Study On The Preparation Of Bovine Serum Albumin-Dextran Nanoparticles And Encapsulation Of Egg White Peptides

Egg white active peptide is obtained by enzymatic hydrolysis of egg white protein,which has a variety of human metabolism and physiological regulation functions,such as promoting immunity and hormone regulation,as well as antioxidant,bacteriostatic and other functional activities.It is easy to digest and absorb,and extremely safe to eat.However,most active peptides are inactivated by protease cleavage in the small intestine.Nanoparticle carriers prepared with natural biomacromolecular materials can be used to encapsulate,protect and delivery drugs and physiological active components.Bovine serum albumin(BSA)is widely used as a drug carrier because of its advantages of non-antigenicity,degradability and non-toxicity.However,when protein was used as nanoparticle carrier,it has limitations,which is easy to precipitate and flocculate at the isoelectric point.Therefore,dextran can be inserted into protein molecules through the Maillard reaction to change its structure and functional properties,so that the nanoparticle carrier has excellent characteristics.In this study,bovine serum albumin was taken as the research object.Nanoparticles were prepared by Maillard reaction,and egg white peptides were encapsulated to prepare higher encapsulation efficiency and loading capacity.This research will provide technology for the development of new and natural nanoparticles with good functional properties.(1)In this paper,bovine serum albumin and dextran were used for the Maillard reaction to prepare nanoparticles.Particle size and absolute potential were taken as the measurement indexes.Through single factor and orthogonal experiment,the optimal technological conditions for BSA-dextran nanoparticles were determined as follows: the molecular weight of dextran 70 KDa,the volume ratio of dextran to BSA1:4,the concentration of conjugate 4.0mg/mL,and pH 5.5.The nanoparticles were observed by transmission electron microscopy,both nanoparticles were spherical in shape.(2)The structural and functional properties of bovine serum albumin-dextran nanoparticles were determined and characterized.The experimental results showed that the solubility,the surface hydrophobicity and the emulsifying activity and emulsifying stability were significantly improved,indicating that the Maillard reaction significantly improved functional properties of proteins.SDS-PAGE,infrared spectroscopy and fluorescence spectroscopy were used to investigate the structural of protein.SDS-PAGE gel electrophoresis also confirmed that,with the progress of Maillard reaction,dextran was buried into the protein molecules,resulting in a new macromolecules.FT-IR spectra showed that the change of the peaks of amide bonds and enhance of of hydroxyl group and glycosidic bonds,confirmed that the introduction of dextran changed the structure of BSA.Fluorescence spectra showed that the maximum fluorescence intensity of the protein was significantly reduced,fluorescence spectra was shifted to a longer wavelength,the hydrophilic ability of the protein was enhanced by Maillard modification.The nanoparticles were observed by transmission electron microscopy.(3)Egg white peptides were encapsulated with nanoparticles with assistance of ultrasound.Through single factor and orthogonal experiments,we decide the optimu m conditions is the mass ratio of egg white peptides to nanoparticles 1:6,pH 4,and the ultrasonic time 6min,which takes encapsulation efficiency and loading capacity as the measurement indexes.It was found that the egg white peptide nanoparticles had good thermal stability.By comparing the encapsulation efficiency of BSA and BSA-dextran nanoparticles,it was found that there was no appreciable difference between both the encapsulation efficiency of the two type of nanoparticles.Based on these two experiments,it can be seen that the Maillard reaction improved the functional properties of nanoparticles,but has no effect on the encapsulation efficiency.(4)Taking sensory evaluation as the index to optimize the production process of oral liquid,the optimum process conditions were obtained: egg white peptidesnanoparticles addition 1 %,VE addition 0.01 %,potassium sorbate addition 0.02 %,citric acid addition 0.02 %,sodium carboxymethyl cellulose addition 0.02 %,sodium cyclamate addition 0.03 %,potassium sorbate addition 0.03 %,and glycerin addition 0.2 %.To study stability,the Oral liquid was placed at 40±2 ?for 1~7d.The final stability factor is 95.21 %,the oral liquid is transparent and uniform in color,and the taste was sweet and sour,suitable for no odor,no precipitation and delamination.