The Determination Of Soy Protein In Foods By SDS-PAGE And HPLC

An analysis method for soy protein isolate was established by SDS-poly acrymide gelelectrophoresis in wheat flour product. The conditions of the electrophoresis were established:12%separation gel, samples injection of20μL, the voltage of120V; the regression equationwas Y＝1.7867X＋2.0742, and the correlation coefficient was0.9911with the relativestandard deviations (RSD)6.57%; the conditions of SDS-poly acrymide gel electrophoresis inmilk were established: removing fat with acetone,12%separation gel, samples injection of30μL, the voltage of120V; the regression equation was Y=27.913X＋7.5036, and thecorrelation coefficient was0.9922with the relative standard deviations (RSD)7.06%; Theconditions of SDS-poly acrymide gel electrophoresis in sausage were established: removingfat with acetone,12%separation gel, samples injection of20μL, the voltage of100V; Theregression equation was Y＝2.7609X-0.3838, and the correlation coefficient was0.9941withthe relative standard deviations (RSD)6.85%.Another method for analysis of soy protein isolate was established by high performanceliquid chromatography in flour product. The optimum chromatograph parameters were asfollows: the sample was extracted by water with25%acetonitrile, ion pairing reagent aceticacid, detector wavelength at254nm, column temperature45℃. The recoveries were96.20%and the RSD was2.57%, the equation of regression was Y＝5433.8X-3537.1, and thecorrelation coefficient was0.9984, limit of detection（3S/N）was0.38%（w/w）, limit ofquantitation (10S/N) was1.29%（w/w）; The optimum chromatograph parameters in milkwereas follows: the sample was extracted by Phosphate buffe（rpH9.0）, detector wavelength at254nm,column temperature45℃. The gradient:1%-42%B in12min and42%-100%in1min.recoveries were99.30%and the RSD was2.04%, the equation of regression wasY=1E+06X-7068.8, and the correlation coefficient was0.9998, limit of detection（3S/N）was0.3144mg/mL, limit of quantitation(10S/N) was1.0479mg/mL; the optimum chromatographparameters in sausage were as follows: the sample was extracted by carbonate buffe（rpH9.6）,detector wavelength at254nm, column temperature45℃. The gradient:5%–25%B,25–42%B,and42%–50%B. Recoveries were97.90%and the RSD was2.47%, the equation ofregression was Y=2923.1X-970.85, and the correlation coefficient was0.9942, limit ofdetection（3S/N）was0.33%（w/w）, limit of quantitation(10S/N) was1.10%（w/w）.