Myofibrillar Protein Degradation Research Articles

Insight into the evolution of textural properties and juiciness of ready-to-eat chicken breasts upon different thermal sterilization: From the perspective of protein degradation.

Texture deterioration of meat products upon high-temperature sterilization is a pressing issue in the meat industry. This study evaluated the effect of different thermal sterilization temperatures on the textural and juiciness of ready-to-eat (RTE) chicken breast. In this study, by dynamically monitoring the texture and juiciness of chicken meat products during the process of thermal sterilization, it has been observed that excessively high sterilization temperatures (above 100°C) significantly diminish the shear force, springiness and water-holding capacity of the products. Furthermore, from the perspective of myofibrillar protein degradation, molecular mechanisms have been elucidated, unveiling that the thermal sterilization treatment at 121°C/10 min triggers the degradation of myosin heavy chains and F-actin, disrupting the lattice arrangement of myofilaments, compromising the integrity of sarcomeres, and resulting in an increase of approximately 40.66% in the myofibrillar fragmentation index, thus diminishing the quality characteristics of the products. This study unravels the underlying mechanisms governing the dynamic changes in quality of chicken meat products during the process of thermal sterilization, thereby providing theoretical guidance for the development of high-quality chicken products.

Assessment of Pyracantha fortuneana fruit extract as a nitrite substitute on the physicochemical properties, sensorial profile, safety risks and functional properties of fermented beef sausages

This study aimed to investigate the effect of Pyracantha fortuneana fruit extract (PFE) as a nitrite substitute on the quality, flavor, contents of biogenic amines and the formation of antioxidant peptides of fermented beef sausages during storage. Compared with the control group, the fermented beef sausages treated with PFE showed elevated L* and a × values, enhanced antioxidant activity, and increased resistance to microbial growth and lipid and protein oxidation. In particular, there were 2.44 ± 0.02 mg MDA/kg thiobarbituric acid reactive substances after 35 d. Interestingly, PFE had a positive effect on the texture, flavor, and antioxidant protection of fermented beef sausages that was superior to that of nitrite. PFE not only improved the microstructure of fermented beef sausage but also delayed the degradation of myofibrillar and sarcoplasmic proteins as shown in SDS-PAGE analysis, which resulted in a significant improvement in the sausage flavor and reduction of biogenic amines (P < 0.05). The LC-MS/MS results showed that PFE-treated fermented sausages significantly promoted peptide formation and had high 2,2-diphenyl-1-picrylhydrazyl radical scavenging and ferric ion reducing antioxidant power (P < 0.05). Therefore, PFE has the potential to be effective and promising substitute for nitrite in industrial production and application in fermented sausages.

Exploring the impact of malondialdehyde and 4-hydroxy-2-nonena on myofibrillar protein structure: A proteomic analysis

In this investigation, the impacts of malondialdehyde (MDA), 4-hydroxy-2-nonena (HNE), and their combinations on the structural characteristics of myofibrillar proteins (MP) were examined using endogenous fluorescence, Fourier transform infrared spectrum (FTIR) and Sodium Dodecyl Sulfate Polyacrylamide Gel Electrophoresis (SDS-PAGE). The potential binding mechanisms were also explored using LC-MS/MS and proteomics techniques. The findings indicated that various reactive carbonyl compounds (RCCs) displayed distinct oxidation performances in the oxidation of myofibrillar proteins. Samples containing HNE (HMP and MHMP groups) exhibited a more pronounced ability to oxidize MP than those containing MDA, as evidenced by their higher carbonyl content and lower sulfhydryl content. The MHMP group demonstrated the greatest surface hydrophobicity and Schiff base content but the lowest fluorescence intensity, suggesting that MDA and HNE synergistically altered MP conformation. Moreover, the alteration by RCCs notably modified the secondary structure of MP. Among these, HMP triggered the unfolding of MP molecules, resulting in the lowest α-helix and highest β-sheet ratio. The SDS‒PAGE results suggested that MDA oxidation promoted the crosslinking of MP molecules. At the same time, HNE caused the degradation of MP, as indicated by the decrease in the intensity of the high-molecular-weight bands. Proteomic analysis suggested that lysine residues distributed in the tail region of myosin were the main binding sites for MDA, whereas HNE preferentially modified methionine located at the myosin head. Additionally, HNE-induced protein degradation dominated RCC-induced oxidation reactions. These findings provide deeper insights into the mechanisms underlying quality changes induced by lipid oxidation products in MP-based food systems.

