Cross-linked Myosin Heavy Chain Research Articles

Physicochemical properties and gel-forming ability changes of duck myofibrillar protein induced by hydroxyl radical oxidizing systems.

This paper focuses on the changes of physicochemical properties and gel-forming ability of duck myofibrillar proteins (DMPs) induced using hydroxyl radical oxidizing systems. DMPs were firstly extracted and then oxidized at various H2O2 concentrations (0, 4, 8, and 12 mmol/L) using Fenton reagent (Fe3+-Vc-H2O2) to generate hydroxyl radicals, and the effects of hydroxyl radical oxidation on the physicochemical changes and heat-induced gel-forming capacity of DMPs were analyzed. We observed obvious increases in the carbonyl content (p < 0.05) and surface hydrophobicity of DMPs with increasing of H2O2 concentrations (0-12 mmol/L). In contrast, the free thiol content (p < 0.05) and water retention ability of DMPs decreased with increasing H2O2 concentrations (0-12 mmol/L). These physicochemical changes suggested that high concentrations of hydroxyl radicals significantly altered the biochemical structure of DMPs, which was not conducive to the formation of a gel mesh structure. Furthermore, the gel properties were reduced based on the significant decrease in the water holding capacity (p < 0.05) and increased transformation of immobilized water of the heat-induced gel to free water (p < 0.05). With the increase of H2O2 concentrations, secondary structure of proteins analysis results indicated α-helix content decreased significantly (p < 0.05), however, random coil content increased (p < 0.05). And more cross-linked myosin heavy chains were detected at higher H2O2 concentrations groups through immunoblot analysis (p < 0.05). Therefore, as H2O2 concentrations increased, the gel mesh structure became loose and porous, and the storage modulus and loss modulus values also decreased during heating. These results demonstrated that excessive oxidation led to explicit cross-linking of DMPs, which negatively affected the gel-forming ability of DMPs. Hence, when processing duck meat products, the oxidation level of meat gel products should be controlled, or suitable antioxidants should be added.

Effect of nano eggshell calcium on the structure, physicochemical, and gel properties of threadfin bream (Nemipterus virgatus) actomyosin

In order to explore the mechanism of nano eggshell calcium (NEC) enhancing the gel properties of surimi. The effects of NEC on the structure, physicochemical, and gel properties of myosin were investigated. The results revealed that the addition of NEC improved gel strength, storage modulus G′, and surface hydrophobicity of myosin. The maximum value was reached when the addition was 1.0 g/100 g. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the addition of NEC has a significant effect on the cross-linking of myosin heavy chain (MHC). FT-IR and fluorescence spectroscopy analysis indicated that NEC could induce the unfolding of myosin and promoted the conformational transition from α-helix to β-sheet. Scanning electron microscopy (SEM) observed that adding a moderate content of NEC (≤1.0 g/100 g) was conducive to the formation of homogeneous and dense three-dimensional network structure of myosin mixed gel. However, the addition of excessive NEC (≥1.25 g/100 g) weakened its structural properties. These results of the present study suggested that NEC has potential to be applied in surimi seafood products, and has potential applications in improving the gel structure and gel properties.

Understanding the role of atmospheric cold plasma (ACP) in maintaining the quality of hairtail (Trichiurus Lepturus)

Impacts of atmospheric cold plasma (ACP) on the properties of muscle protein and performance of extracted crude enzyme of hairtail (Trichiurus Lepturus) fish have been evaluated. A decrease in extracted crude enzyme activity with increasing the ACP treatment time has been found, and the highest reduction (p < 0.05) value of 0.035 units/mg proteins was obtained after 240 s. A considerable increase in the carbonyl content in the treated sample for about three times higher than the control sample was found, and a decrease of total sulfhydryl content to 0.34 nmol/mg protein. Texture profile analysis, water holding capacity, and the color properties of the muscle protein improved significantly in the samples treated with ACP. SDS-PAGE pattern showed an increase in the band intensity of cross-linked myosin heavy chains and actin proteins. Based on these outcomes, ACP could play a significant role as a promising non-thermal method to prolong the shelf-life of hairtail fish.

