Among processed soybeans, soybean koji is produced by breeding koji mold on steamed soybeans and used as raw materials for miso and soy sauce. It has been reported that processed soybeans have angiotensin Ⅰ conversion enzyme (ACE) inhibitory activity, an indicator of blood pressure suppressing activity, and DPPH radical scavenging activity, an indicator of antioxidant activity. Therefore, in this report, we produced soybean koji using two kinds of soybeans, Tachinagaha, a cultivar with a medium protein content, and Sachiyutaka, a cultivar with a high protein content. And we compared the effects of soybean varieties on ACE inhibitory activity and DPPH radical scavenging activity of soybean koji were compared. As a result, unexpectedly, the ACE inhibitory activity of soybean koji prepared from Tachinagaha was higher than that of soybean from Sachiyutaka. In addition, the activity of scavenging DPPH radicals of soybean koji made from Sachiyutaka was higher than that of soybean koji from Tachinagaha.
