关键词: 豆乳, 液体发酵, 纳豆激酶, 工艺优化

Abstract: Nattokinase is an ideal natural drug for the prevention and treatment of thrombosis. Liquid fermentation can improve the yield of nattokinase. Taking Bacillus subtilis natto as the start culture, soybean milk as the fermentation medium, nattokinase activity as function evaluation index, the slag rate and finial pH as auxiliary indexes, the effects of fermentation time, liquid loading, bacteria loading and initial pH on nattokinase activity were studied by single factor and orthogonal analysis. The optimal fermentation conditions were determined as follows: The fermentation time was 30 h, the liquid volume in flask was 5%, the amount of bacteria was 1.75%, and the initial pH was 5.5. The nattokinase activity was 429 869.34 IU/mL under this condition, which was 5.41 times of that before optimization. It can be seen that the orthogonal test successfully optimized the liquid fermentation process of Bacillus subtilis natto and significantly increased the expression of nattokinase, which laied a theoretical foundation for the development of functional food.

Key words: soybean milk, liquid fermentation, nattokinase, optimization