Inoculation fermentation with Lactobacillus fermentum L28 and Staphylococcus epidermidis S24 for improving the protein degradation of air-dried goose

The inoculation fermentation technology was applied to the processing of dried cured goose to investigate the protein degradation. Lactobacillus fermentum (L), Staphylococcus epidermidis (S) and mixed strains (L + S) were individually inoculated into the whole goose before drying. We studied the degradation of protein in the air-dried period of goose. The results showed that compared with natural fermentation, inoculation fermentation significantly increased the content of non-protein nitrogen (14.85 mg/g NPN), proteolysis index (8.98% PI), myofibril fragmentation index (89.35 MFI) and total amount of free amino acids (1332.6 mg/g FAA) of dried cured goose. Electrophoresis revealed that the inoculation fermentation accelerated the degradation of macromolecular proteins and the accumulation of small molecular proteins. The degree of protein degradation in four groups of goose was in an order of L + S group > S group > L group > CK group. It suggested that inoculation fermentation could promote the degradation of myofibrillar proteins.

Effect of ultrasound combined with pineapple protease treatment on the tenderness of dried shrimp.

In order to improve the tenderness of dried shrimp products as well as to reduce the hardness of the meat during the drying process, shrimp were treated with ultrasound combined with pineapple protease and the tenderization condition was optimized by measuring the texture and shear force of dried shrimp. In addition, the sulfhydryl content, myofibril fragmentation index (MFI) and microstructure were also examined to clarify the mechanisms of shrimp tenderization. The results showed UB1 group withultrasonic power of 100 W, heating temperature of 50 °C and pineapple protease concentration of 20 U mL-1 were the optimum tenderization conditions, where shrimp showed the lowest hardness (490.76 g) and shear force (2006.35 gf). Microstructure as well as sodium dodecyl sulfate-polyacrylamide gel electrophoresis results suggested that during the tenderization process the muscle segments of shrimps were broken, degradation of myofibrillar proteins occurred, and MFI values and total sulfhydryl content increased significantly (P < 0.05) (MFI value = 193.6 and total sulfhydryl content = 93.93 mmol mg-1 protein for UB 1 group). Ultrasound combined with bromelain could be used as a simple and effective tenderization method for the production of tender dried shrimp. The best conditions were 100 W ultrasonic power, 50 °C ultrasonic temperature, and 20 U mL-1 bromelain. © 2024 Society of Chemical Industry.

New perspective for Calpain-Mediated regulation of meat Quality: Unveiling the impact on mitochondrial pathway apoptosis in post-mortem

While calpain's role in myofibrillar protein degradation is well-established, its impact on post-mortem apoptosis remains fully elucidated. This study aimed to examine how calpain influences the mitochondrial apoptotic pathway in post-mortem muscle cells and assess its potential impact on chicken tenderness. The findings indicate that the calpain inhibitor treatment could decelerate the rate of lysosome destruction in post-mortem chicken, which is a crucial factor in delaying the mitochondrial apoptotic pathway. Subsequently, this inhibition enhanced the mitochondrial membrane’s stability and suppressed the apoptosis-inducing factor Cyt c release into the sarcoplasm. The Western blot results in a greater myofibrillar protein degradation degree in the caspase inhibitor samples compared to the calpain inhibitor samples. Interestingly, the two groups had no significant difference in shear force. Based on these reasons, a novel perspective was introduced in this paper: Calpain could affect the change in meat tenderness by regulating mitochondrial apoptosis in the post-mortem period.

