Extraction and Characterization of Myofibrillar Proteins from Different Meat Sources:A Comparative Study

In the present study,myofibrillar proteins were extracted from the meat proteins of beef,lamb,chicken,tuna and emperor fish using non-denaturation method,and their physico-chemical and rheological properties were assessed.The myofibrillar proteins of beef,emperor and lamb samples had higher percentage of protein extractability than tuna and chicken samples.The tuna sample showed significantly higher bound bromophenol blue(BPB)value while lamb samples showed lower value(P<0.05).The myofibrillar protein of chicken sample was found to have more ionic and hydrogen bonds than all other myofibrillar samples.The disulphide bonds in tuna and lamb myofibrillar protein samples were significantly higher than other three samples(P<0.05).The myofibrillar protein samples showed major bands myosin heavy chain,α-actinin,desimin,actin,troponin,tropomyosin and myosin light chain with wider molecular weight distribution in the range of 20-200 ku.The myofibrillar proteins exhibited Newtonian and shear thickening nature behaviour at lower protein concentration(1 mg/mL)as revealed by flow profile and visco-elastic analysis using rheometer.

Dynamic viscoelastic behaviour,gelling properties of myofibrillar proteins and histological changes in shrimp(L.vannamei)muscles during ice storage

Changes in protein quality during ice storage affects the muscle structure,the textural quality,functional properties and the eating quality.Dynamic viscoelastic behaviour and gelling properties ofmeat proteinsin relation to histological changes in white leg shrimp muscles were assessed for 14 days in ice storage.Reduction in Ca2+ATPase activity of fresh myofibrillar protein(MFP),fading of myosin banding pattern and increased gapping in myofibrils were clearly observed with progress of storage.The quality indices of the shrimp muscle were well correlated with histological and functional properties as a function of ice storage.Solubility of fresh MFP was 86.76%which decreased to 77.06%on the 14th day of storage period.Emulsion capacity found to increase during storage period.Gel strength of white leg shrimp meat was low(81±14 g cm)and further,reduced nearly 60%compared to fresh sample at the end of storage.The considerable reductions(from 535.77 kPa to 246.56 kPa)in storage modulus values were evident of diminishing elasticity and gelling ability of the meat due to ice storage.Therefore,this study usherd that the histological deterioration in myofibrils may be used as an indication of diminishing biochemical quality and gelling behaviour of the proteins.

Effect of sodium starch octenyl succinate-based Pickering emulsion on the physicochemical properties of hairtail myofibrillar protein gel subjected to multiple freeze-thaw cycles

A Pickering emulsion based on sodium starch octenyl succinate(SSOS)was prepared and its effects on the physicochemical properties of hairtail myofibrillar protein gels(MPGs)subjected to multiple freeze-thaw(F-T)cycles were investigated.The whiteness,water-holding capacity,storage modulus(G')and texture properties of the MPGs were significantly improved by adding 1%-2%Pickering emulsion(P<0.05).Meanwhile,Raman spectral analysis demonstrated that Pickering emulsion promoted the transformation of secondary structure,enhanced hydrogen bonds and hydrophobic interactions,and promoted the transition of disulfide bond conformation from g-g-g to g-g-t and t-g-t.At an emulsion concentration of 2%,theα-helix content decreased by 10.37%,while theβ-sheet content increased by 7.94%,compared to the control.After F-T cycles,the structure of the MPGs was destroyed,with an increase in hardness and a decrease in whiteness and water-holding capacity,however,the quality degradation of MPGs was reduced with 1%-2%Pickering emulsion.These findings demonstrated that SSOS-Pickering emulsions,as potential fat substitutes,can enhance the gel properties and the F-T stability of MPGs.

Improvement of gelation properties of myofibrillar proteins from porcine longissimus dorsi muscle through microwave combined with air convection thawing treatment

The effects of the microwave combined with air convection thawing(MAT)on the gelling properties of pork myofibrillar proteins(MPs)were further studied and compared with those of fresh meat(FM),and single thawing methods(microwave thawing(MT)and air convection thawing(AT)).Results revealed that the thawing methods,excluding MAT,induced deterioration in the gelling properties of MPs.There was no significant difference(p>0.05)in the water holding capacity(WHC),cooking loss,whiteness,and strength of gel samples subjected to MAT and those of FM samples,demonstrating that the gelling properties were retained after MAT.As well,protein aggregation was limited,since MAT reduced the change in zeta potential and turbidity compared to that observed with MT or AT.The dynamic rheology and scanning electron microscopic results were relatively consistent,revealing that among the different thawing techniques,MAT had the least negative impact on the microstructure of MPs gel,leading to the generation of a more elastic and uniform gel structure than that of the MT or AT gels.Moreover,MAT resulted in higher water retention in the gels than that achieved with MT or AT.These findings indicated that MAT improved the gelling properties of MPs,thereby confirming the suitability of this treatment for use in the meat processing industry.

