Forming And Functional Properties Of Soybean Protein-polysaccharides Conjugations

In this thesis, the soybean poretin isolate(SPI), chitosan(CHI) and sodium alginate(SA) were used as the main materials, to prepare soybean protein-polysaccharide conjugations by the dry-heat reaction. The solubility, emulsifying ability, emulsion stability, foamability, thermal stability and oxidation resistance of the conjugations also were studied in this paper.Firstly the preparation of soybean protein-polysaccharide conjugations was studied. In single afctor experiments, the effects of reaction time, reaction temperature and addition amount of polysaccharide were studied. On the basis of single afcter experiments, response sulface methodology was used to optimize the process conditions. The optimum conditions for the preparation of soybean protein-chitosan conjugations were:reaction time 10.4h, reaction temperature 41.2℃, CHI 25.7% according to the emulsifying ability of the conjugation; and reaction time 9.6h, reaction temperature 38.3℃, CHI 26.1% according to the emulsion stability of the conjugation. The optimum conditions for the preparation of soybean protein-sodium alginate conjugations were:reaction time 10.4h, reaction temperature 43.8℃, SA 33.4% according to the emulsifying ability of the conjugation; and reaction time 7.6h, reaction temperature 43.3℃, SA 33.4% according to emulsion stability of the conjugation.The functional properties of soybean protein-polysaccharide conjugations prepared at the optimum conditions were studied. The result showed that the solubility, emulsifying ability, emulsion stability, thermal stabilityand, foamability of soybean protein-polysaccharide conjugations were all improved in comparison with soybean protein.According to the analysis of SDS-PAGE, new bands was found at the borderline between separation gel and stacking gel. It was because the molecular weight increased after the crosslink reaction between soybean protein and polysaccharide. The moleculars structure features of conjugate were analyzed through IR-spectrums.Considering the functional properties, soybean protein-polysaccharide conjugations were used as egg replacer in cakes to replace about 20% egg, the cakes produced with less cholesterol show better quality than traditional cakes. They were also used in emulsified comminuted meat product, in order to obtain a higher cook yield and an improved texture property.