The Relationship Between Solubility And Structural Of Low Degree Of Hydrolysis's Rice Protein

In this paper, rice protein was treated with alkaline protease to get desired degree of hydrolysis(DH)(0%?1%?2%?3%?4%?5%). The solubility, protein structure and soluble protein which was produced in the process of hydrolysis were analyzed. The research results mainly include the following aspects:(1) The enzymatic hydrolysis conditions of alkaline protease were optimized. The rice protein with low hydrolysis degree was prepared and these proteins' solubility were determined. These results showed that the solubility of rice protein hydrolysates decreased firstly, and then increased in the range of p H 2.0-11.0. Under the same p H, solubility increased with the increase of hydrolysis degree. When p H was 2.0 and the degree of hydrolysis was 5%, a maximum protein solubility was 65.93%.(2) In order to study the influence of different degree of hydrolysis on the rice protein solubility, the change of the disulfide bond content, surface hydrophobicity, surface microscopic structure and molecular weight and the tertiary structure of the different degrees of hydrolysis protein were measured. It showed that with the increase of the degree of hydrolysis, rice protein's molecular weight and disulphide bond content decreased significantly. From the scanning microscopy analysis: the grain size of no hydrolysis rice protein was uneven and the material quality was hard. The size of rice protein hydrolysates was relatively uniform and the surface had more holes and they were fluffier. Results of infrared and fluorescence showed that protein tertiary structure had changed and depolymerization and unfolding of protein occured hydrophilic group exposuring to enhance protein solubility. These structural changes may increased protein solubility.(3) The soluble protein produced in the process of hydrolysis were studied. Peptide content,amino acids content,microstructure,the tertiary structure, the liquid phase of the different degrees of hydrolysis protein supernatant were measured. These results showed that peptide content increased, the content of hydrophobic amino acids gradually reduced with the hydrolysis degree increased. From the scanning microscopy analysis: with the hydrolysis degree increased, network structure of the protein sample was damaged and plated shaped, infrared results showed that the enzymolysis make protein molecules unfold, protein depolymerization occured, liquid phase showed that small molecular peptide of supernatant fluid medium increased with increase of hydrolysis degree, and improved the protein solubility.