Oxidative mechanism of chicken wooden breast myofibrillar protein

To explore the oxidation mechanism of wooden breast myofibrillar protein(WBMP),oxidative breast MP(OBMP)was obtained from different doses(3,10,and 20 mmol/L)of H2O2 oxidized normal breast MP(NBMP).The results showed that the Zeta-potential,particle size,solubility,sulfhydryl,and carbonyl contents of OBMP-3(3 mmol/L,low-dose free radicals)and WBMP were similar.Fluorescence spectrum analysis showed that the oxidation of low-dose free radicals led to a significant increase in the surface hydrophobicity(from 214.03±10.03 to 393.50±10.33)and tryptophan fluorescence intensity(from 185.71 to 568.32).In addition,theα-helix content of WBMP decreased significantly from(37.46±1.15)%(NBMP)to(34.70±2.04)%,whileβ-sheet and random coil contents increased significantly(P<0.05)from(14.37±0.69)%and(22.24±0.78)%(NBMP)to(17.70±0.87)%and(25.20±1.47)%(WBMP).In summary,low-dose free radical oxidation attacks protein groups,inducing secondary and tertiary structural changes,leading to the formation of WBMP.This work will provide a theoretical basis at the molecular level for exploring the mechanism of functional degradation of WBMP.

The effect of protein oxidation on the formation of advanced glycation end products after chicken myofibrillar protein glycation

Investigation that protein oxidation to the formation of advanced glycation end products(AGEs)after chicken myofibrillar protein glycation is limited.Models of protein oxidation induced by different concentrations of hydroxyl radicals(·OH)were developed after the chicken myofibrillar protein mild glycation(MPG).Results exhibited that levels of AGEs and surface hydrophobicity(H_(0))steadily increased with the a ddition of h ydrogen peroxide(H_(2)O_(2))concentration.However,levels of s ulfhydryl group,free amino group,and particle size gradually decreased with the H_(2)O_(2)concentration.The protein carbonyl value increased in H_(2)O_(2)concentration until 10 mmol/L.Pearson's correlation indicated that MPG structure modification(unfolding and degradation)induced by protein oxidation were significantly positively correlated with AGEs concentration(P<0.05).Finally,a mechanism was proposed to hypothesize t he effect of protein oxidation on the formation of AGEs under MPG conditions.

Characteristic and effect analysis of protein and peptide in Cantonese cured meat processing

The aim of this work was to explore the physicochemical and structural properties,lipid oxidation and antioxidant capacity of the peptides extracted from Cantonese cured meat and as well as to investigate the effect of drying time on the sarcoplasmic and myofibrillar proteins of Cantonese cured meat.The results suggested that salting out,protein oxidation and heat treatment were closely related to surface hydrophobicity and the secondary structure of peptides was changed by processing.And the peroxide value and the value of tributyltin compounds were different in evaluating the degree of lipid oxidation.Glu and His were the major amino acid.The approximate molecular weights of the sarcoplasmic proteins and myofibrillar proteins ranged from 31 kDa to 50 kDa and 66 kDa,respectively.The results indicated that reducing the levels of protein oxidation and improvement of the antioxidant properties should be of great interest to preserve the nutritional quality of meat products and prolong preservation period.

Effects of phosphorylated ovalbumin on the quality of pork myofibrillar protein gel:an insight into gelling and physicochemical properties

This study aimed to investigate the effects of phosphorylated-ovalbumin(P-OVA)at different concentrations(0.5%and 1.0%)on the gel properties of pork myofibrillar protein(MP).The results showed that the textural properties such as gel hardness,cohesiveness,springiness and chewiness were improved with P-OVA addition at 0.5%.The water holding capacity(up to 75.89%)and gel strength(up to 168.56 g·mm)of MP gel were markedly increased after P-OVA addition.The absolute value of zeta potential reached 13.85 mV and maximum hydrophobicity(15.2μg)resulted from the addition of 0.5%P-OVA.The storage modulus(G’)and loss modulus(G’’)of MP gel were significantly increased from 50°C,and the G’and G’’significantly increased after 1.0%P-OVA addition,evidencing that the cross-linking effect of MP protein gel was enhanced.In addition,the P-OVA addition improved the structure of MP gel protein by reducing theα-helix,while increasing theβ-sheet and the r-value(the ratio between two ultraviolet second-derivative peak-to-trough distances),which further promoted the uniform and compact gel network structure.This work demonstrated that P-OVA is a highly effective modifier that significantly improves the quality of MP gel.From a view of practice,0.5%P-OVA is the optimal addition amount.

