Study On The Preparation And Performance Application Of Products Based On The Interaction Between Casein And Polysaccharides

Casein is an animal protein with rich nutritional value,good biocompatibility,biodegradability and other advantages.It is widely used in food and other fields,especially in the field of food colloids,which has huge application prospects.Because casein has defects such as low water solubility,narrow p H tolerance range,and micelle reaggregation,this limits its application range in the delivery of food active substances.In this paper,casein was used as a matrix,and protein-polysaccharide covalent interactions and physical electrostatic interactions were used to prepare two casein-based functionalized products with improved performance.They were used in oil-in-water emulsions and curcumin delivery.Use covalent interaction to prepare casein-soluble soybean polysaccharide cross-linked product,explore its structure,emulsification and solubility and other physical and chemical properties,and make preliminary application of emulsion.Using physical electrostatic interactions,casein was blended with pectin with different esterification degrees,and a soluble complex was prepared by acid titration.The degree of pectin esterification and the mass of proteoglycan were compared to the phase of the composite system.At the same time,molecular dynamics simulation is used to analyze the force and stability of the composite system,and it is initially applied to the construction of the curcumin delivery system to explore the structural characteristics and release of curcumin under the optimal reaction conditions of casein and pectin.Characteristics and in vitro digestion characteristics.The main conclusions are as follows:(1)Transglutaminase is used to catalyze the glycosylation reaction of casein and soluble soybean polysaccharides,through the determination of various physical and chemical indicators,sodium lauryl sulfate-polyacrylamide gel electrophoresis analysis,Fourier transform infrared spectroscopy analysis,endogenous fluorescence spectrum analysis and scanning electron microscope observation,to study the changes in the physical and chemical properties and structural properties of the cross-linked products.The results showed that when the mass ratio of casein to soluble soybean polysaccharide was 1:1 and the amount of transglutaminase added was 5 U/g,the degree of glycosylation reaction was higher,and the browning index was 0.542 and the intermediate product content was 0.907,the grafting degree reached 19.9%;the physical and chemical properties of the cross-linked product were improved compared with single casein,the solubility increased from 47.2%to 67.0%,the emulsification activity increased from 116 m~2/g to 123 m~2/g,and the emulsification stability Increase from 16.9 min to 37.6 min;sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Fourier transform infrared spectroscopy results show that soluble soybean polysaccharides are successfully grafted on casein;endogenous fluorescence spectroscopy results show cross-linking reaction The degree of protein structure changes in the cross-linked product;scanning electron microscope observation results show that the cross-linked product presents a heterogeneous,loose and porous mixed network structure;the casein-soluble soybean polysaccharide cross-linked product is used to prepare an oil-in-water emulsion,The physical stability test results show that the cross-linked product emulsion droplets have higher surface charge and stronger steric hindrance than single casein emulsion droplets,so it can resist different environmental factors.(2)The physicochemical properties and mechanism of action based on the electrostatic complexes of casein and pectin.Use turbidity andζ-potential to express the effect of pectin esterification degree,p H and protein-polysaccharide mass ratio on the composite state,and analyze the forces of the two through molecular dynamics simulation,use solubility measurement,infrared spectroscopy and fluorescence spectroscopy Explore the changes in the physical and chemical properties and structural properties of the proteoglycan complex system.The results show that after adding pectin to casein,the turbidity distribution curve tilts to the left,which effectively reduces the accumulation of casein at the isoelectric point.The compound of casein and MP67%maximizes the increase in casein at the isoelectric point.Solubility increased from 4.18%to31.8%;when casein is complexed with MP67%,MP47%,MP41%and MP36%,it reaches OD at 5:1,4:1,4:1 and 4:1,respectively Peak;the results of fluorescence spectroscopy and infrared show that the two interact.The fluorescence intensity of the composite system gradually decreases with the decrease of p H,and the peak wavelength appears slightly blue shift(1～5 nm);the results of molecular dynamics simulation show,The electrostatic interaction force dominates the combination between casein and pectin.The electrostatic effect of the casein-MP67%system is stronger than that of the casein-MP36%composite system,and the casein-MP67%composite system is more stable.(3)This study systematically explores the potential of casein and MP67%(5:1)to form a soluble complex under acidic(p H 5.0)and neutral(p H 7.0)conditions as a delivery carrier for curcumin,which is released and simulated in vitro Digestion in vitro reflects the release performance of curcumin and changes in bioavailability in vivo.Differential scanning calorimetry and thermal stability analysis analyze the thermal properties of the complex.Infrared spectroscopy,fluorescence spectroscopy and scanning electron microscopy explore casein-curcumin-fruit The structural properties of the glue compound.The results show that when the p H is 5,the load rate of curcumin is 96.0%at the maximum,and the load capacity reaches 4.80μg/mg;the stability is improved,and the release rate after 24 h is only 34.3%;the thermal stability increases,The highest retention rate after heating for 3 hours is 58.3%,and the peak temperature of protein heat flow increases from 117℃to 138℃;the bioavailability of curcumin is significantly increased from 31.6%to 79.1%,which can significantly reduce the degradation of curcumin Speed;infrared and fluorescence spectroscopy results show that casein-curcumin-pectin forms a soluble complex at p H 5.0;scanning electron microscopy results show that the surface of complex-III is continuous,without cracks,pores or breaks,and is more compact The raised structure.