Combination of light and oxygen accelerates formation of covalent protein-polyphenol bonding during chill storage of meat added 4-methyl catechol

Plant polyphenols applied as natural antioxidant ingredients, are known to bind to cysteine residues on meat proteins. The aim of this study was to examine the effect of light exposure on the formation of cysteine-phenol adduct in meat added 4-methylcatechol (4MC), a model polyphenol, during storage through quantitative LC-MS/MS-based analysis. Cysteine-4-methylcatechol adduct (Cys-4MC) formation in meat added 1500 ppm 4-MC increased significantly (by 50%) when stored under light in oxygen at 4 °C for 7 days as compared to storage in the dark. This was reflected by a significant decrease in thiol concentrations in the same sample. Gel electrophoresis showed loss in myosin heavy chain (MHC), and a resulting increase in cross-linked MHC (CL-MHC) and larger protein polymers in samples added 4MC. Protein blots stained with nitroblue tetrazolium (NBT) showed intensive protein-polyphenol binding in the meat samples added 4MC, but no major differences between storage conditions.

Effects of gamma ray irradiation-induced protein hydrolysis and oxidation on tenderness change of fresh pork during storage

This study investigated the effect of irradiation (0, 3, 5 or 7 kGy) on the tenderness changes of pork during storage at 4 °C for two weeks by determining the total carbonyl, sulfhydryl groups, peptidomic profiles, Warner-Bratzler (WB) shear force value and by gel electrophoresis (SDS-PAGE) experiment. The results showed that, irradiation significantly increased total carbonyl content of pork but had no significant effect on sulfhydryl groups. Protein thiol loss induced by irradiation was greatly promoted after storage for 3 days. Increasing irradiation dose level could significantly decrease the WB shear force value of samples (P < .05) by provoking degradation of myofibrillar protein and collagen fragments. During refrigerated conditioning, however, the WB shear force values increased significantly despite irradiation (P < .05). This was attributed to increasing amount of collagen solubilized from muscle, protein aggregation induced by carbonylation of troponin T (at 7 days of storage) and further cross-linking of myosin heavy chain (MHC) (at 14 days of storage).

Effects of iron-catalyzed and metmyoglobin oxidizing systems on biochemical properties of yak muscle myofibrillar protein

The objective of this study was to compare the effects of two oxidation systems on the biochemical properties of yak myofibrillar protein (MP). Oxidation was induced by incubating MP with either an iron-catalyzed oxidizing system (IOS) or a metmyoglobin-oxidizing system (MOS). The following indicators of protein oxidation and protein degradation were analyzed. The carbonyl, disulfide bonds, dityrosine, and β-sheet content increased markedly with oxidant concentration in both systems(P < .05), whereas the total sulfhydryl, surface hydrophobicity and α-helix content decreased significantly(P < .05). Furthermore, the MOS carbonyl formation rate was significantly faster than the IOS rate, and the MOS significantly affected the formation of disulfide bonds and inhibited the exposure of hydrophobic amino acids. Both oxidative systems promoted cross-linking of myosin heavy chains (MHCs) and action, but the degree of cross-linking in IOS was greater than that in MOS. MOS also promoted cross-linking of myosin light chains (MLCs). IOS and MOS produced mainly 20–25-kDa and 20–17-kDa MLC degradation products, respectively. In conclusion, oxidation caused cross-linking in MHCs or MLCs through disulfide bonds, but the extent of such cross-linking was oxidant dose-dependent and specific to each oxidizing system.

Gelling properties of vacuum-freeze dried surimi powder as influenced by heating method and microbial transglutaminase

Effects of heating method and addition of microbial transglutaminase (MTGase) on properties of gels made from vacuum-freeze dried silver carp surimi were investigated. After vacuum-freeze drying, surface hydrophobicity of surimi proteins obviously increased, Ca2+-ATPase activity slightly decreased, while α-helix percentage significantly decreased, indicating the surimi proteins were partially denaturated. Consequently, the dried surimi formed gels (D gel) with significantly lower breaking force, penetration distance and water holding capacity as compared with those of gels made from frozen surimi (F gel) under all the heating methods. With addition of MTGase, breaking force of the D gels heated at 40 °C/60 min and 90 °C/30 min was not significantly different from those of F gels, while was slightly lower under the heating of 40 °C/60 min + 90 °C/30 min. After adding MTGase, water holding capacity of the D gel under 90 °C heating increased significantly, while the gels under the other heating methods slightly deceased. Heating method obviously influenced color parameters of D gels while MTGase addition did not. Setting (40 °C) and MTGase addition induced covalent cross-linking of myosin heavy chains of D gels. MTGase addition reduced the uniformity of the water distribution in D gels.

