Search Results (269)

This study focused on proteins derived from beef to minimize the influence of seasonings when developing a method for determining the geographical origin of seasoned beef samples. The seasoning used was sweetened soy sauce containing sugar, soy sauce, mirin and sake. The water-soluble fraction was extracted as a cleaning step for the sample, followed by extraction of the myofibrillar protein fraction. No significant differences were observed in the carbon, nitrogen and oxygen isotope ratios of the proteins extracted from the defatted raw and cooked beef samples. The carbon, nitrogen and oxygen isotope ratios of the protein fraction extracted from defatted beef were positively correlated with the corresponding ratios in the defatted whole beef samples. These results suggest that the protein fractions were mainly composed of beef proteins, and that the addition of auxiliary materials did not affect this. To verify the possibility of determining the geographic origin of beef, the carbon, nitrogen and oxygen isotope ratios of proteins extracted from beef from the United States (U.S.), Australia and Japan were analyzed. The carbon isotope ratios of proteins extracted from U.S. beef were higher than those of Australian and Japanese beef. Additionally, the oxygen isotope ratios of proteins extracted from Australian beef were higher than those of beef from the U.S. and Japan. These results suggest that it may be possible to trace the geographical origin of beef products cooked with seasonings by extracting proteins. Full article

This study investigates FLNC mutations in Chinese cardiomyopathy patients. Background: Inherited cardiomyopathies, including dilated cardiomyopathy (DCM), hypertrophic cardiomyopathy (HCM), restrictive cardiomyopathy (RCM), and arrhythmogenic right ventricular cardiomyopathy (ARVC) are major heart failure causes. FLNC, critical for muscle structure, is implicated in myofibrillar myopathy and isolated DCM (3–4% cases) with ventricular arrhythmias. Missense variants are linked to HCM and protein aggregation. A cohort of 25 patients with pathogenic/likely pathogenic FLNC mutations (2022–2025, Beijing Anzhen Hospital) underwent whole-exome sequencing (WES) using IDT kit 1.0/Hiseq 4000. Variants were classified via the American College of Medical Genetics and Genomics (ACMG) guidelines. Clinical data (echocardiography, CMR, labs) and follow-up data (prognosis, meds, and family history) were collected. The statistics used SPSS (p < 0.05). The mean age was 38 ± 14.6 years (13 males). There were 25 FLNC mutations: 12 single nucleotide polymorphisms (SNPs), 5 deletions, 2 duplications, and 3 deletion-insertions, classified as 6 pathogenic, 16 likely pathogenic, and 3 variants of uncertain significance (VUS). Diagnoses: 24% dilated cardiomyopathy (DCM), 8% hypertrophic cardiomyopathy (HCM), and 4% left ventricular non-compaction. Nonsense mutation carriers exhibited significantly higher tricuspid regurgitation prevalence compared to frameshift mutation carriers (6/9 vs. 2/10; p = 0.04). Echocardiography revealed reduced left ventricular ejection fraction (LVEF) (41.5 ± 14.1%), with statistically significant differences in fractional shortening (p = 0.024) and aortic root diameter (p = 0.028). Pedigree analysis confirmed that a frameshift mutation (LP) co-segregated with familial DCM and was associated with severe phenotypes, including sudden cardiac death. Furthermore, nonsense FLNC mutations correlated with increased tricuspid regurgitation severity, smaller aortic root dimensions, and reduced pulmonary artery flow velocity. Full article

This study employed a multi-technique approach to investigate the structural and conformational changes in proteins in Meretrix lyrata (M. lyrata) adductor, foot, and siphon tissues during boiling. Data-independent acquisition (DIA) quantitative proteomics was utilized to identify differentially expressed proteins (DEPs) in six temporal comparison groups (20–0 s, 40–20 s, 60–40 s, 80–60 s, 100–80 s, and 120–100 s). The results showed that key myofibrillar proteins, including myosin heavy chain, paramyosin, and actin, exhibited tissue-specific expression patterns, while low-molecular-weight degradation fragments (<17 kDa) appeared with prolonged heating. Turbidity measurements peaked in adductor and siphon tissues at 60 s and in foot tissue at 80 s. Heating resulted in a narrowed particle size distribution (100–1000 nm), and a decreased zeta potential, indicating a reduction in protein surface charge. Fourier transform infrared spectroscopy revealed hydrogen bond disruption and secondary structure transitions, marked by a reduction in α-helix content with a corresponding increase in β-sheet and random coil structures. In total, 6527 proteins were identified, and Gene Ontology (GO) enrichment analysis highlighted the DEPs’ involvement in biological regulation and metabolic processes. Collectively, these results provide comprehensive characterization of protein denaturation, degradation, and structural reorganization in M. lyrata tissues during the boiling process. Full article

