Abstract: sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) was used for the qualitative and quantitative analysis of soybean protein isolate (SPI) in emulsion-type pork sausages. Results showed that SPI displayed five major bands including β-conglycinin d1, α', β and d2 subunits and glycinin d3 subunit in SDS-PAGE, which could be distinguished from pork protein. A linear regression equation with band intensity as a function of SPI concentration of α' subunit in the range of 0.5%－10% was obtained for determining SPI in emulsion-type pork sausages. The prediction values of samples containing SPI at various amounts of 7%, 3%, 1.5%, 0.8% and 0.5% exhibited a high reproducibility with variation coefficients between 1.90% and 7.01%. The successful application of SDS-PAGE was also demonstrated by a high correlation coefficient of 0.98 obtained from regression analysis between the predicted and actual values of SPI in spiked emulsion-type pork sausages.

Key words: emulsion-type pork sausages, soybean protein isolate, determination, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE)