stability were improved, thus exhibiting greater oil droplet stabilization. The study offers a compelling reference for applying HPH in producing dysphagia-oriented products. [Display omitted] • Dysphagia-oriented salmon emulsion gels with IDDSI level 4 were prepared. • Salmon emulsion gel is high in ω-3 oil (60 vol% of oil) and rich in protein (2 w / v %). • High-pressure homogenization (HPH) improved stability and swallowing viscoelasticity. • HPH transformed macro-sized myofibrillar protein filament into nano-sized micelles. • HPH reduced the interfacial tension of myofibrillar protein by 30 %. [ABSTRACT FROM AUTHOR]

• Optimization bio-active essential oil combinations were selected. • Nano-emulsion with strong anti-bacterial activity was optimized. • Nano-emulsion prolonged the shelf life of grass crap fillets. This study aimed to develop a satisfactory essential oil (EO) nano-emulsion through high pressure microjet technology and explore its physiochemical properties and synergistic coating effects on grass carp fillets. The optimal conditions for oregano/litsea cubeba (6:4, wt%/wt%) nano-emulsion were shown to be 80 s high pressure microjet pretreatment time, 9000 lb per square inch pretreatment pressure, 6 % oil phase, and 3:2 Km (mass ratio of surfactant to co-surfactant). The obtained nano-emulsion exhibited 100.42 ± 0.96 nm oil diameter at 4 °C after 15-day storage, coupled with high stability after centrifugation, freeze–thaw and heating treatment. Compared with untreated samples at day 6 storage, the nano-emulsion-treated grass carp fillets exhibited improved textural properties, higher water-holding capacity (74.23 % ± 0.80 %), lower total volatile basic nitrogen (TVB-N, 13.46 ± 0.30 mg/100g)/thiobaric acid (TBA,0.43 ± 0.02 mgMDA/100g), and lower total viable spoilage bacteria count (4.98 ± 0.21 lgCFU/g). This study facilitates understanding the combined EOs nano-emulsion on improving the shelf life of grass carp fillets. [ABSTRACT FROM AUTHOR]

This work aimed to synthesize oregano essential oil/β-cyclodextrin microcapsules (OEO/β-CDs) and then prepare gelatin-based controlled-release antibacterial films with different OEO/β-CDs contents (0%–2%) for chilling preservation of grass carp fillets. The results of FTIR, XRD, DSC and accelerated release ratio showed that OEO was successfully encapsulated in OEO/β-CDs and its thermal stability was effectively improved. Moreover, at 2% of addition amount of OEO/β-CDs, the tensile strength of the films increased from 14.43 MPa to 18.72 MPa. In addition, the films showed significant antibacterial activity against Pseudomonas (61.52%), Aeromonas (62.87%), and Shewanella putrefaciens (66.67%). Preservation experiments showed that the films effectively prevented the increase of TVB-N, and TBA value of the refrigerated fillets and significantly suppressed the growth of spoilage organisms, thus extending the shelf life by 2–3 days. Therefore, the synthesized film has promising potential as an active packaging material for the preservation of grass carp. Synthesis of OEO/β-CDs and preparation of gelatin-based controlled-release antibacterial films for the preservation of grass carp fillets [Display omitted] • OEO/β-CDs were synthesized using co-precipitation method. • Gelatin-based composite films were prepared by incorporating OEO/β-CDs. • The film had good refrigerated preservation effect for grass carp fillets. [ABSTRACT FROM AUTHOR]

The protective mode of PostbioYDFF-3 (referred to as postbiotics) on the quality stability of refrigerated fillets was explored from the aspects of endogenous enzyme activity and the abundance of spoilage microorganisms. Compared to the control group, the samples soaked in postbiotics showed significant reductions in TVC, TVB-N and TBARS values by 39.6%, 58.6% and 25.5% on day 5, respectively. In addition, the color changes, biogenic amine accumulation and texture softening of the fish fillets soaked in postbiotics were effectively suppressed. Furthermore, the activity of endogenous enzyme activities was detected. The calpain activities were significantly inhibited (p < 0.05) after soaking in postbiotics, which declined by 23%. Meanwhile, high throughput sequencing analysis further indicated that the growth of spoilage microorganism such as Acinetobacter and Pseudomonas were suppressed. Overall, the PostbioYDFF-3 was suitable for preserving fish meat. • The quality of grass carp fillet was maintained using PostbioYDFF-3. • The inhibitory of PostbioYDFF-3 on Acinetobacter and Pseudomonas was confirmed. • The activity of calpain was reduced by PostbioYDFF-3. [ABSTRACT FROM AUTHOR]

In the current study, the preservation effect of plasma-activated water (PAW), coconut exocarp flavonoids (CF) and their combination on golden pompano fillets during refrigerated storage was investigated with emphasize on the treating sequence. PAW effectively inactivated spoilage bacteria and inhibited total volatile basic nitrogen (TVB-N) increase, while boosted the TBARS and carbonyl values. PAW+CF exerted synergistic effect on extending the period before total bacterial count and TVB-N content reaching acceptance limit than PAW or CF alone (P < 0.05). In addition, their combined treatment effectively reduced fillets discoloration and texture deterioration. Simultaneously, lipid and protein oxidation were significantly inhibited, which was comparable to CF. It was indicated that the treatment sequence of PAW and CF profoundly impact the preservation effect. Specifically, prior CF marinating followed by PAW was more effective than the opposite sequence. Thus, combination of CF followed by PAW served as promising technique for fish fillets preservation. [Display omitted] • Coconut exocarp flavonoids (CF) combined with plasma activated water (PAW) on golden pompano preservation was investigated. • PAW exerted antibacterial effect while triggered lipid and protein oxidation. • CF combined with PAW significantly enhanced preservation on golden pompano and extended its shelf-life. • CF marinating followed by PAW was more effective than the opposite sequence. [ABSTRACT FROM AUTHOR]

