| When polyphenols are added as natural antioxidants to meat products,they easily interacted with proteins.At higher concentrations of polyphenols,protein structure unfolding,gel strength and water retention are deteriorated.Therefore,it was very necessary to find a method to inhibit the interaction between polyphenols and proteins.At present,there were few studies on this aspect.The main methods for inhibiting the interaction between polyphenols and proteins were glycosylation and addition of polysaccharides.Previous studies have shown that high concentrations of catechins change the conformation of myofibrillar proteins,while gel strength and water retention decrease.Flaxseed gum was a natural hydrophilic colloid with excellent water retention,gelation and emulsifying properties.Therefore,this paper prepared a catechin-myofibrillar protein mixed system with catechin concentrations of 0,50,100 ?mol/g protein,and then added 0.1%,0.2%,0.3%,0.4% flaxseed gum.To study the effects of flaxseed gum on protein structure,cross-linking and emulsification gel properties in catechin-myofibrillar protein mixed system.The main conclusions were as follows:1.Taking catechin-myofibrillar protein hybrid gel as research object,study the effect of flaxseed gum on gel properties,and determine gel strength,water retention,hydration characteristics,rheological properties and secondary structure of gel.The results showed that the gel strength was the highest when the flaxseed gum content was 0.1%;the flaxseed gum content was 0.4%,and the catechin concentration was 100 ?mol/g,the gel water retention was the best;Flaxseed gum increased the ability of the gel to bind water;When the gel was finally formed,the storage modulus G' increased as the amount of flaxseed gum added increases;The addition of flaxseed gum increased the ?-helix content in the gel,while the ?-sheet,?-turn and random crimp content decreased.Therefore,flaxseed gum improved the adverse effects of catechin on the gel properties of myofibrillar proteins.2.Taking catechin-myofibrillar protein mixed system as the research object,study the effect of flaxseed gum on protein structure and cross-linking in mixed system,and determine secondary structure,tryptophan,surface hydrophobicity,solubility,and particle size,zeta potential and electrophoresis.The results showed that the addition of catechin decreased the?-helix content of the protein.After added flaxseed gum,the ?-helix content decreased further,and the ?-sheet,?-turn and random crimp increased to different extents.0.1% flaxseed gum continued to increase the fluorescence intensity,but 0.2% to 0.4% flaxseed gum inhibited theincrease of tryptophan fluorescence intensity induced by catechin;The catechin caused the protein structure to unfold,the surface hydrophobicity increased,and the flaxseed gum caused the surface hydrophobicity to continue to increase;Catechin had no significant effect on protein solubility,but flaxseed gum reduced solubility and protein-water interaction was impaired;After adding flaxseed gum,small particle proteins with a particle diameter of about 10 ?m were protected;The catechin caused an increase in the electrostatic repulsion of the protein,while the flaxseed gum caused the protein-protein to cross-link,and the electrostatic repulsion became smaller;The catechin was covalently cross-linked with the protein,while the low content of flaxseed gum hindered the interaction between the catechin and the protein.The high content of flaxseed gum cross-linked with the protein,and the polymer mainly passed through the disulfide bonds formed.Therefore,the addition of flaxseed gum will further expand the protein structure and cross-linked with proteins.3.The catechin-myofibrillar protein-vegetable oil emulsion system was used as the research object to study the effect of flaxseed gum on the emulsifying properties of the emulsion system and the heat-induced gel properties.Determination of the chemical interaction of catechin-myofibrillar protein solution,zeta potential of emulsion,particle size,rheological properties,emulsifying activity,emulsion stability,gel strength and water retention,and observation of the microstructure of the emulsion by optical microscopy.The results showed that catechin caused a decrease in the content of sulfhydryl groups,and the content of disulfide bonds decreased first and then increased,while flaxseed gum further reduced the content of sulfhydryl groups and increased the content of disulfide bonds.When flaxseed gum is not added,the-OH in tyrosine interacts with the protein to form a hydrogen bond,after adding flaxseed gum,it is converted into a hydrogen bond by interaction with water molecules;Hydrophobic interaction decreased with increasing amount of flaxseed gum;The catechin had no significant effect on the zeta potential,and the flaxseed gum caused the electrostatic repulsion to become smaller;The catechins increased the particle size of the emulsion,and the addition of flaxseed gum moved the particle size distribution toward the small particle size.;The catechins increased the shear stress and viscosity of the emulsion,and the flaxseed gum caused a further increase;the catechin reduced the storage modulus of the gel,and the flaxseed gum increased the storage modulus;The catechin reduced the emulsification activity of the emulsion,the flaxseed gum increased the emulsification activity.The catechins improved the stability of the emulsion.When the flaxseed gum content was 0.1%,the stability of the emulsion was the best,and when it was higher,the stability was deteriorated;The catechins reduced the gel strength and water retention,and the flaxseed gum increased both;Microscopic images showed that when the flaxseed gum content was 0.2%,the droplet diameter was the smallest.Therefore,flaxseed gum can alter the proteinconformation,thereby weakening the adverse effected of catechin on the myofibrillar-vegetable oil emulsion system,especially the gel properties of the heat-induced gel formed by the emulsion. |
PDF Full Text Request