Study On Molecular Modification And Processing Character Of Soy Protein

This paper focused on modifying the soybean 7S globulin through acetylation, PHosPHonation and protease. The functions of them were estimated by the capacity of holding water, emulsification and absorbency of oil. The results indicated that both the modifications of chemistry and enzyme methods could take some meliorations to the function of Soybean 7S globulin. The capacity of holding water and the emulsification stability of soybean 7S globulin could be greatly advanced by appending acid anhydride (15%v/w), the absorbency of oil could be evidently advanced by the accession of STP(l%w/w). The capacity of holding water, emulsification and emulsification stability of soybean 7S globulin modified by pawpaw protease were evidently advanced while the hydrolyze index was 10.78%. Soybean 7S globulin could be hardly advanced by Asl.398 protease.modification research of soybean 7S globulin and soy protein isolate (SPI) hydrolyzed by papain (DH%=3.7% and DH%=8.9%) was made separately using ascorbic acid and sodium alginate. The optimal sample was obtained by adopting five PHysics and chemistry indexes: viscosity, foaming property, foaming stability, emulsifying property, emulsifying stability. The result showed: the soybean 7S globulin and ascorbic acid in a ratio of 5 to 0.3,the SPI(DH%=3.7%) and ascorbic acid 3 to 0.3, the SPI(DH%=8.9%)and ascorbic acid 3 to 0.1, the SPI(DH%=3.7%) and sodium alginate 7 to 0.1,the SPI(DH%=8.9%)and sodium alginate 3 to 0.1 are preferable.the effect of the soy protein modified by ascorbic acid is more notable than by sodium alginate. sodium alginate only promote the foaming stability and emulsifying stability property of the soy protein isolate enzymed(DH%=3.7% and DH%=8.9%), but have the certainly negative action to foaming property.From the economy and appliance angle of the actual production, synthetically evaluating the five preferable samples: the soybean 7S globulin and ascorbic acid in a ratio of 5 to 0.3 is optimal.The effect of three factors, including soaking time, precipitation PH and ice-bathing time, on the yield of soybean US globulin was studied and its mechanism was analyzed. The result of multiple linear regression analysis was: y=0.02738 X ST-0.4875 X PH+0.028893 × IT+3.8617(y: yield; ST: soaking time; PH: precipitation PH 值; IT: ice-bathing time; R2=0.9805) PHosPHated US globulin (11S~P) was prepared by modifying 11S globulin with sodium triPHosPHate (STP). It was validated by Infrared Spectrum Analysis that -PO43- was indeed imported. Compared with soybean protein isolate(SPI), functional properties of both modified and non-modified 11S globulin wereevaluated, including solubility, emulsifying capacity, emulsifying stability and oil-holding capacity. Functional properties of PHosPHated 11S globulin were improved in different extents.