[Display omitted] • Photodynamic inactivation-mediated film (PLA/ALA) killed bacteria on salmon. • The PLA/ALA film protected the muscle proteins from degradation in salmon. • Four main types of protein oxidations in salmon were inhibited by the novel film. • The flavor and essential amino acids in salmon were preserved by the novel film. • The PDI-mediated film can greatly preserve the storage quality of salmon. The preservation effects of a photodynamic inactivation (PDI)-mediated polylactic acid/5-aminolevulinic acid (PLA/ALA) film on the storage quality of salmon fillets were investigated. Results showed that the PDI-mediated PLA/ALA film could continuously generate reactive oxygen species by consuming oxygen to inactivate native pathogens and spoilage bacteria on salmon fillets. Meanwhile, the film maintained the content of muscle proteins and their secondary and tertiary structures, as well as the integrity of myosin by keeping the activity of Ca2+-ATPase, all of which protected the muscle proteins from degradation. Furthermore, the film retained the activity of total superoxide dismutase (T -SOD), suppressed the accumulation of lipid peroxides (e.g., MDA), which greatly inhibited four main types of protein oxidations. As a result, the content of flavor amino acids and essential amino acids in salmon fillets was preserved. Therefore, the PDI-mediated antimicrobial packaging film greatly preserves the storage quality of aquatic products by preserving the protein quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • Magnetic nanoparticles (MNPs) assist ed freezing-thawing (NNMT) was studied. • NNMT treament showed the compact and ordered fibrous structure. • NNMT inhibited the conformational change of myofibrillar protein. • NNMT could better stabilize the structural proteins. This study investigated the impact of magnetic nanoparticles (MNPs) -assisted cryogenic freezing integrated with MNPs combined microwave thawing (NNMT) on the structural integrity of myofibrillar proteins and alterations in protein profiles in salmon fillets. The NNMT showed the lowest myofibrillar fragmentation index (MFI) value (2.73 ± 0.31) among the four freezing-thawing groups. The myofibrillar structure exhibited the highest level of integrity, while the myofibrillar proteins demonstrated minimal aggregation and displayed the most stable secondary and tertiary structures in response to NNMT treatment. Compared with the other three treatments, NNMT exhibited a high abundance of ionic and hydrogen bonds, resulting in stronger interactions between the proteins and water molecules. The label-free proteomics analysis revealed that different freezing-thawing methods primarily affected the cytoskeletal proteins, with collagen and myosin being down-regulated due to degradation caused by cold stress and recrystallization. Additionally, NNMT demonstrated a superior capability in stabilizing salmon cytoskeletal proteins. [ABSTRACT FROM AUTHOR]

• Multifunctional preservation pad has good preservation properties. • The liposome embedding essential oil has good physicochemical and sustained release properties. • The preservation properties of the pads come from water absorption, anti-reverse osmosis and essential oil liposomes. • The synergistic bactericidal effect of essential oil liposomes enhanced the preservation property. The juice exudation of aquatic products oozes out during storage can influence storage quality. Herein, a novel basil essential oil liposome unidirectional water-conducting sustained-release preservation pads (BEOL/UCSP) were prepared with nylon mesh as water-conducting layer, basil essential oil liposome (BEOL) as sustained-release preservation layer, and diatomite and absorbent-cotton as water-absorbing layer. EL/UCSP, β-CL/UCSP, and BEO/UCSP were prepared after BEOL was replaced by eugenol liposome, β-caryophyllene liposome, and BEO. BEOL are microspheres with bilayer structure, had good storage stability, centrifugal stability, thermal stability, embedding capacity, sustained-release, and oxidation resistance, and the main components of preservatives had a synergistic effect on antibacterial properties. The pads without preservative can initially slow down quality deterioration. BEOL/UCSP can directionally absorb exudate and realize long-term sustained-release of preservative, has excellent antibacterial and antioxidant effect, and extended shelf life of Lateolabrax japonicus fillets from 6.0 days to 12.8 days. The BEOL/UCSP can provide technical theoretical support for preservation materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • The mitigating effect of legume seed marinades was higher in the PhIP model compared to MeIQx. • A dose-dependent relationship was found between marinade levels and HAs inhibition in fish fillets. • All marinades were effective in reducing TBARS and carbonyl and retaining thiol content. • A strong correlation was found between TBARS and carbonyl and the level of HAs. The present study aimed to investigate the potential of marination with extracts prepared from five legume seeds on heterocyclic amine (HA) formation in chemical models and air-fried fish fillets. In terms of total HAs, clove seed marinade (CSM) was found with the maximum inhibitory effect (43.98 %), followed by tamarind seed marinade (TSM) (40.26 %), fenugreek seed marinade (FSM) (39.07 %), acacia seed marinade (ASM) (37.99 %), and black bean seed marinade (BSM) (29.95 %). In particular, at higher levels (3 mg/mL, 4 mg/mL), CSM and FSM achieved the greatest mitigating effect against 4,8-DiMeIQx, 7,8-DiMeIQx, and MeIQx. Furthermore, all marinades were effective in lowering thiobarbituric acid-reactive substances (TBARS) and carbonyl and retaining thiol content relative to the control. PCA analysis revealed that higher levels of ASM, BSM, and FSM had better mitigating effect against IQ and MeIQx formation, whereas Pearson correlation shows that TBARS and carbonyl were positively correlated to HAs. [ABSTRACT FROM AUTHOR]

