Changes In Myofibrillar Proteins Research Articles

Changes in Collagen across Pork Tenderloin during Marination with Rosehip Nanocapsules

The objective of this study was to prepare zein–gum Arabic nanocapsules with rosehip oil (NC-RH), apply them to pork tenderloin, and analyze the changes in collagen structure under different conditions (pH 6.5 and 4.0) and temperatures (25 °C and 4 °C). NC-RHs were prepared using the nanoprecipitation method. Nanocapsules had a particle size of 423 ± 4.1 nm, a polydispersity index of 0.125 ± 3.1, a zeta potential value of −20.1 ± 0.41 mV, an encapsulation efficiency of 75.84 ± 3.1%, and backscattering (ΔBS = 10%); the antioxidant capacity of DPPH was 1052 ± 4.2 µM Eq Trolox and the radical scavenging capacity was 84 ± 0.4%. The dispersions exhibited Newtonian behavior at 25 °C and 4 °C. Incorporating NC-RH into acid marination benefited the tenderness, water-holding capacity, and collagen swelling, and favored changes in myofibrillar proteins corroborated with histological tests. The conditions with the best changes in pork tenderloin were a pH of 4.0 at 4 °C with an NC-RH-administered 11.47 ± 2.2% collagen area. Incorporating rosehip nanocapsules modifies collagen fibers and can be applied in pork marinades to increase the shelf life of a functional product.

Myofibrillar protein hydrolysis under hydroxyl radical oxidative stress: Structural changes and their impacts on binding to selected aldehydes

In this study, a hydroxyl radical oxidation system was established to simulate the oxidation process in fermented meat products. This system was employed to examine the structural changes in myofibrillar proteins (MPs) resulting from tryptic hydrolysis after a hydroxyl radical oxidative regime. The effect of these changes on the ability of MPs to bind selected aldehydes (3-methyl butanal, pentanal, hexanal, and heptanal) was also investigated. Moderate oxidation (H2O2 ≤ 1.0 mM) unfolded the structure of MPs, facilitating trypsin-mediated hydrolysis and increasing their binding capacity for the four selected aldehydes. However, excessive oxidation (H2O2 ≥ 2.5 mM) led to cross-linking and aggregation of MPs, inhibiting trypsin-mediated hydrolysis. The oxidised MPs had the best binding capacity for heptanal. The interaction of the oxidised trypsin-hydrolysed MPs with heptanal was driven by hydrophobic interactions. The binding of heptanal affected the structure of the oxidised trypsin-hydrolysed MPs and reduced their α-helix content.

Thawed drip and its membrane-separated components: Role in retarding myofibrillar protein gel deterioration during freezing-thawing cycles

Myofibrillar proteins are crucial for gel formation in processed meat products such as sausages and meat patties. Freeze-thaw cycles can alter protein properties, impacting gel stability and product quality. This study aims to investigate the potential of thawed drip and its membrane-separated components as potential antifreeze agents to retard denaturation, oxidation and gel deterioration of myofibrillar proteins during freezing-thawing cycles of pork patties. The thawed drip and its membrane-separated components of > 10 kDa and < 10 kDa, along with deionized water, were added to minced pork at 10 % mass fraction and subjected to increasing freeze–thaw cycles. Results showed that the addition of thawed drip and its membrane separation components inhibited denaturation and structural changes of myofibrillar proteins, evidenced by reduced surface hydrophobicity and carbonyl content, increased free sulfhydryl groups, protein solubility and α-helix, as compared to the deionized water group. Correspondingly, improved gel properties including water-holding capacity, textural parameters and denser network structure were observed with the addition of thawed drip and its membrane separation components. Denaturation and oxidation of myofibrillar proteins were positively correlated with gel deterioration during freezing-thawing cycles. We here propose a role of thawed drip and its membrane separation components as cryoprotectants against myofibrillar protein gel deterioration during freeze-thawing cycles.

Inhibitive effect of trehalose and sodium pyrophosphate on oxidation and structural changes of myofibrillar proteins in silver carp surimi during frozen storage

This work investigated the cryoprotective effect of trehalose (TH) and sodium pyrophosphate (SPP) alone and in combination on myofibrillar protein (MP) oxidation and structural changes in silver carp surimi during 90 days of frozen storage (-20 °C). TH combined with SPP was significantly more effective than single TH or SPP in preventing MP oxidation (P < 0.05), showing a higher SH content (6.05 nmol/mg protein), and a lower carbonyl (4.24 nmol/mg protein) and dityrosine content (1280 A.U.). SDS-PAGE results indicated that TH combined with SPP did not differ significantly from TH and SPP in inhibiting protein degradation but was more effective in inhibiting protein crosslinking. Moreover, all cryoprotectants could stabilise the secondary and tertiary structures and inhibit unfolded and aggregation of MP, with the combination of TH and SPP being the best. It's worth noting that TH combined with SPP had a synergistic effect on inhibiting the decrease in α-helix content and gel-forming ability, and the increase in surface hydrophobicity. Overall, TH combined with SPP could significantly inhibited MP oxidation and structural changes in surimi during frozen storage and improve the gel-forming ability, which was significantly better than single TH or SPP.

Effect of interaction between resveratrol and myofibrillar protein on the production of bound heterocyclic amines

To elucidate the pathways and mechanisms by which polyphenols inhibit protein-bound heterocyclic amines (HAs), the influence of resveratrol on bound/free HAs and the structure changes of myofibrillar proteins (MP) in the system of creatinine/MP/glucose model was studied. The results demonstrate that resveratrol significantly reduced bound and free HAs in the reaction systems (P < 0.05), and facilitates the transition from bound to free HAs. In addition, resveratrol altered the secondary structure of MP and had a static quenching effect on MP fluorescence. The strong interactions between resveratrol and MP are mainly hydrogen bonding and hydrophobic interactions. Furthermore, the results of molecular docking demonstrated that resveratrol exposed more hydrophobic amino acids (Ala, Lys and Pro) at the 556–578 amino acid sites of myosin. These results indicate that resveratrol controls the formation of bound HAs by reducing exposure to amino acids involved in the HAs reaction and promoting exposure to non-precursor amino acids.

Oxidation affects pH buffering capacity of myofibrillar proteins via modification of histidine residue and structure of myofibrillar proteins

The pH buffering capacity is an important functionality of muscle proteins, and muscle foods are susceptible to being oxidized during storage and processing. In order to study the effect of oxidation on the pH buffering capacity of myofibrillar proteins, myofibrils extracted from snakehead fish (Channa argus) were oxidized with H2O2. Results showed that increased oxidation led to loss of free sulfhydryl groups, formation of carbonyl groups, increased surface hydrophobicity, and aggregation of myofibrillar proteins. In addition, there was a significant reduction in the content of histidine in oxidized myofibrillar proteins. The pH buffering capacity of myofibrillar proteins significantly decreased from 3.14 ± 0.03 mM H+/(mL × ΔpH) down to 2.55 ± 0.03 mM H+/(mL × ΔpH) after oxidation with 50 mM H2O2. Both oxidized myofibrillar proteins and histidine showed a high pH buffering capacity at pH near 5.8, which is the histidine pKa value. Here, we hypothesize that oxidation-induced changes in the pH buffering capacity of myofibrillar proteins were driven by oxidative modification of histidine and structural changes of myofibrillar proteins. The significance of this study to food industry may be the awareness that protein oxidation may affect pH through changes in buffering capacity. And the use of antioxidants, especially those targeting at histidine will be promising in addressing this issue.

Dual cryoprotective and antioxidant effects of young apple polyphenols on myofibrillar protein degradation and gelation properties of bighead carp mince during frozen storage.