Comparative effects of phosphorylation and acetylation on glycolysis and myofibrillar proteins degradation in postmortem muscle

The study investigated the different effects between protein phosphorylation and acetylation on glycolytic enzyme activity and myofibrillar protein degradation. Lamb longissimus thoracis lumborum muscles were homogenized and then inhibitors were added for incubation at 4 °C. Phosphatase inhibitor was added to produce a high phosphorylation level (PI group) and lysine deacetylase inhibitor was added to produce a high acetylation level (DI group). The lactate and ATP content in the PI group was inhibited compared with that in the DI group (P < 0.05). Phosphofructokinase (PFK) activity was negatively related with the phosphorylation level and was positively related with the acetylation level in the DI group (P < 0.05). The degradation of troponin T and desmin of the DI group were restrained when compared to that in the PI group (P < 0.05). Compared with initial PFK and desmin, the simulation of phosphorylation and acetylation of PFK and desmin showed different electrostatic potential at the surface and a more unstable structure. The phosphorylation level of the DI group was increased, suggesting that the changes of protein acetylation altered protein phosphorylation. In conclusion, compared with protein phosphorylation, protein acetylation had a greater effect on promoting glycolysis and inhibiting protein degradation.

Aging mechanism for improving the tenderness and taste characteristics of meat.

Tenderness and taste characteristics of meat are the key determinants of the meat choices of consumers. This review summarizes the contemporary research on the molecular mechanisms by which postmortem aging of meat improves the tenderness and taste characteristics. The fundamental mechanism by which postmortem aging improves the tenderness of meat involves the operation of the calpain system due to apoptosis, resulting in proteolytic enzyme-induced degradation of cytoskeletal myofibrillar proteins. The improvement of taste characteristics by postmortem aging is mainly explained by the increase in the content of taste-related peptides, free amino acids, and nucleotides produced by increased hydrolysis activity. This review improves our understanding of the published research on tenderness and taste characteristics of meat and provides insights to improve these attributes of meat through postmortem aging.

Binding of Selected Aroma Compounds to Myofibrillar Protein, Sarcoplasmic Protein, and Collagen during Thermal Treatment: Role of Conformational Changes and Degradation of Proteins.

To investigate the effects of conformational changes and thermal degradation of myofibrillar protein (MP), sarcoplasmic protein (SP), and collagen (CO) on the binding ability for aroma compounds during heating. Using SDS-PAGE, HPLC, and LC-MS/MS, a consistent rise in the total concentration of peptides and free amino acids formed by the thermal degradation of proteins was observed. The surface hydrophobicity, total sulfhydryl content, particle size, and secondary structure content of proteins changed significantly over time. Furthermore, the aroma binding ability of proteins was determined by gas chromatography-mass spectrometry. The results revealed an increase in binding ability during 5 or 10 min of heating due to protein unfolding and the accumulation of degradation products. However, the binding ability decreased due to protein aggregation with prolonged heating. Notably, all proteins exhibited strong affinity toward (E)-2-octenal, (E,E)-2,4-decadienal, 2-methyl-3-furanthiol, and dimethyl trisulfide. The binding ability of MP and SP was similar but differed significantly from that of CO, which had lower binding ability for hexanal, (E)-2-octenal, (E,E)-2,4-decadienal, and dimethyl trisulfide compared to MP and SP.

Effect of gum tragacanth–sodium alginate coatings incorporated with epigallocatechin gallate on the quality and shelf life of large yellow croaker (Larimichthys crocea) during superchilling storage

Abstract The effect of gum tragacanth (GT) and sodium alginate (SA) active coatings incorporated with epigallocatechin gallate (EGCG; 0.16%, 0.32%, and 0.64%, respectively) on the quality of large yellow croaker fillets was evaluated during superchilling storage at –3 ˚C for 42 d. The results revealed that the GT-SA-EGCG active coatings delayed microbial spoilage by reducing the total viable counts of Pseudomonas spp. and psychrophile bacteria and retarded the degradation of the physical properties of water-holding capacity, cooking loss, color, odor and texture. GT-SA-EGCG coatings could also maintain fillet freshness by maintaining lower total volatile basic nitrogen, K value, and histidine content, inhibiting myofibrillar protein degradation during superchilling storage. These results suggested that the active coatings embedded with GT-SA-EGCG could be used as a preservative to enhance the quality of large yellow croaker and prolong the shelf life by 7–14 d during superchilling storage at –3 ˚C.

Effects of proteases on textural softening and changes in physical property of harpiosquillid mantis shrimp (Harpiosquilla raphidea) during the iced storage

SummaryRapid softening of texture is a major problem associated with quality loss and consumer rejection of harpiosquillid mantis shrimp (Harpiosquilla raphidea) (HMS). Effects of endogenous proteases in muscles and digestive tract on protein degradation and softening were investigated. Scanning electron microscopic and histological images indicated drastic destruction of muscle during iced storage. Based on autolysis, maximal activity was found at pH 8.5 and 55 °C, and serine proteases including trypsin were dominant. Cathepsin B and L + B in muscle were altered throughout storage, while trypsin remained constant in HMS meat for 1–3 days. Firmness and toughness decreased and coincided with augmented degradation of myofibrillar proteins and collagen. Trypsin from the digestive tract was contaminated into the abdomen during iced storage, therefore inducing drastic hydrolysis of muscle proteins. This phenomenon caused the undesirable pasty/mushy texture associated with the loss in firmness and toughness of meat within 3 days of storage.

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.

Protein Phosphorylation Induced by Pyruvate Kinase M2 Inhibited Myofibrillar Protein Degradation in Post-Mortem Muscle.

Myofibrillar protein degradation is primarily related to meat tenderness through protein phosphorylation regulation. Pyruvate kinase M2 (PKM2), a glycolytic rate-limiting enzyme, is also regarded as a protein kinase to catalyze phosphorylation. The objective of this study was to investigate the relationship between myofibrillar protein degradation and phosphorylation induced by PKM2. Myofibrillar proteins were incubated with PKM2 at 4, 25, and 37 °C. The global phosphorylation level of myofibrillar proteins in the PKM2 group was significantly increased, but it was sensitive to temperature (P < 0.05). Compared with 4 and 25 °C, PKM2 significantly increased the myofibrillar protein phosphorylation level from 0.5 to 6 h at 37 °C (P < 0.05). In addition, the degradation of desmin and actin was inhibited after they were phosphorylated by PKM2 when incubated at 37 °C. These results demonstrate that phosphorylation of myofibrillar proteins catalyzed by PKM2 inhibited protein degradation and provided a possible pathway for meat tenderization through glycolytic enzyme regulation.

Investigating the migration hypothesis: Effects of trypsin-like protease on the quality of muscle proteins of red shrimp (Solenocera crassicornis) during cold storage

This study aimed to investigate the effect of trypsin-like protease (TLP) on the quality of muscle proteins in red shrimp (Solenocera crassicornis) during cold storage. The results indicated that the activity of TLP decreased significantly in the head of shrimp but increased significantly in the muscle tissues during the cold storage. The myofibril fragmentation index (MFI) value of intact shrimp was significantly higher than that of beheaded shrimp, while the Ca2+-ATPase activity of intact shrimp was significantly lower than that of beheaded shrimp. SDS-PAGE analysis showed that the molecular weight of purified TLP from the shrimp head was about 24 kDa, and the TLP showed high activity at 50 °C and pH 8, indicating that the TLP belongs to the trypsin family. Results from in vitro simulation experiments indicated that the process of TLP incubation significantly reduced the particle size and enlarged the distribution of myofibrillar proteins (MPs) in shrimp muscle tissues. The comparisons were made with respect to the control samples. It can be inferred that TLP migrated from the shrimp head to the muscle tissues during storage and thus promoted the degradation of MPs in red shrimp. The beheading treatment could be an effective mean to maintain better quality and extend the commercialization of shrimp products.

Evidence of myofibrillar protein oxidation and degradation induced by exudates during the thawing process of bighead carp fillets

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.

Complex organic acids treatment on crayfish (Procambarus clarkii): the relationship between myofibrillar protein structure and meat quality

SummaryThe effect of complex organic acids (COA) treatment at different concentrations (0%, 1%, 5%, 10% and 15%) on the myofibrillar protein (MP) structure and meat quality of crayfish (Procambarus clarkii) was investigated. The results showed that with increasing concentrations of COA treatment, the sulfhydryl content of MP decreased and dityrosine content increased. The MP secondary structure has a reduced α‐helix content and an increased β‐fold content. The MP tertiary structure unfolded, exposing hydrophobic and other amino acids to a polar environment. MP aggregation was induced in the 1% and 5% COA treatment groups and MP degradation was induced in the 10% and 15% COA treatment groups. Crayfish meat in the 5% COA treatment group showed improved textural properties due to protein aggregation. It also enhanced the colour, aroma and micromorphology of the crayfish meat.

