Preparation Of Tamarind Seed Globulin-EGCG Covalent Complex And Its Application In Emulsified Sausage

Tamarind seed globulin(TSG)is a protein extracted from waste material of tamarind seed.Its amino acid pattern matches human needs very well,and it is a relatively high-quality protein.However,TSG has poor functional properties such as emulsification and gelation,which restricts its application in food.Therefore,it needs to be modified to improve its functionality.Recent studies have shown that the covalent interaction between polyphenols and proteins is beneficial to improve the emulsification,gelation and other functional properties of proteins,but the functional changes caused by changes in protein structure under different binding rates are not clear enough.To this end,this article uses alkali treatment to make TSG and epigallocatechin gallate[(-)-epigallocatechin-3-gallate,EGCG]covalently complex to improve the emulsification and gel properties of TSG.Explore the effect of different alkaline treatment reaction conditions on the binding rate of TSG and EGCG.At the same time,the functional changes caused by the changes of TSG structure under different binding rates are analyzed.In order to investigate the practical application effect of the covalent combination of TSG and EGCG,the compound with the best emulsification and gel properties was added to the emulsified sausage.TSG-EGCG covalent complex was prepared with TSG and EGCG as raw materials.Explore the reaction conditions of different alkaline treatments,namely:the mass ratio of TSG to EGCG,the reaction pH,and the effect of reaction temperature on the binding rate.The analysis of the changes in the content of free amino groups and sulfhydryl groups showed that TSG and EGCG covalently complexed with the free amino groups and sulfhydryl groups of TSG mainly through the oxidation of the phenolic hydroxyl groups on the side chain of EGCG.Fourier infrared transform spectroscopy,endogenous fluorescence spectroscopy,and ultraviolet spectroscopy were used to study the structural and functional changes of the prepared TSGs with significantly different binding rates.The results show that EGCG can change the secondary structure of TSG.As the binding rate increases,the content of α-helical structure of TSG decreases significantly(P<0.05),and the content of β-sheet structure increases significantly(P<0.05).Level institutions gradually stretched out.And EGCG can change the tertiary structure of TSG,the aromatic amino acid residues change from a hydrophobic environment to a hydrophilic environment,and the peptide chain becomes more stretched.The results of TSG functional changes under different binding rates show that as the binding rate increases,the emulsification and gel properties of TSG are improved to varying degrees,and when the binding rate is 76.89%,the emulsification and gel properties of TSG are improved.The effect is most obvious(P<0.05).In order to investigate the practical application effect after the covalent combination of TSG and EGCG,a compound with a binding rate of 78.69%with good emulsification and gel properties was added to the emulsified sausage.TSG was used as a control to study the effect of the added amount on the quality of the emulsified sausage.influences.The experimental results show that when the addition amount of TSG and TSG-complex is 2%,the cooking loss,water retention property and taste of emulsified sausage are significantly improved(P<0.05),and all the indicators of the compound group are excellent.For adding the TSG group.Adding more than 2%will adversely affect the color of the emulsified sausage.With the increase of the added amount,the pH of the emulsified sausage did not change significantly.Scanning electron microscopy results show that adding TSG and the compound will make the microstructure of the emulsified sausage more compact,and the three-dimensional gel network of the emulsified sausage with the compound will be more uniform and clear.In summary,the quality of emulsified sausages is significantly improved when the addition amount of TSG and the compound is 2%.Since the modified TSG has good emulsification and gel properties,the improvement effect is better.