The present study aimed to evaluate the role of ascorbic acid in alleviating ammonia-induced muscle quality deterioration and to clarify its regulatory effects on apoptosis, texture, and flavor-related metabolites in rainbow trout (Oncorhynchus mykiss). The results demonstrated that ascorbic acid alleviated ammonia stress-induced inflammatory and apoptotic damage by regulating toll like receptor 5 (TLR5), myeloid differentiation primary response 88 (MyD88), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) expression, thereby contributing to the restoration of myofibrillar integrity, reduced extracellular gaps, and increased shear force from 14.18 N to 18.26 N (p < 0.05). Ascorbic acid modulated ammonia handling and ion-exchange responses by upregulating glutamine synthetase (GS) expression from approximately 2.3-fold to 6.7-fold and increasing ornithine and citrulline accumulation. Alterations in tricarboxylic acid cycle-related metabolites further suggested that energy metabolism may be involved in the physiological adaptation to ammonia stress. Meanwhile, the ascorbic acid reduced the accumulation of key off-flavor compounds (1-octene-3-alcohol and (E)-2-nonenal), attenuating the earthy–moldy and fishy flavor. This research proposes a potential strategy to improve muscle quality in live transportation.

Fresh channel catfish (Ictalurus punctatus) exhibit heightened susceptibility to microbial contamination, leading to an extremely limited shelf life. Consequently, this study evaluated the synergistic effects of high-voltage electric field (HVEF) treatment combined with Lotus seedpod procyanidins (LSPC) on microbial community dynamics and quality retention of fish fillets during refrigerated storage at 4 degrees C. The results showed that the combination of HVEF and LSPC significantly delayed quality deterioration of the fillets during storage. Specifically, compared to the control group (CK), the levels of drip loss and total volatile basic nitrogen were significantly decreased (p < 0.05) by 33.34 %, and 37.28 %, respectively, on day 12. Additionally, the combined treatment inhibited the accumulation of biogenic amines and prevented texture softening in the fillets. Microbial counts in the combined treatment group also decreased by 2.01 lg CFU/g on day 8 compared to the CK group. High throughput sequencing analysis further showed that HVEF combined with LSPC effectively suppressed the growth of spoilage bacteria such as Pseudomonas and unclassified Enterobacteriaceae. Based on these findings, the combination of HVEF and LSPC extended the shelf life of channel catfish fillets by 4 days, suggesting that this combined treatment could be an effective method for prolonging the shelf life of fresh fish fillets.

Transport stress during live fish transit is a major challenge in aquaculture. This study employed an integrated approach, combining serum biochemistry, liver histopathology, and muscle metabolomics, to assess the physiological and metabolic responses of Pelteobagrus fulvidraco to simulated transport at different temperatures (10, 14, 18, and 22 degrees C) and durations (0-24 h). Key findings revealed that transport stress significantly (p < 0.05) elevated serum levels of cortisol, glucose, and malondialdehyde, and induced marked liver damage. Metabolomic analysis of muscle tissue from sampled fish (n = 4 per group) demonstrated a time-dependent shift in the global metabolic response, transitioning from bile acid biosynthesis to purine metabolism. Furthermore, temperature significantly influenced the specific metabolic profile, with energy-related pathways dominating at 10 degrees C and 18 degrees C, while a shift towards nucleotide degradation products was notable at 14 degrees C. An integrated assessment identified 18 degrees C as the optimal transport temperature, causing the least physiological and metabolic disruption. These findings provide a scientific framework for optimizing transport conditions to mitigate stress and improve welfare in aquaculture, with the identified biomarkers holding promise for broader application in farmed fish species.

This study aimed to investigate the changes in the flavor profile of different operational units in preparing prepared catfish products using gas chromatography-mass spectrometry (GC-MS) and GC-ion mobility spectrometry (GC-IMS) techniques combined with statistical analysis. The results showed that channel catfish had different flavor characteristics at different processing stages. Among them, 1-hexanol, acetic acid-methyl ester, and 2-methylbutyric acid-methyl ester were the key volatiles in the curing stage, and octanol was the key volatile compound in the thawing process. These compounds may be connected to the oxidative degradation of 8cC20:1. Pentanone (D), propene, 2,3-pentanedione (D, M), 2,3-butanedione (D), 2-octanone, and phenylethanol are key volatiles during frying, thawing, and reheating. These compounds may be produced by oxidative degradation of C14:0, C14:1, C16:0, C16:1, C17:0, C18:0, 9cC18:1, and C18:3n-6. The butanal, heptanal, nonanal, 2-heptanone (D), 2-hexanone, 1-octen-3-ol, and ethyl acrylate were the key volatiles that were monitored throughout the process. These compounds mainly originated from lipid oxidative degradation. In addition, the reheating stage had the highest free amino acid content, which increased the saltiness and richness. Studying the changes in volatile compounds and their precursors during the processing of the samples improves the theoretical basis for the flavor regulation of pre-fried catfish.