• Stunning stress resulted in textural softening and poor water retention of fillets. • Stunning stress led to myofibril fragmentation and detachment from sarcolemma. • Stunning stress facilitated cathepsin B and L releases in myofibrils. • Myofibril segmentation and increased cathepsin contributed to fillet softening. This study aimed to investigate the effect of stunning stress on textural properties and water-holding capacity (WHC) of silver carp (Hypophthalmichthys molitrix) fillets and its underlying mechanisms based on intrinsic proteases activity, myofibril microstructure, and myowater dynamic measurements. The results suggested that compared with the non-stressful percussion, ice/water and gill cut stunning resulted in accelerated muscle tenderization with intensive myofibril disintegration and sarcolemma-myofibril detachments. Myowater mobility and distribution were altered by stunning stress, in which gill cut facilitated the migration of immobilized water and free water, thus enhancing the centrifugation loss. In addition, stunning stress promoted the activation of endogenous proteases and the release of cathepsin B and L from lysosomes to myofibrils, which showed significant (P < 0.01) correlations with decreased shear force and elevated myofibril fragmentation index of fillets. Therefore, faster accumulation of cathepsins and myofibril disintegration together contributed to the weakening of texture and WHC in stunning-stressed fish fillets. [ABSTRACT FROM AUTHOR]

Highlights • Dietary oils affect positional distribution of fatty acids in glycerolipids in fish. • Dietary 16:0 and 18:1n-9 are easily utilized for energy supply in Nile tilapia. • Tilapia specifically accumulates high 18:2n-6 and low 18:3n-3 in phospholipids. • Fish oil intake raises deposition of EPA + DHA at sn-1/3 in triglyceride in tilapia. • Nutritional value of fish fillets could be regulated by changing dietary oils. Abstract The nutritional value of fish fillet can be largely affected by dietary oils. However, little is known about how dietary oils modify lipid molecules in fish fillets. Through biochemical and lipidomics assays, this study demonstrated the molecular characteristics of fillet lipids in Nile tilapia fed with different oils for six weeks. High 18:2n-6 and low 18:3n-3 deposition in phosphoglycerides resulted high 18:2n-6/18:3n-3 ratio in tilapia. Dietary n-3 VLCUFAs intake increased its deposition at sn-1/3 of triglycerides and at sn-2 of phosphatidylcholines. Irrespective of dietary oil, 16:0 was distributed preferentially at the outer positions of glycerol backbone. High 18:2n-6 accumulated at sn-2 position for fish fed with n-3 PUFA-enriched oils. High 18:3n-3 deposited at sn-1/3 in TG, sn-1 in phosphatidylethanolamines, while at sn-2 in phosphatidylcholines. Together, dietary oils change the composition and positional distribution of fatty acids on the glycerol backbone, and change nutritional value of fish for human health. [ABSTRACT FROM AUTHOR]

[Display omitted] • The magnetic fields assisted freezing could change the quality of catfish meat. • The magnetic field shortened the phase transition time of fillet freezing. • The SMF and AMF with different intensity had distinct effects on protein structure. • The content of hydrogen bonds and secondary structure proportion were altered. • The solubility and stability of protein were improved by magnetic field treatment. The effect of static and alternating magnetic fields assisted freezing with intensity of 1, 2, and 3 mT on the microstructure and protein properties of channel catfish fillet were investigated. The results showed that the magnetic field treatment shortened the phase transition time of freezing, and significantly reduced the size of the formed ice crystals. The changes of trichloroacetic acid-soluble peptide, Ca2+-ATPase activity, particle size, and Zeta potential, which represented solubility, denaturation and aggregation of protein, indicated that magnetic field treatment could improve the protein stability. The chemical force analysis, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), and Fourier transform infrared spectroscopy (FTIR) results proved that the magnetic field could change the structure of protein. Furthermore, these changes had effects on the thermal stability of catfish meat protein which reflected by increasing of the transition temperature and enthalpy. However, the waveform and intensity of magnetic field affected the stability of protein structure. [ABSTRACT FROM AUTHOR]

• UHP treatment changed the quality and protein characteristics of fillets. • MF storage reduced the flora activity and water holding capacity of fillets. • UHP-MF delayed protein denaturation by inhibiting protein and lipid oxidation. • UHP-MF delayed quality deterioration by inhibiting flora activity and diversity. • UHP 300 -MF effectively extended the shelf life of fillets by at least 10 days. Ultra-high pressure (UHP) and magnetic field (MF) are emerging food preservation technologies, but the research on the effects of combined treatment (UHP-MF) on aquatic products quality is insufficient. Hence, we explored the effects of UHP-MF treatment on the protein properties, microbial action and quality characteristics of stored grass carp fillets. Results showed that 300 MPa UHP treatment combined with MF storage (UHP 300 -MF) delayed the protein oxidation of stored fillets by inhibiting the accumulation of protein radical and the formation of lipid pro-oxidation products, thus the quality (texture, color) deterioration caused by oxidation was deferred. Additionally, 16S rDNA bacteria flora analysis revealed that UHP 300 -MF treatment inhibited the flora activity and diversity of fillets, delayed the protein degradation and quality deterioration caused by microbial action. Overall, UHP 300 -MF treatment suppressed the lipid and protein oxidation as well as microbial action, retarded the quality deterioration, and prolonged the shelf life of stored fillets. [ABSTRACT FROM AUTHOR]

