Studies on the Digestion of Soybeans

Publisher Website
Google Scholar
Abstract
Protein digestibility of properly heated soybeans was significantly higher than of raw and overheated soybeans. Availability values of 5 essential amino acids, as determined by the fecal analysis method, were significantly higher for heated soybeans. Using rats trained for spaced-feeding, it was established that the rate of food passage through the stomach was considerably slower for raw soybeans. Fractionation of intestinal contents in insoluble residue, trichloroacetic acid (TCA)-soluble and TCA-precipitable nitrogen, revealed that insoluble residue and TCA-precipitable nitrogen were always higher in the case of raw soybean feeding. Using a diet containing a complete amino acid mixture to which a crude preparation of the water-soluble trypsin inhibitor factor (TIF) was added, the addition of raw TIF resulted in a slower rate of stomach emptying. The insoluble intestinal nitrogen and TCA-precipitable nitrogen fraction were significantly higher when the amino acid diet was supplemented with raw TIF. The addition of TIF also interfered with the amino acid absorption through the intestinal wall.