Comparison of nutritional and antinutritional factors in soybean and fababean seeds with or without cortex

The composition and contents of nutritional factors such as proteins, lipid s, carbohydrates, fibers, amino acids, and antinutritional factors such as trypsin inhibitors, phytic acid, and tannins were compared in soybean and f ababean seeds with emphasis placed on the nutritional improvement of the se eds by cortex removal. Protein hydrolysis analysis for both whole seeds and seed with cortex removed revealed the presence of a large amount of lysine , arginine, aspartic acid, glutamic acid, glycine, and leucine while these seeds contained a low level of tryptophan, cystine, and methionine. Some an tinutritional factors such as trypsin inhibitors, phytic acid, and tannins were detected in soybean and fababean seeds: phytic acid content and trypsi n inhibitor activity were higher in soybean seeds than in fababean seeds wh ile the difference in the tannin content was less pronounced. It was found that most of the tannins occurred in the cortex of the soybean and fababean seeds. Tannins are pholyphenolic compounds that readily form indigestible complexes with proteins and other macromolecules under specific environment al conditions. By removal of the cortex, tannins were almost completely eli minated without changes in the protein composition and amino acids. From th ese results, it is assumed that since soybean and fababean seeds contained a high concentration of antinutritional factors in the cortex such as tanni ns, the utilization of the legume seeds after removal of all of the cortex is suitable for human diet or industrial products.