[Display omitted] • Denaturation of proteins can occur in the thawing process without physical damage of ice. • Oxidation reactions occurred in the thawing process decreased the WHC of MPs. • Long-term frozen decreased the anti-oxidant enzyme activity in exudates but increased the content of lipid oxidation products. • Exudates is a potential tool for investigating the protein behaviors in the thawing process. Oxidation of myofibrillar proteins (MPs) is considered as an important reason for the quality deterioration of frozen stored fish fillets, but the impact of the thawing process on the oxidation and thereby property changes of MPs has been largely neglected. In this study, we incubated MPs for 24 h at 4 °C with thawing exudates collected from fish fillets stored at −20 °C for 0–5 months to mimic the thawing process. Exudates treatment induced the increased content of carbonyls, Schiff bases, and dityrosine, structural changes, and the decreased water-holding capacity of MPs. SDS-PAGE and LC-MS/MS results indicated that exudates caused the degradation of MPs with the potential involvement of lipid oxidation products, hemoglobin, and proteases. Prolonged frozen storage decreased antioxidant enzyme activity and increased lipid oxidation products in exudates, which might be the reason for exudates from fillets frozen for longer periods can cause more severe oxidation and degradation of MPs. [ABSTRACT FROM AUTHOR]

• NaCl further promotes protein degradation and oxidation during the frozen storage. • Protein degradation leads to lighter bands of tropomyosin and troponin in SDS-PAGE. • Myosin heavy chain undergoes both degradation and oxidation during the storage. • Variety of oxidative modification increases in brined fillets after frozen storage. • Amino acids in tail portion of myosin are prone to be oxidized than head portions. Protein degradation and oxidation are two major alterations during the storage of processed bighead carp fillets. This study conducted a comparative analysis of degraded and oxidized products as well as oxidation sites in fresh, frozen and brined frozen bighead carp fillets. Frozen storage played a dominant role in protein degradation and oxidation, and brining promoted these changes. In brined frozen samples, the decreased SDS-PAGE band intensities for tropomyosin, troponin, and myosin light chain were mainly due to their degradation. Myosin heavy chain fast skeletal muscle was the most oxidized and degraded protein during storage, with modifications such as monooxidation, protein-lipid peroxidation adducts, and α-aminoadipic semialdehydes formation. Amino acids in the tail portion of myosin were prone to oxidation than the head portions. Our results provided comprehensive insights into protein degradation and oxidation in bighead carp during storage, helping to assess the specific fate of oxidative products in future dietary investigations. [ABSTRACT FROM AUTHOR]

• Multi-layer films were developed on the basis of furcellaran. • The added film additives are an element of activities aimed at improving quality and gave the films active properties. • Storing fish in the created films demonstrated better microbiological parameters. To improve the quality of multi-layer film, four-layer films based on furcellaran and active ingredients: gelatin hydrolysate, curcumin, capsaicin, montmorillonite and AgNPs, were produced in an innovative manner. The films were characterised by SEM and AFM analysis. Along with an increase in the concentration of active ingredients, the structure of the film becomes less homogeneous, which may affect the functional properties. The objective of the study was to analyse changes in the functional properties of the newly-obtained films and to verify their potential as packaging materials for fish products. With the increase in active ingredient concentration, water properties also improved, but there were no noticeable significant effects on mechanical properties. For antioxidant properties, the obtained values were within 1.04–2.74 mM Trolox/mg (FRAP) and 7.67–40.49% (DPPH). The obtained multi-layer films were examined with regard to the shelf-life of salmon. For this purpose, salmon fillets were packed in films having good antioxidant and functional properties. The films were effective in microorganism growth inhibition responsible for fillet spoilage during storage. The microorganism number in the active film-stored samples was lower by 0.13 log CFU/g on day 12 versus the control. However, film application did not retard lipid oxidation in the salmon fillets. Nonetheless, the films show great potential as active packaging materials, extending the shelf-life of the packed foods. [ABSTRACT FROM AUTHOR]

• Protein digestibility decreased in brined fillets after 6 months of frozen storage. • Nutritional attributes decreased with the increase in protein oxidation levels. • Degradation of peptide at the site adjacent to modified amino acids was inhibited. • Malondialdehyde adduct was responsible for inhibited protein intestinal transport. This study examined the effects of protein oxidation on digestion behavior. The oxidation levels and in vitro digestibility of myofibrillar proteins from fresh-brined and frozen bighead carp fillets were investigated, and the intestinal transport property was characterized by comparing the peptides on both sides of the intestinal membrane. Frozen fillets showed high oxidation levels, low amino acid content and in vitro protein digestibility, which were further increased by brining. After storage, the number of modified peptides from myosin heavy chain (MHC) increased over 10-fold in NaCl-treated samples (2.0 M). Various types of side-chain modifications in amino acids were identified, such as di-oxidation, α-aminoadipic semialdehyde (AAS), γ-glutamic semialdehyde (GGS), and protein-malondialdehyde (MDA) adducts, mainly originating from MHC. The Lysine/Arginine-MDA adducts, AAS, and GGS decreased protein digestibility and their intestinal transportation. These findings suggest that oxidation impacts protein digestion and should be considered in food processing and preservation strategies. [ABSTRACT FROM AUTHOR]

Highlights • Doehlert design and desirability function allow optimize fish samples dissolution. • Ultrasound energy was used to increase the efficiency of the TMAH dissolution. • The method presents good analytical characteristics allowing simultaneous treatment. • Calcium, Mg, Fe and Zn were determinate from fillet fish samples using FAAS. Abstract Doehlert design and desirability function were used in the optimization of an ultrasound assisted dissolution method of fish fillet samples with tetramethyl ammonium hydroxide (TMAH) for the determination of Ca, Fe, Zn and Mg by flame atomic absorption spectrometry. The variables values after optimization were 620 μL (volume of TMAH), 25 min (sonication time) and 46 °C (bath temperature). The quantification limits for Ca, Mg, Fe and Zn were 56, 107, 23 and 2.9 μg g−1, respectively. Accuracy was evaluated by comparing the results generated from the analysis of the samples treated by the proposed method and by wet digestion. Additionally, accuracy for Fe and Zn was assessed by the analysis of certified reference materials Tort-3 (Lobster hepatopancreas), ERM-CE 278 (mussel tissue) and Dolt-4 (Fish liver). There were no significant differences between the results obtained at a 95% confidence level when results were evaluated by t -test application. [ABSTRACT FROM AUTHOR]

