豆渣爲製造豆漿、豆腐與豆花等黃豆加工製品之副產品，由於其水分相當高（約80%），導致容易腐敗而無法再利用。而以豆渣製成之豆渣納豆其臭味較濃，不亦爲國人所接受。故本研究利用豆渣接種納豆菌後探討減低豆渣納豆產品臭味與保持生理活性功效之方法。研究結果發現，使用傳統平板培養法與化學分析法對於納豆激酶之測定有顯著之相關性；而添加5然糯米粉與5%玉米粉皆可降低臭味，但添加5%糯米粉之產物其納豆激酶活性較添加5%玉米粉者爲高。而隨著添加糯米粉含量之增加（由5%增加至15%），納豆激酶活性並不會改變(28.67-32.60FU/d)（對照組52.30FU/ml），但臭味逐漸降低。因此，結果顯示豆渣中添加15%糯米粉可有效降低豆渣納豆產品之臭味，且維持相當之納豆激酶含量。
Okara or soymilk residue is the by product of soymilk, tofu and touhua. Because the high water content of the okara, it is easily spoilage and not easy to reuse. Since the off flavor of okara natto is very strong, People usually have low willing to eat it. The purpose of this investigation is to find a way to produce a low off flavor and high physiological property okara natto product. The result found there has positive correlation between traditional fibrin plate method and chemical method of nattokinase activity measurement. Both 5% waxy rice flour and 5% corn flour added could decreased the off flavor of okara natto, but the activity of nattokinase of 5% waxy rice added product was higher than the 5% corn flour added product. However, the waxy rice flour added amount increased from 5% to 15% would not significantly change the activity of nattokinase (28.67-32.60FU/ml vs. 52.30FU/ml for control) but decreased the off flavor of okara natto. Therefore, okara 15% waxy rice flour added will significantly decrease the off flavor of okara natto and maintain the activity of nattokinase.
