Effects Of Dhpm Treatment And Salecan Addition On The Physical And Chemical Properties And Structure Of Myofibrils Protein Under Low-salt Condition

Myofibrillar protein is a salt-soluble protein.It has poor physical and chemical properties in the low-salt conditions and water,which limits its processing and utilization,especially in fluids and protein beverages.Therefore,it is of great significance to improve the functional properties of the protein under low-salt conditions.Dynamic high pressure microfluidization(DHPM)is a "green" processing technology developed in recent years.It has significant effects on the modification of macromolecules,so it has attracted the attention of researchers.At present,the influence of the interaction between polysaccharides and proteins on food systems is also a hot research topic.Polysaccharides not only have biologically active functions,but also play an important role in food quality.Salecan is a water-soluble ?-1,3-glucan with a variety of biological activities and has broad application prospects in food.However,there are few reports on the citation of Salecan in food at present.This experiment explored the effects of DHPM treatment and Salecan addition on the physical and chemical properties and structure of myofibril protein in the low-salted systerm,laying a foundation for the development of proteoglycan compound system food.(1)The amount of Salecan added has a certain effect on the physical and chemical properties of myofibrillar protein in the low-salted systerm under the DHPM treatment(20,000 psi,9times).When the addition of Salecan is within 0.4%(w/v),the solubility of myofibrillar protein under DHPM treatment(20000psi,9 times)is 45.16-43.45%,with no significant difference(P>0.05),but the addition reaches at 0.5%(w/v),the protein solubility is significantly reduced(P<0.05);Salecan has no significant effect on the protein surface active sulfhydryl content(P>0.05)when the addition of Salecan is between0 and 0.3%(w/v),but the addition amount reaches at 0.4%(w/v),the protein surface active sulfhydryl content decreased significantly(P<0.05).With the increase in the amount of Salecan addition,the hydrophobicity of the protein surface and the absolute value of the zeta-point of the system particles showed a significant increase first and then a significant decrease(P<0.05),while the zeta-particle size and appearance viscosity and shear stress of the system particles show a gradual increase trend,which is the result of thickening of Salecan effect and the interaction of protein and polysaccharides.But when the amount of Salecan added is too much,it will reduce the treatment effect of DHPM on the system particles.The effect is better when the amount of Salecan added is 0.3%(w/v).(2)The amount of Salecan added has a certain effect on the structure of low-salt myofibrillar protein under DHPM conditions(20,000 psi,9 times).CLSM showed that when 0.3%(w/v)Salecan was added to the system,the protein and polysaccharides were observed to overlap each other.When 0.5%(w/v)Salecan was added to the system,the unfolded protein and polysaccharides re-aggregated and the molecular The particle size becomes larger.SDS-PAGE showed that under DHPM treatment,adding Salecan had no effect on myofibril protein electrophoresis bands.The endogenous fluorescence spectrum shows that the maximum fluorescence emission wavelength of the protein after DHPM treatment has a red shift,and the maximum fluorescence intensity is also significantly increased;However,the addition of Salecan will make the maximum fluorescence emission wavelength of the protein blue shift.Regarding the secondary structure,the addition of Salecan will increase the ?-helical structure content of myofibrillar protein,and the ?-turn will be the opposite.It shows that the addition of Salecan will change the conformation of myofibrillar protein under DHPM treatment.(3)For protein complex systems and pure protein systems,DHPM treatment can significantly improve the solubility,surface hydrophobicity,active sulfhydryl content and zeta-potential of the protein(P<0.05),and significantly reduce the zeta particle size(P<0.05).With the gradual increase of DHPM treatment pressure,protein solubility and sulfhydryl content showed a significant increase(P<0.05);surface hydrophobicity and zeta-particle size showed a significant decline(P<0.05);The absolute value of zeta-potential increased first and then decreased(P<0.05).With the increase of the number of DHPM treatments,the solubility and active sulfhydryl content of the protein increased significantly,and the zeta particle size decreased significantly(P<0.05);the hydrophobicity and the absolute value of zeta-potential first increased significantly and then decreased significantly(P<0.05).The viscosity and shear stress of the system decrease continuously with the increase of pressure and frequency.Under the same DHPM treatment conditions,compared with the pure protein system,the protein solubility of the composite system(P<0.05);the surface hydrophobicity,the particle size of the system,the absolute value of zeta-potential,and the viscosity and shear force of the system are significantly increased(P<0.05);The content of active sulfhydryl groups increased significantly under certain DHPM treatment conditions(P<0.05).It shows that the pressure and times of DHPM treatment have a significant impact on the physical and chemical properties of the protein and polysaccharide system.(4)After DHPM treatment,the large protein aggregates are broken and disappeared,and the particle size of the protein becomes smaller and tends to be consistent.The distribution in the system is more uniform,and it is observed that the protein and polysaccharides overlap;the maximum absorption wavelength of the protein has a red shift,The maximum absorbed light intensity is also significantly increased.With the increase of DHPM treatment pressure and nunber,the protein bands with molecular weight between 200 k Da and 120?150k Da are gradually degraded and disappeared,and many protein bands with molecular weight between 60?120k Da are added.In the secondary structure,the ?-helix content of the ordered structure gradually decreased,and the ?-turn and random coil content of the disordered structure increased significantly.When the pressure reaches 20,000 psi and the number of times reaches 9 times,the content of electrophoretic bands and secondary structure does not change.Under the same DHPM treatment conditions,the electrophoresis bands of the composite system are no different from those of the pure protein group,but the ultraviolet absorption light intensity is significantly increased,and the content of ?-helical structure is higher than that of the pure protein group.The irregular curling showed the opposite.In summary,DHPM treatment can break the protein aggregates,reduce the particle size and molecular weight,stretch the protein,expose a large number of functional groups,increase the electrostatic interaction,and further increase the solubility of the protein,and improve the physical and chemical properties of the protein and the system stability.Under DHPM treatment,Salecan can interact with myofibrillar protein,in a simple physical entanglement or non-covalent bond combination,which leads to changes in the physical and chemical properties and structure of the myofibrillar protein.However,excessive addition of Salecan will reduce the effect of DHPM on treatment effect of the system particles.All in all,DHPM can make the proteoglycan complex system uniform and stable,which is of great significance to the development of myofibril protein products.