Highlights • A multispectral model was built for DHA and EPA prediction. • A novel PN-GA algorithm was used to select the key variables. • MLR models showed better results for DHA and EPA in two fish fillets. • The dynamic changes of DHA and EPA were visualized. Abstract A multispectral model for the detection of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) changes in grass carp and salmon fillet was developed using physarum network and genetic algorithm (PN-GA) method for the first time. Partial least-squares regression (PLSR), multiple linear regressions (MLR), and principal component regression (PCR) algorithms were used to predict the DHA and EPA using optimal wavelengths selected by PN-GA. The MLR models showed the best DHA prediction results for both grass carp and salmon fillets, and also showed good prediction for EPA in grass carp fillet but poor prediction in salmon fillet. The MLR models were then applied for visualizing the spatial distribution of DHA and EPA changes in two fish fillets. The current results demonstrated that a developed multispectral imaging system could be feasibly constructed for DHA and EPA measurement in fish species with the optimal wavelengths selected by PN-GA method. [ABSTRACT FROM AUTHOR]

Multielement isotope ratio was assessed in fat and defatted (protein) fillet of 130 rainbow trout, reared with feed incorporating a high or low fish content in 20 Italian farms, focusing on two northern Italian regions (Friuli Venezia Giulia and Trentino). The aim was to investigate the ability of isotopic analysis to trace the geographical origin of trout, also according to the type of feed. The carbon, nitrogen and sulphur isotope ratios of feed and fillet were highly positively correlated both within each matrix (feed or fillet) and between the two matrices and negatively correlated with the δ 2 H and δ 18 O of feed and the δ 2 H fat . The δ 2 H protein and δ 18 O protein were positively interrelated with the δ 18 O of tank water. By applying the tested Partial Least Squares – Discriminant Analysis multiclass model (85 fillets) to the validation dataset (45 fillets), 91% accuracy was obtained for the two Italian regions. [ABSTRACT FROM AUTHOR]

In order to evaluate the effects of magnetic nanoparticles plus microwave (MNPMT) or far-infrared (MNPFT) thawing on protein conformation changes and moisture migration of red seabream ( Pagrus major ) fillets, cold storage thawing, microwave thawing, MNPMT, far-infrared thawing and MNPFT were subjected to red seabream fillets. DSC and dynamic rheology were conducted to analyze physicochemical changes. Raman spectra before and after isotope H/D exchange, intrinsic fluorescence and UV second derivative spectra were carried out to explore myofibrillar protein structural changes. Low-field NMR was used to test water migration. SEM was performed to observe fiber microstructure. Results indicated that MNPMT and MNPFT both had a desirable thermal stability and gelation property. Besides, both showed stable protein secondary and tertiary structure. Immobilized water in them also had no significant changes compared with fresh sample. This research provided some novel thawing technologies for application in food industry. [ABSTRACT FROM AUTHOR]

A quantitative method for analysis of amphenicols (chloramphenicol – CAP, thiamphenicol – TAP and florfenicol – FF) in Nile tilapia using LC–MS/MS is described. A simple sample preparation procedure was optimized using a Plackett-Burman design. The method was validated in accordance with Decision 2002/657/EC. Repeatability and reproducibility were less than 10.7% and 16%, respectively, for all compounds. Recoveries varied from 79.8% to 92.0%. CCα was 0.019, 54.81 and 54.93 μg.kg −1 for CAP, FF and TAP, respectively. CCβ was 0.068, 64.88 and 58.91 μg.kg −1 for CAP, FF and TAP, respectively. Limits of quantification (LOQ) were 12.5 μg.kg −1 for FF and TAP and 0.15 μg.kg −1 for CAP. Nile tilapia fillets (n = 32) analyzed did not contain chloramphenicol. Thiamphenicol was detected in one sample (3.1%) and florfenicol was detected in every sample, all of them at concentrations below the maximum residue limit. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effects of different stunning methods (percussion, T1; immersion in ice/water slurry, T2; gill cut, T3) on antioxidant status, in vivo myofibrillar protein (MP) oxidation, and the susceptibility to postmortem oxidation (induced by hydroxyl radical oxidizing system) of silver carp ( Hypophthalmichthys molitrix ) fillets. Stress conditions, antioxidant enzyme activities, and protein oxidation parameters were analyzed during 72 h postmortem. The results indicated that the strongest stress conditions in the T3 group led to impaired glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD) activity, and significantly ( P  < .05) higher carbonyl concentrations, thereby promoted in vivo MP oxidation of fillets. The T3 group also showed severe losses in myosin heavy chain (MHC) intensities and sulfhydryl groups at higher H 2 O 2 concentrations. Overall, fillets from the T3 group were more susceptible to oxidative damage, and the T1 and T2 groups maintained better quality in terms of lower MP oxidation rates. [ABSTRACT FROM AUTHOR]