Effects of Oxidative Cross-Linking of its Myofibrillar Protein on Texture during the Processing of Air-Dried Yak Meat

ObjectivesThis study aimed to examine the mechanism of cross-linking of myofibrillar protein and its influence on texture during the processing of air-dried yak meat.Materials and MethodsThe semimembranosus of 9 healthy and disease-free male yaks when they were 3 to 4-yr-old under natural grazing was selected for 20 kg, and these yaks are all from Gannan Prefecture, Gansu Province, China. The fascia and fat on the surface of the raw meat were removed and cut into strips with a cross-section of 2 cm × 2 cm in a freeze-dried room away from direct sunlight and naturally ventilated (room temperature –10 ∼ –15°C, relative humidity 50 ∼ 75%). The meat was hung on the wire, and the distance between adjacent 2 meats was maintained at 1 to 2 cm. Samples were collected during natural air-drying for 60 d. Carbonyl content, total thiol concentration, disulfide bond content, SDS-PAGE, dimeric tyrosine content, the surface hydrophobicity, histological characteristics and texture were measured, respectively. All of the experiments were conducted in triplicate for each sample, and the final results from the mean of 3 independent experimental replications. Dimeric tyrosine content, the surface hydrophobicity, histological characteristics and texture were measured, respectively. All of the experiments were conducted in triplicate for each sample, and the final results from the mean of 3 independent experimental replications.ResultsThe carbonyl content of raw meat is 2.63 nmol/mg, and increased by 6.35 nmol/mg in 60 d. With the increase of protein oxidation, the proportion of protein ɑ helices decreases while β sheets increase, and β-turns and random coils remain basically unchanged. The lost sulfhydryl group is cross-linked in the form of disulfide bonds, significant difference between 4 and 50 d (P < 0.05). Through SDS-PSGE experiments found that the cross-linking of myosin heavy chain formed macromolecules to stay on the top of the separation glue, fully verified this point (Fig. 6). The sensitive amino acid tyrosine was cross-linked by dimerization of dimeric tyrosine and changed significantly from 0 to 30 d (P < 0.05). Changes in the surface hydrophobicity of the protein can be obtained, and the aggregation of the protein is greater than that of the structure during processing from 4 to 60 d. These changes cause contraction of myofibrils in both the transverse and longitudinal directions, which in turn leads to hardness, cohesiveness, gumminess and chewiness were significantly increased (P < 0.05) in air-dried yak meat, springiness and resilience decreased significantly (P < 0.05) during processing.These changes cause contraction of myofibrils in both the transverse and longitudinal directions, which in turn leads to hardness, cohesiveness, gumminess and chewiness were significantly increased (P < 0.05) in air-dried yak meat, springiness and resilience decreased significantly (P < 0.05) during processing.Fig. 6.Myofibrillar protien SDS-PAGE of dried yak meat.ConclusionWith the increase of protein oxidation of yak meat during non-artificial freeze-drying, myofibrillin molecules crosslink and aggregate in the form of disulfide bond and dimeric tyrosine. These changes cause the muscle fibers to contract both horizontally and vertically, which in turn leads to hardness, cohesiveness, gumminess and chewiness were increased significantly, and result in decreased springiness and resilience ultimately.

Quality of steak restructured from beef trimmings containing microbial transglutaminase and impacted by freezing and grading by fat level.

ObjectiveThe objective of this research was to evaluate the physico-chemical, microbiological and sensorial qualities of restructured steaks processed from beef trimmings (grade I and II) and frozen beef (fresh beef as control and frozen beef).MethodsBeef trimmings from commercial butcher were collected, designated into 4 treatments differing in beef trimmings grade and freezing, processed into restructured steaks with 1% microbial transglutaminase and then analyzed for product quality.ResultsThe results showed that all meat from different groups could be tightly bound together via cross-linking of myosin heavy chain and actin as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Microbial counts of psychrotrophic and mesophilic bacteria were not affected by treatments (p>0.05), and no detectable of thermophilic bacteria were found. Regarding effect of beef trimmings grade, steaks made from beef trimmings grade II (16.03% fat) showed some superior sensorial qualities including higher tenderness score (p<0.05) and tendency for higher scores of juiciness and overall acceptability (p<0.07) than those made from beef trimmings grade I (2.15% fat). Moreover, a hardness value from texture profile analysis was lower in steaks processed from beef trimmings grade II than those made from grade I (p< 0.05). Although some inferior qualities in terms of cooking loss and discoloration after cooking were higher in steaks made from beef trimmings grade II than those made from beef trimmings grade I (p<0.05), these differences did not affect the sensory evaluation. Frozen beef improved the soft texture and resulted in effective meat binding as considered by higher cohesiveness and springiness of the raw restructured product as compared to fresh beef (p<0.05).ConclusionThe results indicated the most suitable raw beef for producing restructured steaks without detrimental effect on product quality was beef trimmings grade II containing up to 17% fat which positively affected the sensory quality and that frozen beef trimmings increased tenderness and meat binding of restructured beef steaks.

