The Effect Of Ultrasonic Pretreatment On The Emulsification Properties Of Protein-sugar Complexes

Protein is a kind of biological macromolecule with many functional properties,for a long time,researchers have been devoted to the enhancement of various functional properties,especially emulsification,protein emulsification function is widely used in production,increasing the flavor of food and form a unique texture.Protein modification is an important way to enhance the properties of function,in which ultrasonic modification has the potential to improve protein emulsification by reducing protein volume,increasing surface hydrophobic and molecular mobility,and another important means of modification is to combine sugar into the protein surface through various means to increase hydrophilicity and thus improve emulsification.Ultrasound modification and protein-sugar compounding have greatly expanded the application of protein.In this paper,ultrasound was used to pretreat bovine serum albumin(BSA)and the glycosylation reaction with glucose(Glc),fructose(Fru),and mannose(Man).The effect of ultrasound conditions and the type of monosaccharides on emulsification was studied.;At the same time,the effect of ultrasonic pretreatment on zein nanoparticles(ZNP)formed by antisolvent precipitation of Zein was investigated,and the composite particles which ZNP electrostatically bound with flaxseed gum(FSG),the effect of ultrasound on composite particles and its application in Pickering Emulsion were investigated.The main research is as follows:1.The research selected three kinds of monosaccharides:glucose,fructose,and mannose.The effects of sugar structure differences under ultrasonic treatment on the degree of glycosylation and emulsification of BSA were studied.The results showed the degree of improvement of bovine serum albumin emulsification by the three kinds of monosaccharides was as follows:glucose>mannose>fructose.In terms of ultrasound intensity,high-power ultrasound-treated BSA-sugar complexes had better emulsification activity,stability,and grafting degree;however,low-power,long-term ultrasound was not good for emulsification stability.At the same time,fluorescence emission and infrared spectroscopy confirmed the ability of sonication and glycosylation to modify the conformation of proteins,of which monosaccharides have different effects on the structure of BSA.Finally,from the analysis of glycosylation sites and binding rate,it was further revealed that ultrasound increased the glycosylation sites of the three sugars on BSA to varying degrees,and promoted the degree of glycosylation reaction.The results also found that the degree of molecular weight shift of BSA-sugar complex was closely related to the emulsification result.Studies have shown that ultrasound is a physical method to effectively improve the emulsification of proteins.By expanding the spatial conformation of BSA,hydrophobicity and glycosylation sites were increased.The spatial structure of monosaccharides affected its ability to bind to BSA and determined BSA-Sugar complex surface properties,which in turn affect emulsification.2.Zein was used to construct ZNP with a particle size range of 150?200 nm by ultrasonic-assisted anti-solvent technology,and the effect of ultrasound on the stability of ZNP-FSG composite nanoparticles was studied.Studies have shown that the pretreatment of Zein in ethanol aqueous solution can significantly reduce the particle size of ZNP formed later,and its potential increased accordingly.Under low-power ultrasound,the particle size further decreased with increasing processing time,and the potential improved stability.When the ultrasonic power increases to 460 W/cm~2,the particle size of ZNP started to increase slowly,and the potential also slowly decreased.The results showed that proper ultrasonic intensity can reduce the particle size of the protein and improve its stability in solution.When the ratio of ZNP to FSG was 1:1,the homogeneity promoted the combination of ZNP and FSG through electrostatic interaction and steric hindrance to achieve the strong hydrophobic modification of the ZNP surface.Studies have shown that FSG acts as a multi-layered hydrophilic film on the surface of ZNP particles,which enabled ZNP to be adsorbed on the surface of oil droplets,and effectively resisted the aggregation and rupture of droplets in emulsions.This paper studied the changes of microstructure,droplet size and high temperature stability of emulsion.Due to the thickening and emulsifying properties of flaxseed gum,the physical stability of Pickering emulsions was improved.The emulsion formed by ZNP-FSG after different sonication had higher stability against high temperatures than the blank group.