This study evaluates the reliability of a handheld NIR device in distinguishing fillets and patties of Atlantic cod (n = 80) from those of haddock (n = 90), in comparison with a FT-NIR benchtop spectrometer. The authentication issue was faced by Linear Discriminant Analysis (LDA) and Soft Independent Modelling of Class Analogy (SIMCA), pre-treating spectral data with different algorithms, and validating models both internally and externally. The best LDA models gave 100% correct classification in prediction. Sensitivity >65% and specificity >74% in prediction were calculated for the best SIMCA models. No significant differences ( P  > .05) were found between the two instruments by McNemar test. Thus, the work demonstrated that a handheld NIR device can be a simple, cost-effective, and reliable alternative to benchtop spectrometers in fish fillet and patty authentication. These important findings can help in improving commercial fraud fight, extending the possibility to authenticate fish species also in processed products. [ABSTRACT FROM AUTHOR]

This study investigated the effects of chitosan-based coatings on flavor retention of refrigerated grass carp fillets by using various indicators: free amino acids (FAA), nucleotides, trimethylamine (TMA), volatile profile, sensory quality, and electronic nose analysis. The results indicated that chitosan-based coatings contributed to the significant reduction of off-flavor compounds, such as TMA, hypoxanthine (Hx) and histidine, and accumulation of inosine monophosphate (IMP) and umami-associated FAA. GC–MS analysis showed 23 volatile organic compounds, including many C 5 –C 9 aldehydes and alcohols in the fresh fillets. The coating treatments, especially chitosan-clove bud essential oil composite coatings, sharply reduced the relative content of off-odor volatiles, such as hexanal, octanal and 1-octen-3-ol. According to the results of the sensory evaluation and electronic nose analyses, chitosan coating combined with glycerol monolaurate and clove bud essential oil was a promising method to improve the edibility of grass carp fillets by maintaining flavor quality during refrigerated storage. [ABSTRACT FROM AUTHOR]

Channel catfish skin is a by-product from catfish fillet production. Collagens were extracted from catfish skins by: (1) acid; (2) homogenization-aided; and (3) pepsin-aided extraction methods. Kinetic analysis of extraction was performed. SDS-PAGE was carried out for all collagens extracted under different conditions. Protein solubility, zeta potential, circular dichroism and gel strength of the collagen extracted by three methods were studied to determine optimal extraction conditions. Protein recovery rate from minced skins extracted with pH 2.4 HCl containing 23.6 KU/g pepsin was the highest (64.19%). SDS-PAGE showed that collagens extracted with different methods had different proteins ratio patterns, even though the molecular mass of collagen subunits were similar, 123 and 113 KDa for α 1 and α 2 chains, 226 KDa for β chain and 338.5 KDa for γ chain, respectively. Channel catfish skin collagens were typical type I collagens and could have applications in food, medical and cosmetic industries. [ABSTRACT FROM AUTHOR]

[Display omitted] • The changes of volatile compounds in refrigerated tilapia were identified. • KEGG compounds and metabolic pathways were classified via metabolomics. • Key metabolic pathways and differential metabolites were revealed. • Potential metabolic network map related to odor deterioration was explored. Odor deterioration of tilapia during cold storage is unavoidable and affects flavor and quality severely. Odor is characterized by the abundance of volatile compounds and metabolites. In this study, headspace-solid phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC–MS) and metabolomic analysis were applied to explore the volatile compounds, differential metabolites, and metabolic pathways related to the odor deterioration of tilapia during cold storage. A total of 29 volatile compounds were detected to be associated with the odor deterioration of tilapia. And 485 differential metabolites were screened, of which 386 differential expressions were up-regulated and 99 differential expressions were down-regulated. Three major metabolic pathways including linoleic acid metabolism, alanine, aspartate, glutamate metabolism, and nucleotide metabolism were obtained. A potential metabolic network map was also proposed. This study contributes to revealing the metabolic mechanisms of odor deterioration in tilapia during cold storage and providing a theoretical reference for the regulation of flavor and quality. [ABSTRACT FROM AUTHOR]

• Bilayer active film inhibited texture softening of refrigerated fillets. • Lower levels of endogenous enzyme activities were shown in packaged fillets. • The inner layer absorbed exudates with high enzyme activity to protect the fillets. • Active film inhibited protein oxidation and degradation during chilled storage. • The exudates accelerated the texture deterioration of fillets. Herein, the protective pattern of bilayer film on the texture stability of fillets was discussed in terms of endogenous enzyme activity, as well as protein oxidation and degradation. The texture properties of fillets wrapped with nanoparticles (NPs) bilayer film were greatly improved. NPs film delayed protein oxidation by inhibiting the formation of disulfide bond and carbonyl group as evidenced by the increase of α-helix ratio (43.02%) and the decrease of random coil ratio (15.87%). The protein degradation degree of fillets treated with NPs film was lower than that of control group, specifically with a more regular protein structure. The exudates accelerated the degradation of protein, while NPs film effectively absorbed exudates to delay protein degradation. Overall, the active agents in the film were released into the fillets to play an antioxidant and antibacterial roles, and the inner layer of film could absorb exudates, thus maintaining the texture characteristics of fillets. [ABSTRACT FROM AUTHOR]

• Feeding grass carp with faba bean conferred them with "crisp" muscle texture. • "Crisp" grass carp muscle is characterized by substantial protein N -glycosylation. • N -glycosylated proteins participate in myogenesis, muscle function, & ECM formation. • N -glycosylation regulation is independent with phosphorylation regulation and protein expression. • These findings lay a foundation for optimizing fish fillet texture & quality. Post-translational protein modification affects muscle physiochemistry. To understand the roles of N- glycosylation in this process, the muscle N- glycoproteomes of crisp grass carp (CGC) and ordinary grass carp (GC) were analyzed and compared. We identified 325 N- glycosylated sites with the NxT motif, classified 177 proteins, and identified 10 upregulated and 19 downregulated differentially glycosylated proteins (DGPs). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes annotations revealed that these DGPs participate in myogenesis, extracellular matrix content formation, and muscle function. The DGPs partially accounted for the molecular mechanisms associated with the relatively smaller fiber diameter and higher collagen content observed in CGC. Though the DGPs diverged from the identified differentially phosphorylated proteins and differentially expressed proteins detected in previous study, they all shared similar metabolic and signaling pathways. Thus, they might independently alter fish muscle texture. Overall, the present study provides novel insights into the mechanisms underlying fillet quality. [ABSTRACT FROM AUTHOR]