Reasonable acclimation contributes to alleviate stress in fish transport and is one of the effective measures to improve fish welfare. Juvenile Siberian hybrid sturgeon (Acipenser baerii female x A. schrenckii male) were used as the research subject, and low-temperature acclimation group (15 degrees C, T15), control group (18 degrees C, T18) and hightemperature acclimation group (21 degrees C, T21) were set up. The results showed that with the extension of transport time, the content of blood cortisol and glucose increased in all groups, with the highest stress levels observed in the T21 group. Liver oxidative indicators increased significantly in all groups, while the activity of splenic lysozyme and immunoglobulin M showed an overall downward trend, which was negatively correlated with acclimation temperature. The TUNEL analysis results showed a positive correlation between the apoptosis index of splenic cells and the acclimation temperature. A total of 1621 differentially expressed genes (DEGs) were identified by RNA-sequencing-based transcriptomic profiling, which were enriched in pathways related to innate immunity. In the T21 group, the expression levels of most DEGs related to immunoglobulin and lysosomes were significantly downregulated, while the complement and coagulation cascade pathways were activated. In addition, the JNK signaling pathway plays an important role in acclimation and transport, inducing spleen apoptosis in fish. This study contributes to understanding the changes in biochemical characteristics of juvenile Siberian hybrid sturgeons under transport stress, and accumulating important biological data for transport optimization.

This study systematically investigated the concentration-dependent effects of chlorine dioxide (ClO2, 0-150 mg/L) on the structural and gelation properties of crayfish myofibrillar protein. The results demonstrated that ClO2 decomposition generated hydroxyl radicals (•OH) in a concentration-dependent manner, thereby inducing induced progressive protein oxidation. As the ClO2 concentration increased, a significant increase was observed in carbonyl content, dimeric tyrosine formation, and surface hydrophobicity, concomitant with a decrease in sulfhydryl groups, free amino groups, and protein solubility. Secondary structure analysis revealed a shift from α-helix to β-sheet and random coil. Moderate oxidation (<100 mg/L) enhanced gel strength through disulfide cross-linking., whereas concentrations exceeding 100 mg/L induced severe oxidation (e.g., methionine oxidation and cysteine trioxidation), resulting in coarse, disordered protein aggregation, significantly compromising gel water-holding capacity. Thus, 100 mg/L is recommended as the optimal threshold to balance disinfection efficacy and protein functionality in crayfish processing.

This study investigated the variations in protein, moisture distribution, and the quality of muscle, surimi, and gel in silver carp under ammonia stress and in response to mitigation measures. The samples included a group without ammonia stress or ascorbic acid (Control), a group with 30 mg/L ascorbic acid (AA), a group subjected to 10 mg/L ammonia stress (NG), and a group with 10 mg/L ammonia stress combined with 30 mg/L ascorbic acid (NA). The results revealed that ammonia stress led to a decrease in whiteness, water holding capacity (WHC), shear force, equilibrium elastic coefficient (E0), and decay elastic coefficient (E1), while pH, intermyocyte space, and protein oxidation in the muscle increased. However, the addition of ascorbic acid alleviated the deterioration in whiteness, WHC, gel strength, and protein structure in the gel. These findings offer valuable insights into improving the processing quality of muscle and enhancing its health benefits by mitigating stress and supporting gel formation in surimi.

Bioactive peptides are protein molecules known for their specific biological functions, offering promising applications across various fields including medicine, food, and cosmetics. Traditional approaches to the investigation of bioactive peptides typically encompass extraction, separation, purification, identification, and experimental evaluation. However, these methodologies are frequently subject to human-related variables, which consequently lead to reduced efficiency and compromised accuracy. Bioinformatics techniques, including computer simulation screening, quantitative structure-activity relationship (QSAR) analysis, and machine learning, have emerged as powerful tools in the field of bioactive peptide research. These advanced methodologies not only enhance the efficiency of bioactive peptide screening but also provide valuable insights into the underlying mechanisms of action of these peptides. This review discusses the identification, analysis, and evaluation of bioactive peptides through innovative bioinformatics technology while also highlighting traditional techniques that have been developed and improved. This review provides robust theoretical support and valuable references for future research and applications involving bioactive peptides.

