Study Of Phosphorylation And Succinylation Of Soy Protein Isolate Preparation And Functional Properties

This study focused on the preparation process of phosphorylation and succinylation of soy protein isolate (SPI); the changes of the functional properties of SPI before and after modification. It would be helpful for the optimization of product processing and the proper application of SPI.Succinicanhydride and POCl3 were used to modify the SPI in this paper. Technology was optimized by Central Composite Design theory of Box-Behnkenn. The effects on functional properties of SPI and Phosphorylation and Succinylation of SPI such as aqueous solubility, emulsification properties,foaming properties, gel, water holding capacity and viscosity were researched. The structures of modified SPI were studied by DSC and FTIR. It can reached the following conclusions:1. Based on the solubility index, single factor experiments were done at first toestimate the proper ranges.Technology was optimized by Central Composite Design theory of Box-Behnkenn. The optimum condition phosphorylation of SPI were:added POCl30.095 g per 1g protein,the succinicanhydride to SPI 5.00%, the time of reaction is 27.85 min, pH10.11, the degree of phosphorylation was 1.1273 g/100g protein.2. Based on the solubility index, single factor experiments were done at first toestimate the proper ranges.Technology was optimized by Central Composite Design theory of Box-Behnkenn. The optimum condition succinylation of SPI were:the amount of Succinicanhyd-ride is 0.11g per 1g protein.Succinicanhydride the succinicanhydride to SPI 5.82%, the time of reaction is 29.19 min, pH 8.52, the degree of succinylation was 84.31%.3. The results showed that functional properties of modified SPI changed in different degrees. The isoelectric point of phosphorylation SPI offset from the 4.25 to 3.75. The aqueous solubility of phosphorylation SPI was improved when pH 2.0-3.5 and 4.0-7.0. The emulsification properties, foaming properties, gel, water holding capacity and viscosity were also increased. The isoelectric point of acylation SPI offset from the 4.25 to 3.70. The solubility of acylation protein significantly increased than the original protein higher than the isoelectric point of the region, while the isoelectric point decline in the following regions; acylated SPI significantly increased the emulsifying activity; foaming rate and foam stability, water holding capacity increases; it is not significant change in viscosity an, it is in pH 7.0 and 8.0 can not form a gel.4. The structures of modified SPI were studied by DSC and FTIR. DSC analysis showed that the modified temperature of modified SPI was higher than raw SPI.FTIR spectra showed that SPI were successfully modified by POCl3 and succinic anhydride, though POCl3 and succinic anhydride were induced to protein molecule to alter its structure and to improve their functionalities.