Myofibrillar protein (MP) aggregation in solutions with NaCl concentrations below 0.3 M results in poor solubility. Ultrasound-assisted glutaminase treatment (UGT) was applied to improve MP solubility in a low-salt solution (containing 0.1 M NaCl). The solubility increased with ultrasonic power and time, peaking at 44.34% (480 W, 15 min) and reaching 61% after UGT. Subsequently, the effect of post-sonication heat treatment (60 °C, 30 min) on the physicochemical and structural characteristics of ultrasound-enzyme treated MP (UEMP), prepared under specific ultrasonic conditions (480 W, 20 min), was systematically investigated. The findings revealed that UEMP exhibited higher hydrophobicity, sulfhydryl content, and turbidity, but reduced particle size, ζ-potential, and fluorescence, suggesting disulfide disruption and exposure of hydrophobic residues. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed weakened high-molecular weight bands and intensified low-molecular weight bands. Fourier-transform infrared spectroscopy confirmed these structural rearrangements, with a blue-shifted amide A band and decreased amide I intensity. Heating further increased the hydrophobicity and fluorescence without altering the size, ζ-potential, or molecular weight. The red shift in the amide A band suggests reinforced local ordering. Rheology analysis showed non-Newtonian shear-thinning behavior, which was unchanged by UGT or heating. Collectively, UGT with moderate heating enhances MP solubility and thermal stability by disrupting stabilizing bonds and modulating the structure. Full article

Background and Clinical Significance: FLNC encodes filamin C, a muscle-scaffolding protein crucial for cardiac integrity. Pathogenic FLNC variants cause diverse cardiomyopathies (hypertrophic, dilated, restrictive, and arrhythmogenic) and myofibrillar myopathies, but their role in congenital cardiac malformations is unclear. Notably, FLNC has not been implicated in structural defects such as Tetralogy of Fallot (TOF) to date. Case Presentation: Two fetuses from the same family were prenatally diagnosed with TOF via ultrasound. The trio whole-exome sequencing of the second fetus and her parents identified a novel heterozygous truncating FLNC variant (NM_001458.5:c.1453C>T, p.Q485*). Sanger sequencing confirmed the same variant in the earlier TOF fetus. The mother carried the variant but was asymptomatic. In vitro mutagenesis in rat cardiomyocytes showed that the mutant FLNC construct produced markedly reduced FLNC proteins compared to the wild type and did not form abnormal cytoplasmic aggregates. Conclusions: We report on a novel FLNC truncating variant associated with fetal TOF, extending the spectrum of FLNC-related cardiac anomalies. The variable outcomes among variant carriers—from fetal TOF to adult cardiomyopathy or no clinical manifestations—underscore the complex genotype–phenotype correlations of filaminopathy. This case highlights the importance of comprehensive genetic evaluation in families with diverse cardiac phenotypes and suggests that additional genetic factors likely influence phenotypic expression. Full article

