Studies on the nattokinase activity and the isoflavone content of steamed soybean fermented by Bacillus spp. during fermentation

• Main Authors: Chun-Ting Chen, 陳君婷
• Other Authors: Tong-Rong Chen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/86635966201643548601

碩士 === 國立嘉義大學 === 食品科學系研究所 === 94 === There are plenty of isoflavones in soybean, isoflavone aglycones are thought to be the most bioactive isomers among the isoflavones. There are still high contents in the fermented soybean foods. This study used four Bacillus subtilis strains from Food Industry Research and Development Institute, Bacillus subtilis BCRC 14714, Bacillus subtilis BCRC 14715, Bacillus subtilis BCRC 14716 and Bacillus subtilis BCRC 14718, and four Bacillus spp. isolated from commercial natto products, brand A, B, C, and D to ferment steamed soybean. We investigated the effects of fermented temperature, time, inoculum size, and addition of carbon source and nitrogen source on isoflavone contents and nattokinase activity during fermentation. The results show that steamed soybeans fermented by Bacillus subtilis strains from Food Industry Research and Development Institute had lower nattokinase activity than steamed soybeans fermented by Bacillus spp. isolated from commercial natto products. But the isoflavone contents were in the contrast, the most aglycones was achieved 114.33 mg/100 g from the steamed soybeans fermented by Bacillus subtilis BCRC 14718 had, the contents was 12.8 times of soybeans. And the nattokinase activity was the lowest, only 5.7 FU/g. The optimal condition for cultivation of solid state fermentation for Bacillus subtilis was fermented the steamed soybeans by Bacillus subtilis BCRC 14718 at 45℃ for 48 hrs, the aglycones was achieved 165.79 mg/100 g, the contents was 18.6 times of soybeans. The nattokinase activity was 12.63 FU/g. The optimal medium was soybeans soaked in 1% sucrose and soy protein isolated. The aglycones were about 20 time of soybeans, achieved 179.28 and 171.12 mg/100 g, respectively. The optimal condition for the steamed soybeans fermented by Bacillus subtilis BCRC 14718 at 45℃ for 32 hrs, the aglycones was achieved 182.87 mg/100 g, and the highest nattokinase activity was fermented for 16 hrs achieved 24.10 FU/g. To raise the nattokinase activity, the steamed soybeans were fermented by mix Bacillus subtilis BCRC 14718 and Bacillus spp. isolated from brand C at 45 ℃ for 48 hrs. The aglycones was achieved 156.95 mg/100 g after fermented 32 hrs, and the highest nattokinase activity was fermented for 16 hrs achieved 216.00 FU/g. According to this study, the nattokinase activity of steamed soybeans fermented by Bacillus subtilis BCRC 14718 were too low to contrast with commercial natto products, but the isoflavone aglycones were raised obviously. The steamed soybeans fermented by mix Bacillus subtilis BCRC 14718 and Bacillus spp. isolated from brand C can produce high contents of isoflavone and high activity of nattokinase.