Ultrasonic Effect Of Ultrahigh Pressure Treatment On The Structure And Functional Characteristics Of Sporamin With Different Selenium Enrichment Concentrations

As a large country of sweet potato production and consumption,as well as a large country of selenium deficiency,China vigorously develops the selenium rich sweet potato industry,which can not only enable the selenium deficient population to carry out targeted selenium supplementation,but also increase the added value of the sweet potato industry.Today,people increasingly pursue a healthy diet,it has a very large market prospect.The protein content in sweet potato accounts for about 5%-10% of its total weight.Sweet potato protein is mainly composed of sweet potato storage protein Sporamin and sweet potato glycoprotein.Among them,the content of sweet potato storage protein Sporamin accounts for about 90%.With the rapid development of food related technology,protein,as a common food additive,is often added to food for modification.Spray drying and freeze-drying are common protein drying techniques.At the same time,ultra-high pressure processing is also a new means of protein processing and modification.Molecular dynamics technology is now a cutting-edge simulation method,using computer means to simulate the results of experiments.1.Two drying methods,freeze-drying and spray drying,were used to treat sweet potato storage protein Sporamin.The apparent kinetic diameter and zeta potential value of protein by freeze-drying and spray drying under different drying conditions were compared.It was found that the particle size obtained by freeze-drying was smaller,the absolute value of potential value was higher,and the stability in the dispersion system was better.Compared with the surface hydrophobicity of the two drying methods,spray drying has greater damage to the protein structure,and the hydrophobic groups inside the protein are more exposed on the protein surface,making the surface hydrophobicity of better.The emulsifying property of protein obtained by freeze-drying is better than that of spray drying.Circular dichroism analysis revealed that the content of Sporamin protein prepared by spray drying β-The rotation angle and irregular curl were significantly higher than those of freeze-drying.It was found by X-ray diffraction that the protein prepared by the two methods was irregular crystal powder.On the whole,the properties of protein prepared by freeze-drying are better than those of spray drying.2.When different ultra-high pressures(100 MPa,200 MPa,400MPa)were used to treat sweet potato storage protein Sporamin,the protein content showed a trend of first increasing and then decreasing,and the protein content reached the maximum at200 MPa.With the increase of pressure,the particle size of sweet potato protein increases with the increase of pressure,and reaches the maximum at 400 MPa,while the absolute value of zeta potential is smaller at 400 MPa.With the increase of ultra-high pressure,the number of free sulfhydryl groups of protein increased first and then decreased.In the non selenium enriched group,the maximum value was 30.77 at200 MPa;In the selenium rich group,the number of free sulfhydryl groups also reached the maximum at 200 MPa,which was 30.13.The surface hydrophobicity first decreased and then increased with the increase of pressure.The surface hydrophobicity of selenium rich group and non selenium rich group reached the minimum at 200 MPa,which were 258 and 225,respectively.When the pressure rises to 400 k Pa,the surface hydrophobicity continues to rise.Through infrared chromatography analysis,it was found that the effect of pressurization on it was negligible,and through circular dichroism analysis,it was found that irregular curl and β-With the increase of pressure,the rotation angles increased first and then decreased,and reached the maximum at 200 MPa.As the pressure increases gradually,its emulsifying property shows a trend of increasing first and then decreasing.The emulsion has better emulsifying property at 200 MPa,but when the pressure continues to increase to 400 MPa,the emulsifying function of the emulsion decreases.On the whole,proper ultra-high pressure treatment can reasonably modify the protein,improve its surface hydrophobicity and emulsification index.3.Computer simulation was used to simulate the effects of spray drying and freeze-drying methods on sweet potato storage proteins.The results showed that the root mean square deviation(RMSD)and reference conformation structure deviation(RMSF)of spray drying treatment were greater than those of freeze-drying treatment group.It can be mutually confirmed with the previous experimental data.Through computer simulation to simulate the effect of different ultra-high pressure conditions(100MPa,200 MPa,400MPa)on sweet potato storage protein,the result is that the RMSD of sporamina under 200 MPa is the largest,which can be compared with the experiment.It is found that the structure of sporamina is more compact and stable at low selenium concentration,which is consistent with the experimental results in Chapter II.