Effective transport strategies are critical for the survival and welfare of juvenile Ictalurus punctatus, but the effects of pre-transport salt bath treatments remain uncertain. In this study, we systematically evaluated the effects of pre-transport salt bath acclimation at 0‰ (S1), 1‰ (S2), 5‰ (S3), and 9‰ (S4) salinity for 30 min on stress resilience and recovery in fingerlings during 12 h of simulated transport and 24 h of recovery. All fish survived, but total ammonia nitrogen (TAN) increased, and pH decreased in all groups, except S3, which showed significantly lower TAN and higher pH (p < 0.05). The S3 and S4 groups showed attenuated increases in serum cortisol and glucose, with S3 exhibiting the fastest return to baseline levels and stable serum sodium and potassium levels. Liver antioxidant enzyme activities in group S3 remained stable, with the lowest malondialdehyde (MDA) accumulation. Integrated biomarker response (IBR) and histological analyses demonstrated that S3 had the lowest systemic stress and tissue damage, whereas S1 and S4 displayed marked cellular disruption. These results indicate that a 5‰ salt bath applied prior to transport may improve water quality, mitigate stress responses, and preserve tissue integrity in juvenile channel catfish. Further studies are needed to confirm these findings in other species and under commercial transport conditions.

This study investigated the preparation and application of ultra-micro crayfish shell powder to enhance the quality of surimi gels. A combination of ball milling and irradiation techniques produced an innovative powder (MID) with reduced particle size and enhanced zeta potential, dispersibility, Ca2+ release, and hydrogen bonding energy (p < 0.05), while maintaining its composition. Adding 0.50 % MID to surimi gels resulted in optimal improvements, enhancing gel strength and texture as well as elasticity. MID also increased the water holding capacity (WHC), decreased water mobility, and resulted in a dense and ordered microstructure. Fourier transform infrared spectroscopy indicated improvements were due to increased intermolecular non-covalent bonding interactions. Electronic nose analysis showed MID reduced aromatic compounds and organosulphides, preserving flavor and reducing the fishy taste. Electronic tongue analysis revealed an increase in fresh flavor response. The preparation method significantly enhanced the quality and sensory properties of surimi gels.

The quality of Yusheng (a raw fish delicacy) is a critical determinant of consumer acceptance. This study investigated the effect of 5 mg/L gallic acid (GA) on muscle quality of largemouth bass (Micropterus salmoides), a key species for Yusheng production, based on the influence on the brain neurotransmitter-gut microbiota axis during 28 days of temporary rearing, with the muscle fiber morphology and intestinal structure being assessed every 7 days to evaluate potential improvements in muscle quality. Histological analysis revealed denser muscle fiber organization and more uniform myofibrillar structure in the 5 mg/L GA group; the better intestinal morphology structure was in the fish after 21 days of temporary rearing. The fish after 5 mg/L GA temporary rearing for 21 days exhibited significantly higher muscle pH, whiteness value and shear force along with a lower pressurized water loss rate, and the activities of superoxide dismutase and catalase and the contents of glutathione and malondialdehyde showed slowing down. Furthermore, integrated high-throughput analyses of neurotransmitters, gut microbiota, and muscle biomarkers revealed that GA induced alternation in the signal transmission of the neurotransmitter-gut microbiota axis, downregulated Ornithine Decarboxylase 1 (ODC1) and Arginase 2 (ARG2) expression, increased ornithine content, decreased arginine content and decreased putrescine production. The research demonstrated that temporary rearing with 5 mg/L GA for 21 days enhanced the muscle quality of largemouth bass through promoting antioxidant activities and induced alteration in signal transmission of the neurotransmitter gut microbiota axis to regulate the formation pathway of putrescine, which provides a theoretical basis for the systemic purification of premium Yusheng.