This study investigates the potential of an undervalued cephalopod species, Eledone moschata, for producing a freeze-dried protein concentrate via acid solubilisation and isoelectric precipitation. Although nutritionally rich, the processing route significantly affected the aggregation state of the recovered proteins, as demonstrated by differential scanning calorimetry (DSC) and SDS–PAGE electrophoresis. We systematically examined pretreatments of the lyophilised protein concentrate (PC) by dispersing it across a pH range (2–10) and applying ultrasonication (US), characterising the resulting aggregates in terms of protein solubility, surface hydrophobicity, dynamic light scattering (DLS), and ζ-potential. Subsequently, ultrasound-treated protein dispersions at different pH values were used to produce protein–quercetin nanoparticles (PQ), which were analysed for particle size (DLS), yield, and quercetin entrapment efficiency. PQ dispersions at pH 2, 4, and 7 were evaluated as stabilising agents in US-treated sunflower oil emulsions containing 10% oil and were characterised by rheological properties, microstructure, and DLS particle sizing. Confocal laser scanning microscopy (CLSM) revealed that nanoparticles at pH 2 produced small, uniformly distributed fat droplets with a particle diameter of 1.5 μm. This study provides insights into how processing conditions modulate the structural and interfacial behaviour of cephalopod proteins and highlights their potential application in designing low-fat, fluid emulsions for innovative food formulations. Full article

The freshwater drum (Aplodinotus grunniens) is a promising aquaculture species due to its strong environmental adaptability, tolerance to low temperatures, rapid growth rate, high nutritional value, high-quality texture (garlic-clove-shaped flesh), and absence of intermuscular bones. Nevertheless, processing technologies related to freshwater drum remain largely unexplored. Salting pretreatment serves as a viable strategy for enhancing the quality attributes of frozen fish products. This study investigated the effects of different sodium chloride (NaCl) pickling concentrations (0.25, 1, and 3 mol/L) on the physicochemical properties and quality attributes of frozen–thawed freshwater drum (Aplodinotus grunniens). Results indicated that elevated NaCl concentrations (1–3 mol/L) significantly (p < 0.05) shortened the transit time through the maximum ice crystal formation zone during freezing, effectively mitigating structural damage to myofibrillar networks. As the NaCl concentration increased from 0 to 3 mol/L, the water content decreased from 71.26 ± 0.22% to 68.64 ± 0.50%, while the salt content increased from 0.31 ± 0.01% to 8.46 ± 0.12%. Pickling pretreatment markedly enhanced water-holding capacity and improved texture profiles, including hardness, springiness, gumminess, and chewiness. Histological analysis revealed preserved myofibril integrity in high-salt-treated samples, supported by reduced fluorescence intensity of myofibrillar proteins, indicating mitigated freeze-induced denaturation. Low-field NMR confirmed salt-induced redistribution of water states, with decreased free water proportion. Our results identify that pretreatment with NaCl at concentrations ≥ 1 mol/L is an effective strategy to preserve the post-thaw quality. Due to 3 mol/L NaCl resulting in a relatively high salt content, 1 mol/L NaCl pretreatment is more suitable for maintaining the quality of freeze–thawed freshwater drums. Full article

In this study, whey protein isolate–soybean lecithin-encapsulated vitamin A emulsion (V_A-WSE) with different oil-to-water ratios was prepared and characterized. The impact of V_A-WSE on the physicochemical characteristics of Nemipterus virgatus surimi at varying concentrations was determined. The V_A-WSE emulsion exhibited the best stability when the oil-to-water (O:W) ratio was 1:1 (w/w). Composite gels prepared by mixing V_A-WSE (O:W = 1:1, w/w) with surimi at different ratios showed significantly improved gel properties. In particular, the hardness, chewiness, gel strength, and water-holding capacity of the composite gel with a V_A-WSE concentration of 8% (w/w) reached the highest values of 2629.00 g, 2051.27 g, 292.16 g·cm, and 87.10%, respectively. Similarly, the observed voids in the microstructural images gradually decreased with rising V_A-WSE concentration and were the smallest in the 8% sample group. Surimi gels showed remarkably enhanced hydrogen bonds in the V_A-WSE concentration range of 0–8%, increasing from 0.001 to 0.025 mg/mL (p < 0.05). Furthermore, it was observed that the energy storage modulus (G′) was larger than the loss modulus (G″), suggesting the dominant elastic characteristics of the composite gels. The solubility and total sulfhydryl group contents significantly increased from 30.33 to 88.29% and from 4.90 to 28.19 nmol/mg, respectively. In summary, V_A-WSE can promote the unfolding of the myofibrillar protein (MP) structure and improve the gel properties of surimi gels. These results support the development of functional surimi products. Full article