Commercial cryoprotectants can delay quality loss in frozen fish mince, but they are associated with a sweet taste and high calorie content. Young apple polyphenols (YAP), extracted from unripe apples, show potential as an alternative cryoprotectant. This study evaluated the cryoprotective effect of YAP at varying levels (0.3%, 0.7%, and 1%) in unwashed bighead carp mince. The changes in sulfhydryl content, carbonyl content, thiobarbituric acid reactive substances, intrinsic fluorescence intensity, and Fourier transform infrared spectrum indicated that YAP retarded oxidation and structural changes in myofibrillar proteins during the first 8 weeks of frozen storage, as well as lipid oxidation, which protected the structure of myofibrillar protein. At higher concentrations (0.7% and 1%), YAP maintained gel properties, gel springiness, and water-holding capacity of the gel prepared from frozen fish mince, potentially through the promotion of cross-linking of myofibrillar proteins. Overall, YAP can be used as a cryoprotectant and antioxidant in fish mince. PRACTICAL APPLICATION: Our research found that young apple polyphenols have the potential to be an alternative to commercial cryoprotectants. Young apple polyphenols may be used as a sugar-free and healthy cryoprotectant for frozen fish mince production in the future.

Myofibril degradation and structural changes in myofibrillar proteins of porcine longissimus muscles during frozen storage

The effect of frozen time and the temperature on myofibril degradation and the structure of myofibrillar proteins of porcine longissimus muscles were investigated. With extended frozen time and increased temperature, the muscle fibres became broken; the muscle cells became irregularly arranged; and the fragmentation index value, number of ionic bonds, and number of hydrogen bonds of the samples significantly decreased. Meanwhile, the myofibril fragmentation index value, number of hydrophobic interactions, and number of disulphide bonds significantly increased (P < 0.05). After 12 months of storage, the intensities of I760/I1003, I850/I830, I1450/I1003, and I2945/I1003 in the samples frozen at −8 °C were reduced by 4.36 %, 1.28 %, 1.86 %, and 0.74 %, respectively. A reduction in the maximum absorption peak and a red shift were observed in the ultraviolet spectrum. Therefore, frozen storage resulted in significant damage to the tissue microstructureand caused accelerated protein degradation, and the loss of protein structural integrity.

Characterization and the mechanism underlying the cryoprotective activity of a peptide from large yellow croaker (Pseudosciaena crocea)

Ice crystal-induced protein denaturation is the main cause of the deterioration of fish during frozen storage and transportation. In this study, the ultra-performance liquid chromatography − quadrupole − time of flight (UPLC-Q-TOF) technique was used to identify and screen tryptic peptides Ile-Glu-Glu-Leu-Glu-Glu-Leu-Glu-Ala-Glu-Arg (IEELEEELEAER) from large yellow croaker (Pseudosciaena crocea). The results were used study their cryoprotective effects on turbot fish meat during freeze–thaw cycles at different concentrations, and to investigate their anti-freezing mechanism. The results showed that the I-2.0 group effectively inhibiting the degeneration and structure changes of myofibrillar proteins after three freeze–thaw cycles, and the Ca2+-ATPase activity (1.65 μmolPi/mg/h), increased by 55.86% compared with that of the control group. Additionally, peptide IEELEEELEAER could provide antifreeze protection by binding to the surface of ice crystals and inhibiting their transformation. This peptide acts as a natural cryoprotectant and might be used for the cryogenic storage and transportation of fish products.

Microbial transglutaminase promotes cross-linking for enhancing gelation of myofibrillar protein in frozen Litopenaeus vannamei through deamination reaction

