Studies On Optical Properties And Applications Of Soybean Protein Gels

The thesis is based on theories of molecular biology , vegetable protein technology, food physics, biochemistry , organic chemistry, physical chemistry, electricity, transmit heat, high molecular materials science and modern instrument analysis .Optic properties of soy protein transparent gel are proposed and studied for the first time .The main factors which affect soy protein forming transparent gel are analyzed .The relationships between molecular forces and the transparency of soy protein gel are studied. After molecular structure and microstructure of soy protein transparent gels being studied thoroughly, molecular model of "even distributed" is creatively put forward for the first time. Mechanical models and equations of soy protein transparent gels are founded . Based on these, high molecular transparent materials of biodegradable plastics making from soy protein are manufactured for the first time.The transparent mechanisms of soy protein gels are firstly explored in this thesis .The relationships among pH values heating temperatures, heating times, protein concentrations and transparency as well rheology properties of SP1 gels are analyzed and studied .Affects of these factors on transparency and rheology properties of soy 7S globulin gels are further studied .Mechanisms of solvents (alcohol and glycerin), BSA , FAS , NaCl and sulfhydryl group reagents as well their concentration which affect gel optic properties and gel strength of SPI and soy 7S globulins have been studied. These results prove that hydrogen bonds , ionic bonds, hydrophobic bonds and disulfide linkages have more important affection on gel optic properties and gel strength of SPI and soy 7S globulins. With actions of hydrogen bonds being strengthened, these advantageously improve gel transparency and strength of soy proteins. With actions of ionic bonds being strengthened, these advantageously improve gel strength of soy proteins. Although reinforcement of hydrophobic actions improves gel strength of soy protein, it also affects solubility of soy proteins, therefore transparency of soy protein gels is decreased. The forming of disulfide linkages increase gel strength of soy proteins, but gel transparency of soy protein gels is decreased. Based on these experimental results, mechanism model of soy 7S globulins gelation on FAS action condition is put forward for the first time.Through amino acid analyzing, composition of soy protein amino acids of affecting protein gels transparency and strength is analyzed. Through hydrophobic actions of soy protein molecule surface are determined by fluorescence spectrometric method ,the relationships between hydrophobic action of soy protein molecule surface and protein gelation are studied . Differences of soy protein and their main fraction subunits are studied by SDS-PAGE and changes of subunits during forming transparent gels are analyzed.Microstructures of SPI, soy 11S globulins and soy 7S globulins are observed by SEM. Fourier transformed infrared spectroscope (FTIR) measurements are performed to study the secondary structures of SPI, soy 11S globulins and soy 7S globulins molecule. The experimental results have shown that the gelation mechanisms of soy 7S globulins differ from these of SPI and soy 11S globulins. Transparent soy protein gels have highly ordered structures.Based on electro-characteristic and double electric layers models, directional mechanisms ofsoy protein molecular are analyzed for the first time on DC heating condition. After the main factors which effect soy protein gels transparency and strength being studied on DC heating condition ,the different affects on soy protein gels transparency and strength by DC heating and water bath heating are analyzed and compared ,and the transparent mechanisms of soy protein gels are further explored .In addition to temperature action as water bath heating ,DC heating is added as electric field directional action .As a results , heating rate is increased. Directional range degrees of soy protein molecules are raised. These...