This study aims to improve the gel properties of Nemipterus virgatus myofibrillar protein (MP) emulsion gels by Curdlan (Cur) and investigate the effect of the emulsion gels on the quality of emulsified surimi gels. The effects of different concentrations of Cur on the gel properties of MP emulsion gels were investigated. Fourier transform infrared (FTIR) results indicated that intermolecular interactions between Cur and MP were primarily hydrogen bonds. Cur enhanced the adsorption capacity of MP at the oil/water interface, inducing the formation of a more uniform and dense composite network structure in Cur/MP emulsion gels. Adding 6% (w/v) of Cur significantly increased the hardness, gel strength, water-holding capacity (WHC) and rheological properties of the gel. In addition, microstructural images showed that MP formed a complex interpenetrating network with Cur, thus enhancing the gel network skeleton. Low-field NMR confirmed that the addition of Cur decreased water mobility in the emulsion gel system. Compared to the direct addition of oil, the application of Cur/MP emulsion gels to surimi significantly improved the texture, gel strength, and WHC of the surimi gel. These findings provide a reference for the development of myofibrillar protein emulsion gels and broaden their potential application in the food industry. Full article

Background/Objectives: Several sequences for magnetization transfer contrast (MTC) imaging are available, from indices of MTC ranging from quantitative magnetization transfer (qMT) that yields the macromolecular fraction to simple ratios of signal intensities with and without a magnetization transfer (MT) pulse. Aging muscle undergoes changes including an increase in fibrosis and adipose accompanied by fiber atrophy and loss. The objective is to evaluate five MTC sequences to study age-related differences in muscle tissue composition. Methods: The lower leg (calf) of 15 young (8M/7F, 25.8 ± 3.7 years) and 9 senior subjects (5F/4M, 68.4 ± 3.3 years) was imaged with the following sequences: multi-offset qMT fit to the Ramani and Yarnykh models, single-offset qMT two-parameter fit to the Ramani model, a semi-quantitative MT_sat sequence, magnetization transfer ratio (MTR), and MTR-corrected (MTR_corr) for B1 inhomogeneities. T1 mapping was also performed. Statistical analysis was performed to identify significant age-related and regional (intermuscular) differences. Results: Significant age-related decreases (p < 0.001) in macromolecular fraction (from two-parameter fit), MT_sat, MTR, and MTR_corr were identified. A significant age-related increase in T1 (p < 0.001) was also identified. Pearson correlation coefficients between T1 and MTC indices were weak to moderate but significant. Conclusions: Age-related decreases in MTC may reflect that loss of myofibrillar proteins dominates the increase in collagen content with age. Further, the modest correlation of MTC indices with T1 indicates that all the age-related differences in MTC cannot be explained by an increase in inflammation. The MT_sat sequence was identified as the most clinically relevant in terms of acquisition speed, post-processing simplicity, and ability to identify age-related differences in macromolecular fractions. Full article

The giant squid (Dosidicus gigas) is an abundant marine species with high protein content, making it a promising resource for the food and biomaterial industries. This study aimed to investigate the effect of temperature (25–100 °C) on the structural changes in sarcoplasmic, myofibrillar, and stromal proteins isolated from squid mantle. Fourier-transform infrared spectroscopy (FT-IR) and circular dichroism (CD) were employed to monitor modifications in secondary structure, while field emission scanning electron microscopy (FE-SEM) was used to examine morphological characteristics. The FT-IR analysis revealed temperature-induced transitions in amide I, II, and A bands, indicating unfolding and aggregation processes, particularly in myofibrillar and stromal proteins. CD results confirmed a loss of α-helix content and an increase in β-sheet structures with rising temperature, especially above 60 °C, suggesting progressive denaturation. FE-SEM micrographs illustrated clear morphological differences: sarcoplasmic proteins displayed smooth, amorphous structures; myofibrillar proteins exhibited fibrous, porous networks; and stromal proteins presented dense and layered morphologies. These findings highlight the different thermal sensitivities and structural behaviors of squid muscle proteins and provide insight into their potential functional applications in thermally processed foods and bio-based materials. Full article