[Display omitted] • More down-regulated phosphosites of structural proteins were found at d6 than d0. • Dephosphorylation of structural proteins was related with texture softening. • Myosin, actin, collagen and cytoskeleton were major structural dephosphoproteins. • Kinases, phosphatases and assembly regulators tended to be dephosphorylated. • Dephosphorylation mostly appeared at Serine site in structural proteins of muscle. Texture is an important sensory attribute of fish affected by modifications of structural proteins in muscle architecture. To investigate the changes in protein phosphorylation during texture softening of fish, the proteins of grass carp muscle after chilling storage of 0 day and 6 days were compared by phosphoproteomics, and their association with texture was analyzed. Totally 1026 unique phosphopeptides on 656 phosphoproteins were identified as differential. They were mainly classified as intracellular myofibril and cytoskeleton, and extracellular matrix, of which the molecular function and biological process were binding into supramolecular assembly and myofilament contraction. The concomitant dephosphorylation of kinases and assembly regulators indicated dephosphorylation and disassembly tendency of sarcomeric architecture. Correlation analysis defined the relation between texture and dephosphorylation of myosin light chain, actin, collagen and cytoskeleton. This study revealed that protein phosphorylation may affect the texture of fish muscle through regulating sarcomeric assembly of structural proteins in muscle architecture. [ABSTRACT FROM AUTHOR]

• The CML and 5-HMF formation was more affected by lipid oxidation. • The a*, b* and TBARS of fillet was extremely correlated with CML production. • Volatiles (OAV > 1) were mainly generated from lipid oxidation and Maillard reaction. • Pyrazines was only existed in pan-fried grass carp fillets. This study aimed to evaluate the evolution of quality attributes, oxidation index, glycosylated hazardous products, aroma characteristics of grass carp fillets and their relationship under air-frying, roast-frying and pan-frying. With frying progressed, the level of carbonyl protein and lipid oxidation products increased significantly (following air-frying > pan-frying > roast-frying), and the latter decreased subsequently after 6 min. Fillets possessed by frying increased significantly Nε-carboxymethyl-lysines (CML) and 5-hydroxymethylfurfural (5-HMF) levels, whose increment was pan-frying > air-frying > roast-frying. Compared to raw, eighty-seven volatiles were identified and the total concentrations of those increased gradually in air-frying, but then decreased up to 6 min in roast-frying and pan-frying. Furthermore, significant correlations between CML, TBARS and 5-HMF, quality attributes, oxidation index; volatiles (VIP and/or OAV > 1) and lipid oxidation index were obtained. Conclusively, fillets possessed by air-/roast-frying showed more lipid oxidation and alcohols/aldehydes, while pan-fried enriched CML and pyrazines. [ABSTRACT FROM AUTHOR]

Biochemical and microbial changes after harvest strongly affect the final quality and shelf life of fish and fish products. In this study, the role of microbes in the degradation of adenosine triphosphate (ATP), and the origin of adenosine monophosphate deaminase (AMPD) and acid phosphatase (ACP) in common carp fillets during different stages of chilled storage (at 4 °C) were investigated. The content of ATP, ADP, AMP, IMP, HxR, and Hx, the activity of AMPD and ACP, and the total count of viable, Aeromonas , Pseudomonas , H 2 S-producing bacteria, and lactic acid bacteria were examined. Results indicated that the population of microbial communities in control samples increased with storage time, and Pseudomonas peaked on the 10th day of storage. Changes in AMPD activity were less related to the abundance of microbes during the entire storage period. However, ACP was derived from both fish muscle and microbial secretion during the middle and late stages of storage. Degradation of ATP to IMP was not affected by spoilage bacteria, but the hydrolysis of IMP, and the transformation of HxR to Hx was affected considerably by the spoilage bacteria. [ABSTRACT FROM AUTHOR]

• Fat content differs between the NQC and whole fillet of farmed Atlantic salmon. • Dioxins and dl-PCBs do not differ between the NQC and whole fillet. • For contaminants, the NQC is a representative cut for whole fillet. • The whole salmon fillet is preferable when analysing nutrient contents. Risk- benefit assessments of seafood require high-quality food composition data. In accordance with EU regulations, Atlantic salmon (Salmo salar) has conventionally been sampled using the Norwegian Quality Cut (NQC), a sub-cut of the middle section of the fish, in Norwegian surveillance programs. By comparing the contents of nutrients and contaminants in 34 samples of farmed Atlantic salmon, we aimed to evaluate the representativeness of the NQC compared with the whole fillet. Of the 129 analytes evaluated, eight single analytes, in addition to 25 different fatty acids, showed significant differences between the cuts. Significant differences were evident for total fat, including eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and sum PCB-6, but not for the sum of dioxins and dioxin-like PCBs. We further suggest that the NQC may still be used in large-scale sampling of Atlantic salmon, and that the whole fillet would be preferable when analysing the content of nutrients. [ABSTRACT FROM AUTHOR]

