Acceleration of Sterol Excretion, Little Meteorism, and Less Inhibition of Iron Absorption by Okara Koji, a New Foodstuff, in Rats

Okara Koji (OK) is the term for okara fermented by Aspergillus oryzae (a fungus for making Miso Koji). The amount of sterol excreted in the feces from rats fed with OK as the dietary fiber (OF) source was greater than that from rats fed with okara (OC, the insoluble residue of homogenized soybean) as the DF source. The digestive residue of OK's insoluble dietary fiber (IDF) was more porous than that of OC-IOF. The stronger sterol excretion with OK would have arisen from the complementary action of OK-IDF hemicellulose and the porosity of the OK-IDF digestive residue. Their complementary action would contribute to the cholesterol-lowering action of OK. The levels of raffinose and stachyose in the OK diet were lower than those in the OC diet. The intake and utilization of soluble dietary fiber and insoluble dietary fiber by the OK diet group were lower than those by the OC diet group. OK would not be a cause of meteorism. Iron absorption with the OK diet was greater than that with the OC diet, and there may have been little inhibition of iron absorption by phytic acid in the OK diet. These results suggest that OK would be a useful food material as a DF source.