The Study Of Industrial Technology Of Preparing 7S-Rich And 11S-Rich Soybean Protein Isolate

Soy protein isolates was mostly used as food ingredient to improve food textural and nutritional properties. 7S and 11S globlines are the major components of SPI, 7S is glycoprotein and have good solubility and emulsified ability, 11S have good gel ability and foaming ability, the ratio of 7S and 11S has important effects on the properties of SPI. In order to meet the requirement of SPI of various functional properties, the objectives of this study were to investigate the industrial technology of preparing 7S-Rich SPI and 11 S-Rich SPI and develop the specific SPI with high functional properties.This study, the ultracentrifugation analysis method was used to investigate the size distribution of protein particles in soymilk prepared from different extracting method, the particles were fractioned as soluble fraction(diameter<50nm) and protein particle fraction(diameter>50nm). The results showed that under neutral extraction condition, adjusted the pH< 7.0 and low ionic strength, the protein particles in soy protein milk contained more 1S and the soluble fraction contained more 7S. According to this result, we lowed the seperation condition and developed the industrial technology of preparing 7S-Rich SPI and 11S-Rich SPI. The results of SDS-PAGE showed that 7S-Rich SPI contained 7S about 65% and 11S-Rich SPI contained 11S more than 86%.The further study were carried out to investigate the physicochemical and functional properties of 7S-R SPI and 11S-R SPI, the results indicated that 7S-R SPI and 11S-R SPI showed higher quality and functional properties, such as, solubility, disperse stability, water-holding ability, oil-binding ability, emulsification and emulsifing stability compared with commercial SPI. The gel properties and foaming ability of 7S-R SPI and 11S-R SPI showed that various SPI products with different gel properties and foaming ability can be obtained by altering the ratio of 7S-R SPI and 11S-R SPI.7S-R and 11S-R SPI were added in ice-cream and dough prepartion, the results showed that 11S-R SPI increased the volume of ice-cream and the farinaceous value of dough.