Effect of oxygen concentration in modified atmosphere packaging on color and texture of beef patties cooked to different temperatures

Patties were made from raw minced beef after storage for 6days in modified atmosphere (0, 20, 40, 60, and 80% oxygen) to study the combined effect of oxygen concentration and cooking temperature on hardness and color. Increased oxygen concentrations generally led to larger (P<0.01) thiobarbituric acid-reactive substances (TBARS) values, greater (P<0.01) loss of free thiols and more formation of cross-linked myosin heavy chain. Hardness of cooked patties was generally lower (P<0.01) without oxygen. Premature browning of cooked patties was observed already at a relative low oxygen concentration of 20%. The internal redness of cooked patties decreased (P<0.05) with increasing oxygen concentrations and increasing cooking temperatures. Mean particle size (D(3,2)) of homogenized cooked meat generally increased (P<0.05) with increasing cooking temperatures and increasing oxygen concentrations, and particle size was correlated (r=0.80) with hardness of cooked patties.

Effect of Skin Wine Pomace and Sulfite on Protein Oxidation in Beef Patties During High Oxygen Atmosphere Storage

Meat storage in high oxygen atmosphere has been reported to induce protein oxidation reactions decreasing meat quality. The incorporation of antioxidants has been proposed to reduce the extent of these reactions. In this study, the ability of red and white skin wine pomaces as well as sulfites to inhibit protein oxidation were tested in beef patties stored for up to 15 days at 4 °C in a high oxygen atmosphere (70 % O2 and 30 % CO2). SO2 (300 ppm) effectively protected against protein oxidation measured as radical formation by electron spin resonance (ESR) spectroscopy, as thiol loss by the DTNB assay and as myosin heavy chain (MHC) disulfide cross-linking by SDS-PAGE. Pomace from red wine production with a total phenol of 9.9 mg gallic acid equivalent/g protected against protein radical formation and against MHC cross-linking, but not against thiol loss by addition of 2.0 % (w/w) to the beef patties. Pomace from white wine production with a total phenol of 4.0 mg gallic acid equivalent/g only protected against MHC cross-linking. For both types of wine pomace, protein modifications not seen for sulfite addition were observed and were proposed to involve covalent phenol addition to proteins. Red wine pomace may be an alternative to sulfite as a meat additive for protection of beef patties against protein oxidation.

Changes in gel properties and water properties of Nemipterus virgatus surimi gel induced by high-pressure processing

The effects of high-pressure processing (HPP) on gel properties and water properties of Nemipterus virgatus (N. virgatus) surimi gel, the correlation among spin–spin relaxation time (T2), water holding capacity (WHC) and gel properties were studied. The results show that breaking force, breaking displacement, rupture work and WHC of surimi gels increased and then decreased significantly as the pressure increased, and reached the maximum values at 400 MPa, larger than that from 0.1 MPa and heat-set samples. It was noteworthy that cooking loss, spin–spin relaxation time (T2), solubility and myosin heavy chain (MHC) bands intensity of N. virgatus surimi gel decreased and then increased significantly as the pressure increased, lower than that from 0.1 MPa and heat-set samples, and reached the minimum values at 400 MPa. In addition, a denser network structure of N. virgatus surimi gel was achieved at 400 MPa. It indicated that high pressure of 400 MPa not only contributed to WHC improvement of N. virgatus surimi gels, decreased cooking loss and solubility, but also forming a denser, micromesh-like, more uniform, and hierarchical 3D network structure via cross-linking of MHC. This structure resulted in the increase in WHC and improvement of gel properties.

Protein thiols undergo reversible and irreversible oxidation during chill storage of ground beef as detected by 4,4'-dithiodipyridine.

