Xiaorong Deng

This study employed an H2O2-induced model to elucidate the mechanisms by which oxidative stress regulates post-mortem muscle softening in Esox lucius. The results demonstrated that oxidative stress significantly accelerated textural deterioration, evidenced by a 42.41% reduction in shear force relative to the control at 120 h, and stimulated the degradation of desmin, actin, and troponin-T. Mechanistically, oxidative stress induced mitochondrial dysfunction, including reactive oxygen species accumulation, membrane potential dissipation, and enhanced mitochondrial permeability transition pore opening, which was accompanied by cytochrome c release and subsequent caspase-dependent apoptosis. Concurrently, oxidative stress induced mitophagy, as evidenced by increased Beclin-1 expression, an elevated LC3-II/LC3-I ratio, and reduced p62 abundance, with partial involvement of PINK1/Parkin signaling. Collectively, these findings indicate that oxidative stress accelerates myofibrillar degradation and muscle softening by disrupting the homeostatic balance between mitochondrial apoptosis and mitophagy, providing novel insights into the quality regulation of post-mortem fish.

This study systematically compared the quality deterioration dynamics of raw cow, goat, camel, and mare milk from Xinjiang, China, during refrigerated storage at 4°C for 7 days. While protein, fat, and lactose decreased significantly across all milk types (p < 0.05), species-specific patterns emerged. Camel milk exhibited the highest initial protein and fat, whereas mare milk contained the most lactose. Bioactive compounds, including lactoferrin, IgA, IgG, and lactoperoxidase (LPO), declined progressively, with camel milk showing the greatest lactoferrin loss (30.68% after 7 days). Notably, total and essential amino acids increased in cow and camel milk—suggesting microbial proteolysis—but decreased in goat milk. Protease and lipase activities initially rose before a slight decline, while LPO activity decreased markedly. Microbial counts surged in all samples, with camel and mare milk harboring the highest final loads, correlating with a pronounced pH drop and increased titratable acidity. Multivariate analysis revealed strong interconnections among nutrient degradation, enzymatic changes, microbial growth, and physicochemical deterioration. These findings provide critical comparative insights into species-specific refrigerated stability, offering a scientific basis for optimizing cold-chain management and processing strategies for diverse raw milk resources.

The Esox lucius is a high-quality fish species endemic to northern Xinjiang, having developed into a regional specialty industry with significant market value. However, during storage, it is prone to microbial growth that elevates biogenic amine levels, posing potential food safety risks. Therefore, this study systematically evaluated the effects of protamine—extracted from Esox lucius byproducts and used as a natural preservative—on the succession of microbial communities and biogenic amine accumulation in fish muscle under storage conditions of 4 °C, −3 °C, and −18 °C. A detection method for biogenic amines was also established. Results revealed characteristic changes in fish muscle microbial community α-diversity over storage time. Protamine treatment significantly delayed increases in total colony counts and microbial succession processes without altering the final dominant microbial community composition. By optimizing ultrasonic-assisted extraction and derivatization steps, an analytical method suitable for detecting eight biogenic amines in fish muscle matrices was established. Results indicate that protamine effectively inhibits the accumulation of all eight biogenic amines, with the 1% treatment group showing the most significant effect (p < 0.05). This study not only provides basis for the precise application of protamine in seafood preservation but also offers guidance for the resource utilization of aquatic by-products.

Ferritin, an emerging protein resource, has garnered significant attention in scientific research due to its biocompatibility and unique cavity structure capable of encapsulating bioactive compounds. This study aimed to optimize ultrasound-assisted extraction (UAE) for enhancing ferritin yield from northern pike liver byproducts and evaluate its potential as a nanocarrier for chlorogenic acid (CA). Through response surface methodology (RSM), the optimal UAE parameters were established as 200 W ultrasonic power, 1:3 solid–liquid ratio, and 25 min extraction time. Under these conditions, the ferritin extraction yield reached 139.46 mg/kg, representing a 4.02-fold increase compared to conventional methods (34.65 mg/mL). Electrophoretic analysis confirmed the electrophoretic purity of the extracted liver ferritin. Comprehensive characterization using UV-vis spectroscopy, FTIR, and fluorescence spectroscopy revealed preserved structural integrity of UAE-extracted ferritin. Homology modeling provided molecular insights into the ferritin architecture. Successful encapsulation of CA was achieved with an encapsulation efficiency of 13.25%, as quantified by HPLC. Analysis by DLS and ζ potential as well as TG and DSC showed that not only the thermal stability of CA was enhanced after ferritin encapsulation, but also that the ferritin remained stable with a cage-like structure. This investigation establishes UAE as an effective strategy for valorizing fish processing byproducts through high-yield ferritin extraction while demonstrating the protein’s functional capacity as a nanocarrier for bioactive compound delivery. The findings highlight the dual advantage of sustainable resource utilization and advanced delivery system development through this biotechnological approach.

As the most valuable protein in the sperm of testes tissues of Coregonus peled, Coregonus peled protamine (CPP) had a natural antibacterial and antiseptic effect, but its physicochemical properties and functions are easily affected by the ultrasound-assisted extraction process. In this study, ultrasound-assisted extraction of CPP was used to investigate the effects of different ultrasonic intensities (0, 3.03, 6.07, 9.10, 12.13, and 15.16 W/cm²) on the structural and functional properties of CPP. The results showed that at moderate ultrasonic intensity (9.10 W/cm²), the protein was the most successful, as it was subjected to cavitation shear and microjet by ultrasound, which resulted in changes in protein structure, moderate unfolding of peptide chains, and changes in the secondary and tertiary structures of CPP. SEM images confirmed the changes in the microstructure of CPP. Ultrasound oxidized the proteins to varying degrees with the highest sulfhydryl and carbonyl and surface hydrophobicity content at an ultrasonic intensity of 9.10 W/cm². At the same time, the solubility, antimicrobial activity, and heparin binding of CPP were affected. It is worth mentioning that the ultrasonicated CPP exhibited a stronger heparin-binding capacity compared to the non-ultrasonicated CPP. In conclusion, 9.10 W/cm² was determined as the optimal ultrasonic intensity parameter for this study. In conclusion, the incorporation of appropriate ultrasonic intensity in the acidic extraction process could help to improve the functional properties of CPP, and ultrasound-assisted protein extraction has emerged as a reliable technique capable of modifying the structure and function of CPP.