Utilization by Rats of Protein from a Trypsin-Inhibitor Variant Soybean

Abstract

THE fact that unheated soybean meal is inferior to properly heated soybean meal (SBM) in nutritional quality has been known for more than a half century (Osborne and Mendel, 1917). Trypsin inhibitor in raw soybeans has been proposed to be one of the factors that is responsible for this poor nutritional value (Borchers et al., 1948; Westfall and Hauge, 1948). Recently, Singh, Wilson and Hadley ( 1969), using Polyacrylamide gel electrophoresis, found that commercial soybean varieties had a protein band with 95% relative mobility which corresponds to that of the Kunitz soybean trypsin inhibitor. An experimental variant soybean did not have this band but had a slightly slower moving band with 92% relative mobility. Further study by Clark and Hymowitz (unpublished data) revealed that the trypsin inhibitor obtained was less active than that from the regular commercial varieties. They referred to this variant soybean as 661. This electrophoretical behavior is not unique for 661, since Clark, Mies and Hymowitz (1970), using the same technique as did Singh et al. (1969), found that 20 of 294 varieties of soybean tested had the same electrophoretic band.