Preparation And Characterization Of Rice Residue Protein Films

Rice residue is the by-products of rice processing which has balance of amino acid and hypoallergenic.In this dissertation,food grade rice residue protein powder was used as raw material to optimize the preparation process of RRP film.The effects of ferulic acid modification and polysaccharide complex on film performance and structure were investigated.The main results were as follows:(1)Through optimizing single factor experiments and response surface experimental design,the optimal conditions for the formation of rice residue protein films were obtained:protein concentration 4.46%,glycerol concentration 2.52%,NaOH concentration 0.081mol/L and reaction temperature 75 ?,Under these conditions,the tensile strength,elongation breaking,water vapor permeability and water solubility reached 1.85 MPa,37.8%,8.24 g·mm/KPa·d·m2 and 46.5%respectively.(2)With the content of 0.1%(W/V)ferulic acid,the tensile strength,the water vapor permeability and the water solubility of the modified RRP film were increased by 20.33%,20.58%and 23.88%.Results of FTIR showed that the amide band absorption peak red-shifted,P-sheet was transformed into a flexible random helical molecular structure,and the secondary structure of the protein was changed by ferulic acid cross linking.DSC analysis showed that the modification enhanced the intermolecular interaction,increased the glass transition temperature of the film,and the film indicated better thermal stability.XRD analysis showed that modified protein covalent cross-linking occurred between molecules,and the film crystallinity was increased.SEM results displayed the microstructure of the film was improved to be smoother and uniformed.The modified rice residue protein film with ferulic acid indicated better performance and more stable spatial structure.(3)Using chitosan,carboxymethyl cellulose,soluble starch to compound with rice residue protein film,the results indicated that the rice residue protein-chitosan composite film moldability was better.When the ratio of rice residue to chitosan is 6:4,the tensile strength of the composite films reached 10.34 MPa which was 3.45 times higher than the single RRP film,and the water vapor permeability is 4.19 g·mm/KPa d·m2,water-soluble is 26.64%.The results of FTIR showed that the complex absorption peaks were red-shifted due to the intermolecular electrostatic interaction and hydrogen bonding interaction.DSC analysis showed that polar groups were introduced into the rice slag protein to make the glass transition.XRD analysis showed that the interaction between rice residue protein and chitosan destroyed the crystal structure of the two substances,and the diffraction peak intensity and crystallinity of the film changed.SEM results displayed a good compatibility between polysaccharide and protein,the composite formed a uniform and stable network structure,the film surface structure become more smooth and uniform.