In this paper, the effects of different microbial transglutaminase (mTGase) treatments (0–0.5% w/w) on the structural and functional characteristics of frozen shrimp (Litopenaeus vannamei) were investigated to explore the changes in myofibrillar protein (MP) during the catalytic process of mTGase, and further enhance the gel properties of shrimp surimi products. Fourier transform infrared spectroscopy showed that mTGase treatment caused a shift from α-helix to β-turn and β-sheet in the secondary structure of the protein, while chemical force results indicated that moderate addition of enzyme could promote the formation of disulfide bonds in the gel system, contributing to the formation of a stable three-dimensional spatial structure. These structural changes led to a significant increase in gel strength, WHC and storage modulus (G′) after mTGase-induced protein gelation, resulting in an increase in the solid properties of the gel; and the relaxation time T22 was significantly shortened, indicating a gradual decrease in water freedom in the protein gel network. In addition, scanning electron microscopy results showed that the gel with 0.4% mTGase had a denser network structure and more uniform pores. Simultaneously, mTGase facilitated the reduction of free amino groups through deamination reaction, resulting in an elevated cross-linking degree and a reduced hydrolysis rate of pepsin. The above results indicated that appropriate mTGase treatment could improve the structure and functional properties of shrimp, benefit the quality of shrimp surimi products, and provide some references for the highly processed frozen Litopenaeus vannamei.

Gelation characteristics of partially purified myofibrillar proteins extracted from commercially harvested Indian mackerel and threadfin bream.

Gelling behaviors of partially purified myofibrillar proteins (PPMP) extracted from Indian mackerel (IM) and threadfin bream (TB) as a function of heating temperatures (20-75°C) were comparatively studied. PPMP obtained from IM (IM-MP) showed lower turbidity and surface hydrophobicity as compared to those extracted from TB (TB-MP). Moreover, lower disulfide bond content was noticed in IM-MP (7.7-9.46mol/106 g protein) as compared to TB-MP (10.99-13.95mol/106 g protein) during the heating process. There was no major difference in the amino acid profile noticed between PPMP from both the species, except lysine and glutamine contents, which were higher in TB-MP. Structural analysis, FTIR spectra, amide I band, and fluorescence intensity substantiated those changes. The protein pattern also revealed autolysis of IM-MP. The transmission analysis also showed lower aggregation and crosslinking ability of IM-MP than TB-MP. Therefore, poorer gelling behavior of IM-MP reconfirmed the inferior gel property of surimi gel from IM to gel from TB. Potential development is still required for the improvement of the gel properties of dark-fleshed fish surimi such as IM. PRACTICAL APPLICATION: Indian mackerel (IM) is an abundant and widely captured fish species. Due to overexploitation of lean fish, pelagic fish could be explored as a potential raw material for surimi production. However, poor gelling properties of IM limit its use in the surimi industry. This study provides an insight into the gelling behavior of myofibrillar proteins from IM during the gelation process in comparison with the lean fish (threadfin bream). Overall, structural and rheological changes of myofibrillar proteins play a role in gelation, thus affecting gel properties between two species. Further improvement of the gel of IM is still required.

Changes in glycated myofibrillar proteins conformation on the formation of Nε-carboxymethyllysine under gradient thermal conditions.

Nε-carboxymethyllysine (CML), a frequently used marker of advanced glycation end products (AGEs) in food, was generated in food processing easily and caused changes in myofibrillar proteins (MPs) characterization. The relevance between glycosylated MPs structure alternation and CML formation under thermal conditions have been reported. However, the correlation mechanism was not clear yet. In this work, the influence of gradient heating (50℃, 60℃, 70℃, 80℃, and 90℃) on the different degrees of glycated MPs, which determined the correlation with CML formation in protein structural changes of MPs. In the rising stage of the CML level, glycation accelerated the fibrillation and aggregation behavior of MPs during heating and increased surface hydrophobicity and particle size. The protein cross-linking affected the protein modification caused by heating and glycation. This work highlights the substantial influences of glycosylation and thermal treatments on MPs, which transformed the MPs structural characteristics and CML level.

Formation mechanism of texture characteristics of pork belly during stewing: focusing on the effects of myofibrillar protein modification

SummaryThe effects of stewing at a constant temperature (95 °C) for different times (45 and 90 min) on the physicochemical characteristics of lean meat (LM) and lean meat in pork belly (LMIPB) were investigated. When the stewing time was 90 min, the hardness, springiness, cohesiveness and chewiness of LMIPB were 186.35 g, 0.07 (ratio), 0.18 (ratio) and 241.90 g lower than those of LM, respectively. The chemical changes in myofibrillar protein (MP) mainly including the degree of oxidation degradation, such as carbonyl content, cross‐linked polymer and β‐sheet, were increased with prolonged stewing time. The sulfhydryl content, Zeta potential (absolute value) and α‐helix were decreased markedly. The chemical changes of MP in the LMIPB were greater than those in the LM during the stewing process. These results indicated that fat in stewing process could promote the oxidation degradation of MP in meat, and then affected the texture characteristics of meat.

