EFFECT OF THERMAL AND PROTEOLYTIC PROCESSING ON GLYCININ, THE 11S GLOBULIN OF SOY (GLYCINE-MAX) - A STUDY UTILIZING MONOCLONAL AND POLYCLONAL ANTIBODIES

Glycinin-specific monoclonal antibody (Mab) IFRN 0025 and polyclonal anti-glycinin antiserum have been used in various enzyme-linked immunosorbent assay (ELISA) formats to follow the immunoreactivity of purified glycinin during thermal and proteolytic treatments. Glycinin T, a well-defined stable intermediate of glycinin trypsinolysis, exhibited 10 times the immunoreactivity of the native globulin with IFRN 0025, where as more rigorous proteolysis destroyed Mab recognition entirely. Heating glycinin to 80-degrees-C has no effect on immunoreactivity as determined by a two-site ELISA; when glycinin was heated further, recognition declined by about 50%. At temperatures above 92-degrees-C reactivity increased sharply. The two-site ELISA was also used to determine glycinin immunoreactivity in a range of industrially processed soy flours and concentrates. Defatting substantially reduced glycinin immunoreactivity, suggesting this widely used procedure significantly affects glycinin conformation. In general, immunoreactivity was reduced by heat and/or protease processing, although several samples showed enhanced immunoreactivity. Furthermore, flour samples allegedly subjected to the same processing regime displayed markedly different immunoreactivities. Our data also demonstrated how ELISA format can influence detectable immunoreactivity; some flours with very high reactivities in the two-site ELISA display no activity in a direct ELISA. The data presented are discussed in view of the need for quality control of soy processing and the possibilities offered by immunological techniques.