The research examines how myofibrillar protein emulsion with different pre-emulsified soybean oil (PESO) levels (0%, 6%, 8%, and 10%) influences surimi gel across seven freeze-thaw (F-T) cycles. The addition of PESO led to a notable improvement in gel strength and whiteness. Significant increases were also noted in hardness, water-holding capacity (WHC), and the maximum relaxation time of the immobilized water (p < 0.05). The findings revealed an increase in both the storage modulus (G') and the loss modulus (G″), while secondary and microstructural assessments demonstrated a stronger and more organized gel network. As the gel was subjected to successive F-T cycles, its overall quality declined progressively. An increase in the number of F-T cycles resulted in a steady decrease in gel hardness, WHC, gel strength, and lightness; however, there was no significant change in gel springiness (p > 0.05). Notably, when the soybean oil concentration in the pre-emulsion was set at 8%, the surimi achieved optimal G', hardness, and gel strength after enduring seven F-T cycles, with its WHC peaking at a significant 76%. The findings demonstrate that the addition of PESO effectively improves surimi gel properties and mitigates lipid loss during rinsing, providing insights for enhancing surimi product quality.

Rice-field eel (Monopterus albus) slices, an important aquatic product in Southeast Asia, are prone to spoilage and deterioration during cold chain storage. In this study, the effects of a composite preservative (ε-polylysine, Vitamin C (Vc), epigallocatechin gallate (EGCG), and phloretin) on the muscle quality (color, texture, water holding capacity (WHC)) of rice-field eel slices during refrigeration storage at 4 °C for up to 7 days was investigated, and the underlying mechanism was elucidated by the integrated microbiome and metabolomics, in addition to Elisa and Low-Field Nuclear Magnetic Resonance (LF-NMR). After 7 days of storage, the WHC, shear force, and a* decreased by 11.39%, 34.37%, and 49.20% in treated samples, and by 19.18%, 38.38%, and 54.87% in control samples, respectively. The addition of the composite preservative significantly increased Hexokinase, Pyruvate kinase, and Creatine kinase, while it decreased the total viable count (TVC), total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substance (TBARS), and Lactic acid. Preservative treatment maintained the moisture content of the eel slices during storage and prevented bright red oxymyoglobin from transforming into brown metmyoglobin. Microbiota composition (especially Pseudomonas) and metabolic pathways (including amino acid and its metabolites, nucleotide and its metabolite, and organic acid and its derivatives, etc.) were obviously altered by the preservative treatment. Pseudomonas, tryptophan-aspartic acid (Trp-Asp), D-Glucose 6-phosphate, Succinic Acid, Biliverdin 1, 5-Diaminopentane, and Tyramine, etc., are potential biomarkers for the quality changes of eel slices during refrigeration. These findings provide an in-depth understanding of the improvement of the eel slice quality during refrigeration storage by the composite preservative.

A composite emulsion was created by incorporating 4% (m/m) soybean protein isolate and 25% (m/m) soybean oil into a mixture containing 0.5% (m/m) chitosan and 1% (m/m) thymol. By comparing changes in total volatile basic nitrogen content, aerobic bacteria count, pH, biogenic amines content, volatile components, and microbial species in fish meat after storage at different times, the study explored the impact of composite emulsions on the quality of largemouth bass fillets during storage. Our results show that this composite emulsion effectively delayed the increase in total volatile basic nitrogen content, aerobic bacterial count, putrescine, cadaverine, and histamine contents of largemouth bass fillets during storage at 10 °C, extending the shelf life to 16 days. The primary spoilage compounds observed during the storage of largemouth bass fillets were isopentyl butyrate-M, 3-methylpentanoic acid, 4-methyl-2-pentanone, 4-methylthiazole, ethyl 2-methylbutyrate, and 2-butanol-D. Furthermore, the addition of the emulsion during storage effectively reduced the relative abundance of Aeromonas and Citrobacter, while also decreasing the generation of isoamyl butyrate-M and 2-methylbutyraldehyde-M. In conclusion, the combination of chitosan and thymol coating not only delayed the deterioration of largemouth bass fillet quality during storage but also inhibited the growth of spoilage bacteria and reduced the production of volatile spoilage compounds. Therefore, this study can provide valuable reference for the preservation of largemouth bass and the application of low temperature logistics and transportation for aquatic products.

