Quantitation of soya protein by enzyme linked immunosorbent assay of its characteristic peptide

Abstract
An enzyme linked immunosorbent assay (ELISA) is described for the quantitative measurement of soya proteins in processed food products. The peptide fragment bearing an antigenicity against anti‐glycinin (soya bean 11S globulin) antibody was purified from the trypsin digests of autoclaved glycinin and used as an indicator antigen for soya proteins. ELISA samples were prepared also by a combination of autoclaving and tryptic digestion. Quantitation of soya proteins by ELISA was found to resist interference by other food materials, and the ELISA signal was independent of soya bean cultivar. The ELISA method was evaluated on pork sausages which were prepared in the laboratory to contain 0 to 20·8% soya protein isolate. With commercial soya protein isolate as reference standard, the results showed that the detected amounts were in quantitative agreement with the added amounts of soya protein isolate.