Effects Of High-pressure Carbon Dioxide And High-pressure Homogenization Synergistic Technology On The Physicochemical And Functional Properties Of Bovine Serum Albumin

With the development of non-thermal sterilization technology for foods,the use of a variety of non-thermal technologies has also emerged.The combination of high pressure carbon dioxide and high pressure homogenization results in a better bactericidal effect at lower homogenization pressures.However,there is a little research on whether the combined technologies have bactericidal effects and whether it affects other components in the food.Therefore,we have selected the high-pressure carbon dioxide and high-pressure homogenization synergistic technology to study the effects of macromolecular protein structure and functional properties.Milk is one of the world's most sold and most easily accepted beverages.Homogenization and sterilization are essential in the production of fresh milk from processed milk.In this study,serum proteins in milk were selected as model proteins,and the changes in protein structure were analyzed by UV-visible spectrometry,fluorescence spectroscopy,circular dichroism,fluorescence probe method and Ellman's methods.At the same time,the foaming properties of proteins were observed.Changes in functional properties such as emulsifying properties and thermal stability were investigated.The aim is to provide experimental data and theoretical basis for the application of high-pressure carbon dioxide and high-pressure homogenization synergistic technology in the food industry,and hope to promote the development of a variety of non-thermal technology.The main research contents of the thesis are as follows:(1)Review the principle of non-thermal sterilization technology and introduce high-pressure homogenization technology and high-pressure carbon dioxide technology in detail;introduce the structural characteristics of protein and maintain the interaction of stable structure,and briefly introduce the situation of bovine serum protein(BSA)The common analytical methods for studying structural changes and functional changes of proteins were introduced.Finally,the research progress of multitechnology combination was summarized.(2)Detailed analysis of the functional properties of BSA,foaming and foaming stability,emulsification and emulsion stability,thermal stability.The results showed that under the condition of high pressure homogenization,the foaming,emulsifying and thermal stability of the protein were improved to some extent,and under the lower homogenization pressure,the functional improvement effect was more obvious.When a certain homogenization pressure is exceeded,the functionality will have a decreasing trend;after the addition of carbon dioxide,the foaming and emulsifying properties will decrease due to the change of p H,but the thermal stability is not affected.(3)In this chapter,we used UV-Vis spectrometry,fluorescence spectroscopy,circular dichroism,fluorescent probe method and Ellman's method for protein secondary and tertiary structure,surface hydrophobicity,disulfide bond and sulfhydryl group.The change in content was analyzed.The results showed that under the condition of high pressure homogenization alone,the partial hydrophobic amino acid residues of the protein were masked from the exposed state to the aggregation state of the protein during the process of increasing the homogenization pressure,and the percentage of ?-helix decreased.0.4%,the surface hydrophobicity decreased from 242.18 to 206.29.The content of disulfide bonds and the number of sulfhydryl groups will be minimized at 40 MPa,and then increase with increasing homogenization pressure;after the addition of carbon dioxide synergy,more amino acid residues will be exposed,and overall will become loose.The percentage of ?-helix,surface hydrophobicity,sulfhydryl groups and disulfide bonds all have a tendency to decrease first and then increase,but will eventually be lower than the blank control sample.