Effectiveness of L-arginine/L-lysine in retarding deterioration of structural and gelling properties of duck meat myofibrillar protein during freeze-thaw cycles

This study aimed to investigate the protective effects of L-arginine(L-arg)and L-lysine(L-lys)on the structure and gel properties of myofibrillar protein(MP)in duck meat during several freeze-thaw(F-T)cycles.The analysis of the Ca2+-ATPase activity as well as total sulfhydryl and carbonyl contents demonstrated that L-arg and L-lys could slow down the oxidative denaturation of MP during F-T cycles.Circular dichroism,fluorescence spectroscopy,and rheology measurements indicated that L-arg and L-lys improved the stability of the secondary and tertiary structure of MP and preserved its gel properties.In summary,L-arg and L-lys had the potential to preserve the structural stability and gel properties of MP during F-T cycles.

Effects of citrus fiber on the emulsifying properties and molecular structure of mutton myofibrillar protein:An underlying mechanisms study

The effects of water-soluble citrus fiber(SCF)and water-insoluble citrus fiber(ICF)on emulsifying properties and molecular structure of the mutton myofibrillar protein(MP)were studied.The emulsifying activity index and emulsifying stability index of MP emulsion,treated with 5%SCF significantly improved to 36.80%and 65.27%,respectively.The droplet size of the emulsion significantly reduced,forming smaller and more uniformly dispersed droplets.SCF promoted the unfolding of MP,and showed a significant increased(p<0.05)in total sulfhydryl content and fluorescence intensity,but a significant decreased(p<0.05)in surface hydrophobicity.Besides,SCF treatment showed a significant reduction(p<0.05)inα-helix content and a significant enhancement(p<0.05)inβ-turn content of the MP secondary structure.The EAI,ESI,and solubility of MP significantly decreased after the addition of ICF,but there was no significant change in the secondary structure.These data demonstrated that,the addition of the appropriate amount of SCF could improve the emulsifying properties and molecular structure of MP.

Effects of freeze-thaw cycles on physicochemical properties and structure of cooked crayfish (Procambarus clarkii)

To explore the damage mechanisms of freeze-thaw cycles on cooked crayfish in frozen storage, changes in the phys-icochemical properties and structure of cooked crayfish during the freeze-thaw cycles were investigated. The phys-icochemical properties of cooked crayfish changed significantly after five freeze-thaw cycles. The moisture content, water holding capacity, pH, and textural properties were decreased, while the total color difference, drip loss, and pro-tein and lipid oxidation were significantly increased (P < 0.05). LF-NMR and MRI verified the water loss, and SDS-PAGE showed denaturation/degradation of myofibrillar proteins (MPs). Multiple freeze-thaw cycles promoted the transition from α-helix to β-turn in the secondary structure, the unfolding of tertiary structure, and a significant change in the chemical forces of MPs. SEM results revealed a disruption in the microstructure of muscle fibers. Repeated freeze-thaw cycles reduced the moisture content and distorted the structure of MPs in cooked crayfish, resulting in the disruption of physicochemical properties and its structure.

Low-temperature combined with high-humidity thawing improves the water-holding capacity and biochemical properties of Portunus trituberculatus protein

This study compared the effects of conventional thawing methods(water immersion thawing(WIT,(25±1)℃),natural air thawing(AT,(25±1)℃,relative humidity(RH(65±2)per cent),refrigerator thawing(RT,4℃,RH(80±2)per cent)and low-temperature(LT)combined with high-humidity thawing LT,-1℃to 1℃(LT-1-1),2-4℃(LT2-4),5-7℃(LT5-7)and 8-10℃(LT8-10),RH>95 per cent)on the water-holding capacity,lipid oxidation and biochemical properties of Portunus trituberculatus(P.trituberculatus)myofibrillar protein.The results showed that WIT and AT significantly decreased the water-holding capacity while dramatically increasing lipid oxidation,protein oxidation and degeneration,resulting in serious P.trituberculatus quality deterioration.High humidity was beneficial for P.trituberculatus\.ha\A/\ng.The thawing time of P.trituberculatus under the conditions of LT2-4 was only 39.39 per cent of that of conventional air thawing at 4℃(RT),and the LT2-4 samples not only maintained better water-holding capacity but also had an obviously reduced degree of lipid oxidation,protein oxidation and denaturation.Thawed samples LT2-4 and LT5-7 provided better maintenance of P.trituberculatus quality than the LT-1-1 and LT8-10 samples.The best quality was exhibited after thawing at 2-4℃.The levels of thiobarbituric acid reacting substances,carbonyl content and surface hydrophobicity observably decreased in these samples,while the total sulfhydryl contents dramatically increased compared to those of conventionally thawed samples,indicating lower lipid oxidation and protein oxidation.Moreover,the Ca2+-ATPase activity of the sample thawed at 2-4℃(2.06 μmol Pi/mg prot/h)was markedly higher than that of samples subjected to WIT and AT.The product qualities observed after thawing at-1℃to 1℃,5-7℃and 8-10℃under LT were comparable to that observed by RT.Considering its thawing efficiency and product quality,LT is a suitable method for the thawing of P.trituberculatus,and the ideal thawing conditions were LT at 2-4℃.