J. M. Pollock and W. F. Geddes. Copyright 1960 by the American Association of Cereal Chemists, Inc.
An experimental soy flour, obtained by hammer-milling decorticated soybeans and defatting with cool petroleum ether, proved similar in nitrogen dispersibility and other analytical characteristics to a commercial defatted flour prepared under mild conditions. Controlled heat-treatments (1 hour, 7.9% moisture) at 75 C. or below had no appreciable effect on nitrogen dispersibility; treatment at 100 C. or above substantially reduced nitrogen dispersibility and materially darkened soy flour color. Inclusion of raw soy flour in farinograph doughs at levels of 1-5% imparted to normal and rest-period curves the characteristics of a stronger flour, the effect increasing with the soy flour level. Soy flour heated 1 hour at 100 C. showed this property to a lesser degree. In baking tests employing 1 mg. potassium bromate per 100 g. of flour, 1% raw soy flour somewhat improved the bread, but higher levels decreased loaf volume; heated soy flours were still more injurious, in proportion to their degree of heat-treatment. Heat-treatment raised the water absorption of the soy flours in doughs.