Experimental Study On The Effects Of Pulse Electric Field Combined With Metal Ions On The Microstructure And Functional Properties Of Protein

Pulsed electric field?PEF,for short?is a new non-thermal processing technology.PEF has many advantages,such as instantaneous efficiency and uniformity of treatment.Some works investigate the effects of pulsed electric field on protein,such as unfolding,refolding and aggregation?protein denaturation?and self-assembly?undenatured protein?.Some studies also indicate that the pulse electric field,along with metal ion,will change the structure of protein,even protein could emerge as nanotubes.However,Studies about protein basic mechanism,as well as the effects on other protein properties has been gained few attention.Divalent metal ions exert a greater impact when pulsed electric field interacts with metal ions in some studies.In this study,ovalbumin has been taken as the research object,which also has been injected four kinds of metal ions(Ca²⁺,Mn²⁺,Cu²⁺,Ba²⁺)to conduct pulse treatment respectively.Setting pulsed time as an influencing factor,this study explores the effect of pulsed electric field,together with metal ions,on the microstructure and functional properties of protein.This experiment tries to analyze the specific PEF effects in changing the index via testing Ph index,solubility,turbidity,particle size,surface tension,surface hydrophobic properties,conductivity,Zeta potential,redox potential and chemical properties,emulsification and foaming properties,detection and Raman spectroscopy and infrared spectroscopy analysis of the specific impact index.Main results are as follows:1.The combination of metal ions and protein reduces pH index of protein solution but increases its electrical conductivity.The impact could be sequenced as follows:Mn²⁺>Ba²⁺>Cu²⁺>Ca²⁺.Pulsed electric field exerts minimum effect on ovalbumin pH as well as electrical conductivity injected metal ions.2.The effects of pulsed electric field with metal ions on protein molecular structure have been analyzed Raman and infrared spectroscopy.Metal ions and ovalbumin molecules have presented varied chelation at 1700¹200 cm^-1,among the four metal ions,chelation of Mn²⁺was the strongest while Ca²⁺was the weakest.Meanwhile,PEF injected metal ions will expand protein molecular structure.In conclusion,PEF could enhance the effect of metal ions and chelate PEF ovalbumin,but the treatment time was 1695?s,Mn²⁺and Cu²⁺and protein chelating metal ion binding weakened;the pulse energy could promote the unfolded protein molecular structure,when the pulse time exceeded 1695?s,the protein molecules started polymerization.Molecular structure transformation of protein may lead to a change of its hydrophobicity.Measuring the surface hydrophobicity and surface tension,the index shows that the combination of metal ions and protein would enhance its surface hydrophobicity.A certain pulse energy could motivate the combination of protein and metal ions,which also improve the surface hydrophobicity of protein.4.Surface hydrophobicity is the main driving force to maintain the third structure of protein.Surface tension,solubility,and charge can all change the stability of the protein solution.after detecting soluble protein,Zeta potential,particle size,turbidity,the index reveals that protein combined with metal ions increases soluble protein weight,while this combination lower system turbidity,and also influences the whole chemical environment around protein solution as a result of particle size reducing,and destruction of the protein solution stability.In a certain treatment time,pulsed electric field enhances the effect of metal ions on protein soluble protein and turbidity,pulsed electric field also increases the stability of protein solution.However,the content of soluble protein decreased and turbidity increases when the pulse time increases to 1695?s,PEF cooperates with metal ions to promote the self-assembly of protein molecules and increase the particles in the protein solution.When the pulse duration lasts too long,the aggregation and denaturation of protein is changed,and the stability of solution also decreases.The functional properties of proteins are influenced by the structure and physicochemical properties.Adding metal ions improves the foaming and emulsifying properties of the protein.A certain pulse energy treatment can improve the foaming and emulsifying properties of the protein,while a long pulse time may lead to the decrease of its functional properties.