• Brining increased water-holding capacity (WHC) of fillets during frozen storage. • Protein denaturation affected changes in fish quality during pre-phase of storage. • Oxidation became dominant and influenced fish quality in later stage of storage. • 0.5 M NaCl increased WHC with few quality deteriorations in frozen fillets. This study aimed to find the specific relationship between quality traits and myofibrillar proteins (MPs) alteration of salted fish during frozen storage. Protein denaturation and oxidation occurred in frozen fillets, with the denaturation occurring before oxidation. In the pre-phase of storage (0-12 weeks), protein structural changes (secondary structure and surface hydrophobicity) were closely related to the water-holding capacity (WHC) and textural properties of fillets. The MPs oxidation (sulfhydryl loss, carbonyl and Schiff base formation) were dominated and associated with changes in pH, color, WHC, and textural properties during the later stage of frozen storage (12-24 weeks). Besides, the brining at 0.5 M improved the WHC of fillets with less undesirable changes in MPs and quality traits compared to other concentrations. The 12 weeks was an advisable storage time for salted frozen fish and our results might provide an available suggestion for fish preservation in aquatic industry. [ABSTRACT FROM AUTHOR]

• Double-layer films with aqueous extract of clitoria flower (BP) were prepared. • Double-layer film showed strong antimicrobial and antioxidant activity. • BP enhanced UV-barrier of double-layer films and give them intelligent activity. • The wrapped fish showed better microbiological parameters and low lipid oxidation. Innovative, intelligent and active double-layer films, based on furcellaran and with the addition of gelatin hydrolysates, have been obtained for the first time. An aqueous extract of clitoria flower in 3 concentrations was included in the 1st FUR layer. The films demonstrated strong antimicrobial effects, but did not exhibit fungicidal properties. The antioxidant properties of the films were within the range of 2.27–3.92 mM Trolox/mg (FRAP method) and 36.67–61.24 % (DPPH method). The films were used as active packaging materials in salmon fillets, which were stored for a period of 12 days in 4 °C. Analysis concerning microbiological properties of the stored fillets showed the possibility of extending their shelf-life by 6 days. Lipid oxidation, determined by TBARS has delayed. The obtained films are a promising material for the packaging industry. This is an important aspect within the context of global food waste and also the need to reduce synthetic materials. [ABSTRACT FROM AUTHOR]

• Digestibility and modification sites of MPs by two oxidation models were studied. • Oxidation decreased amino acid content in digested myofibrillar proteins (MPs). • More types of modification were observed after frozen storage in digested MPs. • Actin was more susceptible to hydroxyl radical oxidizing system among all MPs. This study aimed to investigate the effect of hydroxyl radical oxidizing system (HROS) and endogenous oxidizing system (EOS, i.e., frozen storage at −20 °C) on protein oxidation, digestive properties, and peptide modification of myofibrillar proteins (MPs) in bighead carp (Hypophthalmichthys nobilis) fillets. The oxidation degree increased with the frozen time and H 2 O 2 concentration as evidenced by carbonyl group generation and sulfhydryl group loss in MPs. The digestibility of protein declined gradually during frozen storage, while it increased after treatment with 5 mM H 2 O 2 compared with no H 2 O 2 intervention. More modification numbers and types were observed in the EOS group than HROS in digested MPs peptides, which might be due to the complexity of the frozen fillet system such as the presence of lipid. The potential conversion of α-aminoadipic semialdehyde (AAS) to α-aminoadipic acids (AAA) was observed in HROS. Additionally, the myosin heavy chain was more susceptible to oxidation among all MPs by EOS oxidation. [ABSTRACT FROM AUTHOR]

• Trip-step IR spectroscopy could monitor the main differences in taste-related metabolites. • Temperature fluctuations during frozen storage promoted the increase of umami and sweet amino acids. • AMP and IMP were retained during the first and second temperature fluctuations. • MM-IR was an effective method to identify taste components. In this study, the effect of temperature fluctuations on the taste quality of tilapia fillets during frozen storage was investigated. Major temperature-responsive factors included free amino acids (FAAs) and flavor nucleotides in fish fillets, which were identified using multidimensional infrared spectroscopy (MM-IR). The main FAA in tilapia fillets is a sweet amino acid (glycine). Compared with the control group, the umami FAAs and sweetness FAAs were significantly increased, and the total FAAs content increased to 1.30 times after the ninth fluctuation, reaching the highest level (611.16 ± 73.60 mg/100 g). Considering the equivalent umami intensity values, adenosine monophosphate and inosine monophosphate were retained during the first and second temperature fluctuations. In addition, the content of Na+, K+, and Ca2+ decreased (P < 0.05). Therefore, MM-IR is an effective method to identify taste components. With regard to taste quality, temperature fluctuations in the twofold range have an umami-enhancing effect. [ABSTRACT FROM AUTHOR]

• Light salting improves water-holding capacity of tilapia during freezing-thawing. • Presalting decelerates softening of tilapia fillet during repeated freezing-thawing. • Myofibril disassembly and reorganization contribute to quality improvement. • Titin is better preserved in lightly salted fillets during repeated freezing-thawing. The present study evaluated the effects and underlying mechanisms of light salting on quality properties of tilapia fillets during repeated freezing-thawing. Light salting was found to improve water-holding capacity and decelerated texture softening in tilapia fillets during repeated freezing-thawing. Instead of tissue distortion and heterogeneous aggregates in control groups, light salting promoted myofibril disassembly and formation of an ordered protein network with the solubilized myofibrillar proteins. The myofibrils presented an overall amorphous appearance with the loss of M-lines, removing the restraints to myofibril swelling and solubilization from A-binds in salted groups during repeated freezing-thawing. The structural rearrangement caused by light salting facilitated the enlargement of water-holding space, transformation of tissue water, and tissue recoverability, improving water-holding capacity and texture properties of tilapia fillets during freezing-thawing. The finding provided novel insight into the improvement of quality properties of tilapia fillets by light salting when subjected to drastic temperature fluctuations. [ABSTRACT FROM AUTHOR]