Quantification of protein thiols and disulfides in ground beef during storage under high-oxygen atmosphere at 4 °C was performed by thiol detection using 4,4'-dithiodipyridine (4-DPS) before and after disulfide reduction using sodium borohydride. Two independent storage trials were performed, and in trial 1, only reversible thiol oxidation was observed (thiol loss was 30%). In trial 2, irreversible thiol oxidation occurred during the first days of storage, while further loss of thiols was caused by reversible disulfide formation (thiol loss was 33%, of which ca. half was lost because of irreversible oxidation). The results were compared to sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis of cross-linked myosin heavy chain formed by disulfide bonding. Both methods confirmed increasing disulfide formation because of thiol oxidation in meat during storage, but the 4-DPS method showed higher disulfide percentages than the SDS-PAGE method (22.2 ± 0.3% and 8.5 ± 1.2%, respectively). The 4-DPS assay provides an accurate method to evaluate the thiol-disulfide redox state in meat.

Effect of Oxidized Myofibrils Protein Subjected to Mutiple Freeze-Thaw Cycles on N-Nitrosamine Formation in &lt;i&gt;In Vitro&lt;/i&gt; Model System

N-nitrosamine is a kind of carcinogenic substance, which is possibly formed in the reaction of nitrites with amino acids or secondary amines. Two in vitro model systems were designed to evaluate the influence of oxidized myofibrils protein subjected to repeated freeze-thaw cycles (0, 1, 2, 3, 4, 7, 10 times) on N-nitrosamine formation. Model system I contains diethylamine and sodium nitrite, while model system II contains only sodium nitrite as reaction solution. Oxidized myofibrils protein were added to both systems. The results revealed that as the number of freeze-thaw cycles increased, cross-linking of myosin heavy chains and the content of protein carbonyl increased, but the content of protein sulfydryl decreased, which indicates oxidization of protein occurred. The concentration of N-nitrosodiethylamine increased as the number of freeze-thaw cycles increased, especially after four cycles. Oxidized myofibrils protein promoted the formation of N-nitrosodiethylamine. The more the times of freeze-thaw cycles were subjected, the more oxidization of myofibrils protein occurred and the higher yield of the N-nitrosodiethylamine.

Contribution of Sarcoplasmic Proteins to Myofibrillar Proteins Gelation

Surimi, a refined protein extract, is produced by solubilizing myofibrillar proteins during the comminuting and salting stages of manufacturing. The resulting paste gels on heating to produce kamaboko or a range of analog shellfish such as crab claw, filament sticks, fish mushroom, and so on. The myosin molecule is the major myofibrillar protein in gelation. It is believed that washing steps during the traditional surimi process play an important role in enhancing the gel properties of the resultant kamaboko by removing water-soluble (sarcoplasmic, Sp-P) proteins. By contrast, some researchers claim that retaining Sp-P or adding it into the surimi gel network not only does not interfere with the action of myofibrillar proteins during the sol-gel transition step but also improves the gel characteristics of the resultant kamaboko. It seems that retention of Sp-P or their addition into raw surimi does enhance the textural properties of kamaboko gel perhaps by functioning as a proteinase inhibitor, particularly against trypsin and trypsin-like proteinases but this depends on the type of applied surimi process. Among different types of Sp-P, it has been claimed that some proteins such as endogenous transglutaminase (TGase) play a more important role than other Sp-P in bond formation, by catalyzing the cross-linking of myosin heavy chain (MHC) molecules during low-temperature setting of surimi, resulting a more elastic kamaboko gel.

The effects of high oxygen modified atmosphere packaging on protein oxidation of bovine M. longissimus dorsi muscle during chilled storage

Modified atmosphere packaging (MAP) extends the shelf life of beef, especially in the context of visual colour. High O2 MAP (70–80%) may cause quality deterioration through lipid and protein oxidation, the latter linked to a reduction in meat tenderness. The objective of this study was to investigate the effects of MAP in comparison to vacuum packaging (VP) on protein oxidation and subsequent tenderness of LD (M. longissimus dorsi) beef steaks during chilled storage (4°C) of periods up to 14days. Steaks were analysed for carbonyl content, free thiol groups, drip loss, Warner–Bratzler shear force (WBSF) and SDS–PAGE of extracted myofibrillar proteins. Free thiol groups were lower in high O2 MAP (80% O2/20% CO2) steaks, after 14days of storage, indicating protein oxidation compared to VP steaks. SDS–PAGE (non reducing conditions) showed the presence of high molecular weight cross linked myosin heavy chain aggregates in the high O2 atmosphere packaged steaks, which were absent in VP steaks.