Proteomics in bovine semitendinosus muscle to assess emerging strategies based on papain injection and ultrasounds on meat tenderization process

The impact of papain and/or ultrasound treatments on tenderization of semitendinosus muscle through a proteomic approach was studied. Sixteen bovine muscles were submitted to the following treatments: aging at 3 °C (Control), papain injection (PI), ultrasound (US), PI followed by US (PIUS) and US followed by PI (USPI). pH, myofibrillar fragmentation indices (MFI), soluble collagen, texture profile and changes of myofibrillar proteins were investigated after 2, 24, 48 and 96 h of storage. The highest MFI and soluble collagen content were found in PI, PIUS and USPI samples while control samples showed the lowest values. PI samples showed the lowest WBSF and hardness values until 48 h of storage while at 96 h meat from USPI treatment showed WBSF value comparable to PI treatment. The lowest values of cohesiveness, gumminess and chewiness were found in PI samples during all storage times.Proteomic analysis revealed a different quantity and expression of proteins among tenderization treatments. US treatment did not exhibit a significant ability to degrade muscle proteins, while, all treatments containing papain, showed a greater ability to hydrolyse and degrade myofibrillar proteins. PI promoted intense proteolysis leading to an early tenderization process; on the contrary, in PIUS and USPI treatments the sequence of treatments was relevant on meat tenderization. Particularly, USPI treatment, after 96 h, reached the same improvement in tenderness of enzymatic treatment but with slower hydrolysing rate; this could be determinant to preserve textural structure.

Mechanisms of chicken processing quality changes during the early postmortem time: the role of the changes in myofibrillar protein

SummaryThe properties of white meat, such as chicken and fish, changed quickly in the early postmortem period. This study focused on the relationship between myofibrillar protein and the eating quality of chicken in this period. The results showed that the eating quality of chicken, such as texture, water holding capacity and shear force value, decreased in the early postmortem period. The western blot analysis indicated that the desmin and troponin T were degraded significantly with postmortem time. Meanwhile, the myofibril protein degeneration in this period was evaluated by Fourier transform infrared and Differential Scanning Calorimetry. The findings demonstrated that the ordered structure of the myofibrillar protein was destroyed, and its thermal stability was reduced with the prolongation of postmortem time. Subsequently, the transmission electron microscope results suggested that the heating processing could destroy the connection between the weakened Z‐line and the myofilament. Overall, the decline in thermal stability and degradation of myofibrillar may worsen the structural instability of chicken during heating, which may be a significant contributor to the variations of chicken quality in the early postmortem period.

Cryoprotective effect of collagen hydrolysates from squid skin on frozen shrimp and characterizations of its antifreeze peptides

The cryoprotective effect of collagen hydrolysates from squid skin (CH-SS) on shrimp muscle was investigated during the freeze-thaw cycles, and the antifreeze peptides (AFPs) in CH-SS were separated and identified. The results showed that CH-SS generated by acid protease had the highest antifreeze activity. It was further found that CH-SS showed an inhibitory effect on the denaturation and structural changes of myofibrillar protein during the freeze-thaw cycles, and partially retained the ability to bind water. SEM analysis indicated that CH-SS could effectively reduce the mechanical injury caused by ice crystals to shrimp muscle. The fraction with the highest antifreeze activity from CH-SS was obtained by Sephadex G-25 chromatography, and its main amino acid sequence was identified as DVRGAEGSAGL by the UPLC-MS analysis. This study provides a theoretical basis for the intensive processing of squid skin and the development of new antifreeze agents.

