| Summary: | 碩士 === 中國文化大學 === 生活應用科學研究所 === 93 === Natto is a traditional fermented soybean food in Japan, which is made by fermenting steamed soybean with Bacillus natto. It is characterized by unique viscous material and flavor, and has various physiological functions. In this study, we used green-cotylendon black soybean (Tainan No. 3) as raw material which is better than normal soybean for biological activities, and using response surface methodology (RSM) to determine the physical properties (hardness, viscosity and color), enzymatic activities (nattokinase activity and protease activity), chemical properties (DPPH free radical scavenging ability, γ-polyglutamic acid and ammonia) and nitrogen compounds (TCA-soluble nitrogen and solubilization ratio of protein) of the natto products at different roasting times (black soybean:0~8 min), inoculated bacteria populations (black soybean:101~105 cells/100g) and fermentation times black soybean:6~30 hr) to obtain the optimum process of black soybean natto. Furthermore, manufacturing black soybean natto with the optimizing process to compare with commercial nattos to understand the differences between these two products. These results were as follows:
1. The optimized process for black soybean natto is: roasting time of 3 minutes, inoculated bacteria populations at 103 cells/100g, fermentation time of 24 hours.
2. The physical properties of natto－hardness, viscosity and color were all affected simultaneously by roasting time, inoculated bacteria population and fermentation time. The hardness decreased with prolonged cooking time, but increased at inadequate or excessive degree of fermentation. It is thought that the variation was influenced by the fermentation stage it had reached. The maximum viscosity was achieved at the shorter roasting time and longer fermentation time. The roasting time is the primary influence factor for color changes.
3. The nattokinase activity and protease activity of black soybean natto is at its maximum at the higher inoculated bacteria populations and longer fermentation time.
4. TCA-soluble nitrogen and γ-PGA is at its maximum at the longer inoculated bacteria populations and fermentation time. Ammonia was simultaneously affected by roasting time, inoculated bacteria population and fermentation time.
5. The TCA-soluble nitrogen of black soybean natto is also at its maximum at the longer roasting and fermentation times. The solubilization ratio of protein was simultaneously affected by inoculated bacteria population and fermentation time.
6. The hardness and ammonia content of roast broken black soybean natto made through optimizing process were lower than commercial nattos. The nattokinase activity of black soybean natto made through optimizing process and from commercial nattos was equal. These results can be used for making commercial natto product from black soybean.
7. For the sensory evaluation test the roast broken black soybean natto rated higher on the hedonic scale than the commercial nattos.
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