Effect Of Chemical Modification On The Properties Of Soy Protein Isolate And Egg Yolk

In order to improve the functional properties of proteins,modification is increasingly applied in food industry.Glycosylation and phosphorylation significantly improve the processability of soy protein isolates,but the effects on the digestibility of soy protein isolates are still unclear.At the same time,the research on the chemical modification of egg yolk proteins is still blank.Phosphorylation and succinylation modifications that can be used to optimize protein properties,which have not been applied on egg yolk yet..Therefore,this study selected soybean protein isolate(SPI)and egg yolk protein as the research objects,and used high-performance liquid chromatography,intrinsic fluorescence,circular dichroism analysis and other techniques to analyze the effect of modification on the structural properties and digestibility of SPI molecules.In addition,the effects of phosphorylation and succinylation on the properties of egg yolk were explored.This study has important guiding significance for the innovation and improvement of the application technology of modified proteins.1.With the increasing of phosphorylation degree,phosphorylation increased molecular weight of SPI,decreased hydrophobicity of the surface,indicating that phosphorylated SPI forms aggregates.Compared with SPI,the molecular weight of glycosylated SPI is lower,indicating that glycosylation can effectively inhibit aggregation.2.Phosphorylation reduced the digestibility of SPI.The degrees of digestion of P2-SPI,P3-SPI and P5-SPI decreased by 3.0%,3.9%,and 8.3%,respectively,compared with the control.The transported and absorbed total amino acid content were decreased by 2.65%,7.26%,and 3.92%,respectively.The highest transported and absorbed essential amino acid content was P5-SPI digestion product.The free amino group of glucose glycosylated SPI increased by 2.7% compared to the control SPI and that of dextran glycosylated SPI increased by 13.2%.The transported and absorbed total amino acid content of the two glycosylation SPI digestion products decreased by 0.84% and 2.73%,respectively.3.Phosphorylation and succinylation modification can significantly improve the soluble protein content,emulsion stability,gel strength and water holding ability of egg yolk,and the digestibility of egg yolk was also significantly improved.