Analysis of inhibition of guava (Psidium guajava l.) leaf polyphenol on the protein oxidative aggregation of frozen chicken meatballs based on structural changes

This study compared the effects of guava leaf polyphenol (GLP) on the aggregation and structural changes of myofibrillar proteins (MPs) from chicken meatballs, frozen for 6 months, with that of tea polyphenol (TP). The high antioxidation ability of 450 mg/L GLP was manifested by changes in 1, 1-diphenyl-2-picrylhydrazyl (DDPH), 2, 2-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging activity, and the ferric reducing antioxidant power (FRAP) in vitro. Compared with the control, the carbonyl, disulfide bond content, particle size, zeta potential and turbidity of sample with GLP decreased by 25.9 %, 17.7 %, 18.2 %, 11.4 % and 11.7 %, respectively, while the solubility of the sample, after freezing it for 6 months, increased by 14.8 %. Meanwhile, in sustaining the structural stability of MPs, the GLP-treated group exhibited better microstructure (scanning electron microscopy, SEM), lower free amino and sulfhydryl loss, higher α-helix structure and fluorescence intensity than the control. Our results showed that GLP significantly inhibited MP aggregation, and was superior to TP in terms of its particle size, solubility, and turbidity, sulfhydryl content (P < 0.05). Overall, it was demonstrated that GLP has the potential to inhibit protein aggregation and enhance structural stability during frozen storage.

Investigation on the quality regulating mechanism of antifreeze peptides on frozen surimi: From macro to micro

Freeze denaturation of protein caused by ice crystals is the main motivation for the quality deterioration of surimi during circulation and storage. This investigation aimed to cryoprotect surimi by adding antifreeze peptides from Takifugu obscurus skin (TsAFP) which can inhibit ice recrystallization, and to elucidate regulating mechanism. The comprehensive results showed that 4% TsAFP, half dosage of commercial cryoprotectant, had good cryoprotection on surimi by reducing the moisture variation and maintaining protein solubility of surimi at macro level, as well as inhibiting the degeneration and structure changes of myofibrillar proteins at micro level. Meanwhile, TsAFP could directly bind to the structural cavity of myosin, inhibit protein freezing-induced oxidation, maintain the spatial structure of myosin and water retention ability to preserve the surimi quality. This study helped better comprehend the protective mechanisms of antifreeze peptides in frozen surimi and was expected to provide a promising cryoprotectant for low-sweetness and low-calorie surimi.

Physicochemical and Functional Properties Changes in Myofibrillar Protein Extracted from Channel Catfish by a High-Voltage Electrostatic Field

Physicochemical and Functional Properties Changes in Myofibrillar Protein Extracted from Channel Catfish by a High-Voltage Electrostatic Field

Inhibitive effect of cryoprotectants on the oxidative and structural changes in myofibrillar proteins of unwashed mince from silver carp during frozen storage

Silver carp is a type of Asian carp that poses a threat to the United States. Unfortunately, producing Asian carp surimi in the US has been unsuccessful due to the high cost. Thus, exporting Asian carp to China and other Asian countries in the form of frozen deboned fish mince (without washing) would be a new way to create commercial value. This study was to explore the effects of compound cryoprotectants CC (sucrose, sorbitol, and sodium tripolyphosphate) and CC + SD (salted egg white) on unwashed silver carp mince during frozen storage. In the presence of CC, unwashed mince exerted benefits on gel property and water holding property. CC was able to retard protein oxidation as indicated by the retarded carbonyl content and lower loss in sulfhydryl content. Based on indicators of content of salt-soluble protein, α-helix, myosin heavy chain and intrinsic fluorescence intensity, CC addition inhibited protein aggregation by protecting the protein structure. The inclusion of SD did not show a cryoprotective effect or synergistic antioxidant effect with sucrose-sorbitol, but SD improved the gel strength within 4 weeks of freezing. Thus, CC can provide cryoprotective protection during frozen storage of silver carp mince. CC + SD provides a reference for long-distance transport and off-site production of frozen silver carp mince.