This study aimed to assess how sex and age influence the physicochemical and technological properties of the longissimus thoracis et lumborum muscle in Botucatu rabbits. Ten samples were used from each experimental group (females and males 3 and 12 months old). Color (L*, a*, and b*), pH, water-holding capacity, cooking weight loss, shear force, percentage of collagen (soluble, insoluble, and total), myofibrillar fragmentation index, sarcomere length, cholesterol concentrations, lipid oxidation, and chemical composition were evaluated. Sex influenced (p < 0.05) the chemical composition of the meat; young females presented meat with a higher concentration of lipids and cholesterol than males of the same age; however, the opposite results were obtained with the meat of 12-month-old rabbits. Age also influenced the meat’s characteristics: older rabbits had meat with more intense red and yellow colors and longer sarcomere length. In terms of chemical composition, 12-month-old rabbits had higher protein and lower soluble collagen and mineral matter compared to younger rabbits. Overall, age impacted the physicochemical properties, with older rabbits exhibiting more opaque, reddish meat, higher insoluble collagen, and lower moisture content. In addition, the influence of sex, especially on the chemical composition of meat in rabbits, must be emphasized. Full article

Background: The process of muscle protein synthesis (MPS) plays a pivotal role in the enhancement of muscle function. Following a bout of exercise, the rate of MPS experiences an elevation for a brief period, known as the “anabolic window.” Despite whey protein supplementation has been demonstrated to augment the post-exercise anabolic window, the optimal timing and dosage remain controversial. Therefore, the present systematic review and meta-analysis were conducted to evaluate the effects of whey protein supplementation on post-exercise MPS and its protein kinase B (AKT)/mammalian target of the rapamycin (mTOR) pathway in healthy adults. Methods: Following PRISMA guidelines, this review included 21 RCTs, with 15 studies subjected to meta-analysis and 6 studies to qualitative analysis. Eligible studies examined myofibrillar fractional synthetic rate (FSR) or the AKT/mTOR pathway-related protein phosphorylation levels in muscle biopsy samples. Results: The combination of whey protein supplementation and exercise has been shown to significantly enhance FSR (Hedge’s g = 1.24, 95% CI: 0.71–1.77; p < 0.001), with increases ranging from 1.3 to 1.6 folds when consumed immediately after exercise and up to 2.5 folds when given 45 min prior to multiple-set resistance exercise. A dose-dependent increase in FSR was observed in response to whey protein supplementation, ranging from 10 to 60 g. In comparison to the placebo group, whey protein supplementation enhanced the phosphorylation levels of AKT, mTOR, eukaryotic translation initiation factor 4E-binding protein-1 (4E-BP1), 70 kDa ribosomal protein S6 kinase (p70S6K), and ribosomal protein S6 (rpS6) at 1–2 h post-exercise. Phosphorylation levels of p70S6K and rpS6 decreased 4–5 h after exercise. Conclusions: The combination of whey protein supplementation and exercise improves MPS in a time- and dose-dependent manner. Consumption of 20–40g of whey protein before multiple sets of resistance exercise may enhance myofibrillar FSR and activate the AKT/mTOR pathway, thereby augmenting MPS and extending the anabolic window. Full article

Freshwater surimi typically exhibits poor gel-forming capability and is prone to gel deterioration, limiting its applications in food products. This study successfully prepared silver carp surimi gels with improved gel strength and water-holding capacity (WHC) using carboxymethyl konjac glucomannan (CKGM) as a functional modifier. Furthermore, the regulatory mechanism of CKGM with different degrees of substitution (DS) on the gel properties of silver carp surimi was systematically investigated. Results demonstrated that DS significantly influenced gel strength, WHC, and microstructure. CKGM (DS = 0.21%) substantially enhanced the gel strength and WHC through strengthened hydrophobic interactions and hydrogen-bond networks. However, CKGM with a higher DS (0.41%) induced a steric hindrance effect, decreasing elastic modulus and WHC and resulting in a more porous gel network. Raman spectroscopy analysis revealed that CKGM facilitated the conformational transition of myofibrillar proteins from α-helix to β-sheet, thereby improving the density of the gel network. The study provides theoretical foundations and technical guidance for the quality improvement of surimi products. Full article