Quality Characteristics of High Pressure-Induced Hake (Merluccius capensis) Protein Gels with and without MTGase

The effects of microbial transglutaminase (MTGase; 0.5%, w/w) and high hydrostatic pressure (HHP) on the quality of protein gels from unwashed mince of hake (Merluccius capensis) trimmings were studied. MTGase incorporation improved texture. Protein solubility was lower for those gels containing MTGase, as a result of myosin heavy chain cross-linking. HHP improved texture. Pressure level was the most important HHP parameter, since higher levels (300 vs. 100 MPa) augmented gel strength (GS). A positive synergistic effect of MTGase and HHP was found for some properties, such as GS, yielding improved gels from a raw material that otherwise shows poor gelation.

Differential effects of peroxynitrite on contractile protein properties in fast- and slow-twitch skeletal muscle fibers of rat

Oxidative modification of contractile proteins is thought to be a key factor in muscle weakness observed in many pathophysiological conditions. In particular, peroxynitrite (ONOO(-)), a potent short-lived oxidant, is a likely candidate responsible for this contractile dysfunction. In this study ONOO(-) or 3-morpholinosydnonimine (Sin-1, a ONOO(-) donor) was applied to rat skinned muscle fibers to characterize the effects on contractile properties. Both ONOO(-) and Sin-1 exposure markedly reduced maximum force in slow-twitch fibers but had much less effect in fast-twitch fibers. The rate of isometric force development was also reduced without change in the number of active cross bridges. Sin-1 exposure caused a disproportionately large decrease in Ca(2+) sensitivity, evidently due to coproduction of superoxide, as it was prevented by Tempol, a superoxide dismutase mimetic. The decline in maximum force with Sin-1 and ONOO(-) treatments could be partially reversed by DTT, provided it was applied before the fiber was activated. Reversal by DTT indicates that the decrease in maximum force was due at least in part to oxidation of cysteine residues. Ascorbate caused similar reversal, further suggesting that the cysteine residues had undergone S-nitrosylation. The reduction in Ca(2+) sensitivity, however, was not reversed by either DTT or ascorbate. Western blot analysis showed cross-linking of myosin heavy chain (MHC) I, appearing as larger protein complexes after ONOO(-) exposure. The findings suggest that ONOO(-) initially decreases maximum force primarily by oxidation of cysteine residues on the myosin heads, and that the accompanying decrease in Ca(2+) sensitivity is likely due to other, less reversible actions of hydroxyl or related radicals.

High-oxygen modified atmosphere packaging system induces lipid and myoglobin oxidation and protein polymerization

Beef steaks from longissimus lumborum, semimembranosus, and adductor muscles (n=10; respectively) were cut at 24h postmortem, randomly assigned to either high-oxygen modified atmosphere packaging (HiOx-MAP; 80% O(2), 20% CO(2)) or vacuum (VAC), and displayed for 9days at 1 degrees C. HiOx-MAP packaged beef steaks had a rapid increase in lipid oxidation and a decrease in color stability during display. The steaks in HiOx-MAP had significantly lower tenderness and juiciness scores, and higher off-flavor scores compared to steaks in VAC. HiOx-MAP condition did not affect the postmortem degradation of troponin-T or desmin. Furthermore, autolysis of micro-calpain was not influenced by packaging. SDS-PAGE, immunoblotting, and diagonal-PAGE revealed oxidative cross-linking of myosin heavy chain in meat packaged in HiOx-MAP. These results suggest that the HiOx-MAP system may negatively affect meat quality characteristics by inducing lipid and myoglobin oxidation and cross-linking/aggregation of myosin by protein oxidation.

High-oxygen packaging atmosphere influences protein oxidation and tenderness of porcine longissimus dorsi during chill storage

The effect of modified atmosphere packaging (70% O 2/30% CO 2) and skin packaging (no oxygen) on protein oxidation and texture of longissimus dorsi was investigated during storage for 14 days at 4 °C. High oxygen atmosphere resulted in reduced tenderness and juiciness and SDS–PAGE revealed cross-linking of myosin heavy chain through disulfide bonding, and the content of protein thiols was reduced indicating protein oxidation. Myofibril fragmentation was reduced in meat stored in high oxygen atmosphere indicating less proteolysis and/or cross-linking of proteins. Protein carbonyl content was not affected by the packaging atmospheres. This study shows that packaging in modified atmosphere containing a high level of oxygen can result in protein cross-linking and reduced tenderness and juiciness of the meat.