The Influence Of Partial Replacement Of NaCl By KCl, CaCl₂ And Amino Acids On The Structural And Functional Properties Of Duck Proteins

Duck meat products are sweet,refreshing and nutritious.They have been loved by consumers for a long time.However,most traditional duck products have high salt content.Studies have shown that excessive salt intake can cause high blood pressure,increase the risk of cardiovascular disease and kidney disease,and affect human health.This not only has hidden dangers to human health,but also weakens the purchasing power of consumers on duck meat products.Therefore,it is imperative to investigate the impact of salt and salt substitutes on duck meat products.In view of the current research is mainly on the influence of salt and its substitutes on the processing characteristics of poultry meat products,there are few studies on the mechanism of protein changes.In this paper,fresh duck meat was used as raw material to explore the effects of different NaCl concentration on the structural and functional properties of duck myofibrillar proteins,and explored the relationship between structural and functional properties of myofibrillar proteins.Then,in order to reveal the effect of different ions and amino acids on the structural and functional properties of duck myofibrillar proteins,the concentration of NaCl was fixed,and KCl,CaCl₂,and amino acids?lysine,histidine?were used as surrogates,the sequential substitution of NaCl was performed.Finally,the effects of KCl,CaCl₂ and amino acids?lysine,histidine?on the duck meat quality were investigated.The main research contents and conclusions are as follows:?1?The structural and functional characteristics of duck myofibrillar protein at different NaCl concentrations were studied.The results showed that:The structural and functional properties of myofibrillar protein are affected by NaCl concentration.When the concentration of NaCl was less than 0.2mol/L,the structure and functional properties of myofibrillar protein in duck meat were not significantly different?p<0.05?.When the concentration of NaCl was at 0.4⁰.8mol/L,with the increase of NaCl concentration,the content of active sulfhydryl representing the structural characteristics of duck myofibrillar protein increased significantly?p<0.05?,the surface hydrophobicity decreased significantly?p<0.05?,the dissolution rate of myofibrillar protein increased,and the?-helix content was added;.The solubility representing the functional properties of duck myofibrillar protein increased significantly?p<0.05?,turbidity was significantly decreased?P<0.05?,and the hardness and water retention of myofibrillar protein increased significantly?p<0.05?.?2?The influence of partial replacement of NaCl by KCl,CaCl₂ and amino acids on the structural and functional properties of duck proteins were studied.The results showed that:When NaCl addition amount was fixed to 3.5%,the effect of 10⁵0%KCl substion the structure and functional properties of duck myofibrillar protein was similar to that of 100%NaCl.The sulfhydryl content,surface hydrophobe content,protein band degradation,?-helix content,and solubility,turbidity,and gel properties of myofibrillar proteins did not show significant changes?p>0.05?.When KCl substitution ratio was fixed to 30%,after the successive substitution of NaCl by 10²5%CaCl₂,compared with the control group?70%NaCl+30%KCl?,the changes in the structure and function of duck myofibrillar protein were influenced by the CaCl₂ substitution ratio.When the CaCl₂ substitution ratio was 15 to 25%,the total sulfhydryl content,active sulfhydryl content of myofibrillar protein was significantly decreased?p<0.05?,and the surface hydrophobic content significantly increased?p<0.05?.the degree of troponin degradation increased;?-helix content decreased,and?-sheet and random coiling content increased,indicating that certain substitution ratio of CaCl₂ could affect the conformation of myofibrillar protein secondary structure;compared with the control group?70%NaCl+30%KCl?,the solubility and turbidity of the 15 to 25%CaCl₂ replacement group increased significantly?p<0.05?,and the gel hardness and water retention of the 10 to 25%replacement group increased significantly?p<0.05?.When the KCl substitution ratio was fixed to 30%and NaCl was successively substituted by 10 to 25%CaCl₂,compared with the control group?70%NaCl+30%KCl?,the changes in the structure and function of duck myofibrillar protein were influenced by the CaCl₂ substitution ratio.With the substitution ratio of CaCl₂,when the CaCl₂ substitution ratio was 15 to 25%,the total sulfhydryl content,active thiol content of myofibrillar protein was significantly decreased?p<0.05?,and the surface hydrophobic content was significantly increased?p<0.05?.the degree of troponin degradation increased;?-helix content decreased,and?-sheet and random coiling content increased,indicating that certain substitution ratio of CaCl₂ could affect the conformation of myofibrillar protein secondary structure;compared with the control group?70%NaCl+30%KCl?,the solubility and turbidity of the15²5%CaCl₂ replacement group increased significantly?p<0.05?,and the gel hardness and water retention of the 10²5%CaCl₂ replacement group increased significantly?p<0.05?.When the KCl and CaCl₂ substitution ratio was fixed to 30%and 15%,respectively.After the successive substitution of 3¹2%amino acid complexes for NaCl,compared with the control group?55%NaCl+30%KCl+15%CaCl₂?,the total sulfhydryl content and the active sulfhydryl content decreased significantly?p<0.05?,the surface hydrophobic content significantly increased?p<0.05?when the substitution ratio was6¹2%.SDS-PAGE electrophoresis showed that the degree of myosin degradation increased,the?-helix content decreased,and the content of?-sheet and random coiling content increased when the substitution ratio was more than 9%,indicating that the amino acids of a certain substitution ratio would affect the stability of the second grade structure of myofibrillin.Compared with the control group?55%NaCl+30%KCl+15%CaCl₂?,when the amino acids substitution ratio was6¹2%,the solubility of myofibrillar protein increased significantly?p<0.05?,the turbidity value decreased significantly?p<0.05?,the gel hardness and water retention increased significantly?p<0.05?.?3?The influence of partial replacement of NaCl by KCl,CaCl₂ and amino acids on on duck meat quality were studied.The results showed that:When NaCl addition amount was fixed to 3.5%,and after the successive substitution of NaCl by 10⁵0%KCl,with the increase of the KCl substitution ratio,the salt content of duck meat decreased significantly?p<0.05?,the change of water content was not significant?p>0.05?,the change of hardness value was not significant?p>0.05?,and the difference of total amino acids in the 10⁴0%KCl substitution group was not significant?p>0.05?.The total amino acids in the 50%KCl substitution group decreased significantly?p<0.05?,and the contents of lysine,alanine,leucine and glutamate decreased significantly?p<0.05?.When KCl substitution ratio was fixed to 30%,after the successive substitution of NaCl by 10²5%CaCl₂,with the increase of CaCl₂ substitution ratio,the salt content and water content of duck meat decreased significantly?p<0.05?,and the total amount of amino acids was not significant?p>0.05?when the CaCl₂ substitution ratio was below 15%,and the total amount of amino acids increased significantly?p<0.05?when CaCl₂ substitution ratio was above 20%?p<0.05?,the content of lysine,leucine,glutamic acid and aspartic acid was significantly higher than that of the unsubstituted group?p<0.05?.When the substitution ratio of KCl and CaCl₂ was fixed to 30 and 15%,respectively.after the successive substitution of NaCl by 3¹2%amino acid,with the increase of the amino acid substitution ratio,the salt content in duck meat decreased significantly?p<0.05?,the water content increased significantly?p<0.05?,and the hardness value was significantly reduced?p<0.05?.But the total amino acids in duck meat did not show significant differences?p>0.05?,and the content of glutamic acid,lysine and histidine increased significantly?p<0.05?when the amino acid substitution group was more than 9%.It maybe showed that amino acid substitution only affects the content of individual amino acids,but had no significant effect on the total amount of amino acids.