Impacts of long-time transportation on whiteleg shrimp (Penaeus vannamei) muscle quality and underlying biochemical mechanisms.

Shrimp is widely consumed around the world. Since muscle is the primary edible component of shrimp, muscle quality (particularly texture) has a direct impact on the economic value of shrimp products. However, reports on the shrimp muscle quality influenced by transportation are rather limited, and the underlying mechanism remains unknown. During the simulated transportation, the water pH and total ammonia-nitrogen content and un-ionized ammonia contents were elevated. Furthermore, reductions in shrimp muscle water-holding capacity, hardness, and shear value with intensive myofibrillar protein degradation were detected. Simulated transportation decreased the pH and glycogen content of shrimp muscle while increasing lactic dehydrogenase activity and lactate content, resulting in an elevated level of free calcium ions and increased μ-calpain and general proteolytic activities. Water exchange could improve the water quality and reduce the mortality of shrimp during transportation, as well as decrease muscle textural softening by alleviating these stress responses. Maintaining water quality and, in particular, reducing ammonia are critical to improving shrimp survival and muscle quality during live transportation. This study is of great significance for the better maintenance of the textural properties of shrimp meat. © 2023 Society of Chemical Industry.

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.

Oxidation of Cathepsin D by Hydroxy Radical: Its Effect on Enzyme Structure and Activity against Myofibrillar Proteins Extracted from Coregonus peled.

In this study, cathepsin D was oxidized in vitro with different concentrations of H2O2, and the activity, structure, and extent of myofibrillar protein degradation by oxidized cathepsin D were evaluated. The sulfhydryl content of cathepsin D decreased to 9.20% after oxidation, while the carbonyl content increased to 100.06%. The β-sheet in the secondary structure altered due to oxidation as well. The changes in the intrinsic fluorescence and UV absorption spectra indicated that oxidation could cause swelling and aggregation of cathepsin D molecules. The structure of cathepsin D could change its activity, and the activity was highest under 1 mM H2O2. Cathepsin D could degrade myofibrillar proteins in different treatment groups, and the degree of degradation is various. Therefore, this study could provide a scientific basis for the mechanism of interaction among hydroxyl radical oxidation, cathepsin D, and MP degradation.

Physicochemical properties, microstructure and protein characteristic of frozen chicken feet as affected by different thawing methods

ABSTRACT In this study, the effects of six thawing methods (flowing water thawing, FWT; water immersion thawing, WIT; room temperature air thawing, RTAT; low temperature air thawing, LTAT; ultrasonic-assisted thawing, UAT; and microwave thawing, MT) on water holding capacity (WHC), shear force, tissue microstructure, thiobaric acid active substances (TBARS), myofibrillar fragmentation index (MFI), protein secondary structure and myofibrillar protein (MP) oxidation of frozen chicken feet were investigated. The results demonstrated that UAT improved the sample tenderness with a minimum shear force of 775.67 ± 63.30 g. The WHC of the UAT sample also presented a high level; the thawing and cooking losses reached 4.20 ± 0.33% and 3.23 ± 0.35%, respectively. Although the LTAT sample presented a lower loss in the thaw (2.72 ± 0.23%) and a high α-helix content (30.54 ± 1.69%), it showed a significantly higher TBARS value (0.62 mg MDA/kg) (P < .05). On the other hand, it was observed a significant inhibition of fat oxidation in the FWT sample (0.19 ± 0.01 mg MDA/kg) (P < .05). However, the SDS-PAGE diagram showed that the MPs in this sample exhibited a significant degradation. Furthermore, the MT process could lead to partial overcooking of the chicken feet, resulting in poor physicochemical properties. Overall, the results indicate that the UAT method could be the most recommended process to thaw chicken feet, providing optimal tenderness with more intact microstructure and less MP degradation. This study provides relevant evidence, for consumers and industrial practice, regarding thawing methods that can be applied to frozen chicken feet