To evaluate the quality characteristics and steaming suitability of key freshwater fish species, we conducted a comprehensive study on four high-yield varieties (snakehead, silver carp, channel catfish, and bass) representing over 20 % of China's freshwater aquaculture output. We focused on their approximate composition, nutrition, and microstructure and explored the effects of salting time (0-4 h), salt concentration (0-4 %), and steaming time (4-8 min) on cooking loss, texture, and water distribution. The optimal conditions were achieved with salt concentration of 2-3 %, salting time of 2-3 h, and steaming time of 6-7 min. The steaming quality ranked as snakehead > channel catfish > bass > silver carp. This study provides theoretical foundations for enhancing raw material utilization efficiency and developing processed products in the freshwater fish industry.

Transportation practices, especially under high-density conditions, induce significant physiological stress in yellow catfish (Pelteobagrus fulvidraco), adversely affecting their health and product quality. This study examines the effects of transportation density (defined as fish biomass (kg) to water volume (m3) ratios of 1:4, 1:8, 1:12, and 1:16) and duration (0, 3, 6, 12, 24, 48, 72 h) on oxidative stress biomarkers, immune responses, and tissue damage. In high-density groups (1:4 and 1:8), mortality occurred after 48 h and 72 h, respectively, with survival rates declining sharply. Elevated serum aspartate aminotransferase and alanine aminotransferase levels indicated liver damage, while increased blood urea nitrogen and creatinine levels revealed impaired kidney function, particularly severe in the 1:4 density group. Cortisol and glucose levels surged in high-density groups, reflecting metabolic disruption. Although antioxidant enzymes (Catalase, Superoxide dismutase) initially increased with density, they were overwhelmed in high-density groups, as evidenced by elevated malondialdehyde levels, indicating lipid peroxidation. Histopathological analysis confirmed tissue damage in high-density groups, including hepatic vacuolation, gill filament curling, and intestinal villi rupture. High-density transport significantly compromises the survival, physiological function, and tissue integrity of yellow catfish. To enhance the survival rate and welfare of yellow catfish during transportation, a comprehensive assessment was conducted based on stress indicators and tissue damage.

Thermal treatment is an essential processing method in crayfish processing. This study analyzed the changes in lipids and volatile compounds in crayfish muscle subjected to three thermal processes: boiling (BO), air-frying (AF), and boiling combined air-frying (BO-AF). Aldehydes and heterocyclic compounds were found to be the predominant volatile compounds in crayfish muscle during thermal processing and storage. The intensity of lipid oxidation (POV, TBARS and p-AnV) was greatest in AF, and was notably lower in BO-AF. the total concentration of free fatty acids (FFAs) was highest in the AF group (4.14 mg/g) after processing, followed by BO (3.26 mg/g) and BO-AF (2.04 mg/g). During storage, the FFAs content gradually decreased, with generally lower levels observed at 65 °C compared to 45 °C. A total of 383 phospholipid species were identified, phosphatidylethanolamine being the primary difference lipid type in BO (26.7 %) and AF (36.7 %), while fatty acids were the main differential lipid types in BO-AF group, under the comparison between processed and stored. Overall, the BO-AF method improved the flavor sensory and decreased lipid oxidation, compared to the other two methods. These findings provide valuable insights into the effects of different thermal processing and storage methods on the quality and safety of crayfish muscle.

To assess the feasibility of developing fish scale peptides as melanin inhibitors, peptides were extracted from the scales of silver carp (Hypophthalmichthys molitrix). By performing selenocysteine modification, molecular docking, and in vitro analyses, it was identified SGP-C(Se) as the peptide with the strongest antioxidant activity. Further studies included tyrosinase (TYR) inhibition assays, ultrafast kinetic analysis, and validation experiments using B16 melanoma cells. The results revealed that SGP-C(Se) (2 mM) had a strong antioxidant activity, with & sdot;OH and DPPH & sdot; radical scavenging rates reaching 98.20 % and 97.66 %, respectively, and at the same concentration induced 99.27 % tyrosinase inhibition. In molecular dynamics, the SGP-C (Se)-TYR system was stable, and its fluorescence lifetime (tau 1 = 4.40 ns) was shorter than that of SGP-C (Se) (tau 2 = 5.54 ns) and TYR (tau 3 = 8.00 ns). At 0.5 mM, SGP-C(Se) significantly reduced the levels of reactive oxygen species and cAMP in B16 cells, down-regulated the expression of proteins associated with the Wnt/beta-catenin, cAMP-CREB, and MAPK signalling pathways, and suppressed the mRNA transcription of MITF, TYR, TRP-1, and TRP-2. These findings highlight the potential of SGP-C(Se) as a melanin inhibitor for biological applications.