Nattokinase Activity Guided Natto Fermentation Process Optimization

Abstract

The natto kinase in natto has obvious thrombolytic effect, has the advantages of low cost, small side effects, long half-life and can be taken orally, so it has attracted much attention. At present, the research on natto kinase in our country mainly focuses on the selection of natto fermentation strains, the optimization of gene expression conditions and the exploration of thrombolytic mechanism. However, most natto products show that the number of viable bacteria is not high. Natto Kinase activity is low and no breakthrough has been made so far. For this reason, this topic has launched a study on how to improve the activity of natto kinase. This topic optimizes the traditional natto fermentation process and obtains the best fermentation parameters on the basis of enhancing the activity of natto kinase. The experiment first compared and selected two different fermentation strains and determined that Bacillus natto was the dominant fermentation strain. Considering that the water content of soybeans can indirectly affect the activity of natto kinase, the experiment explored the effects of soaking and steaming beans on the water content of soybeans and determined that soaking beans is an influencing factor for the fermentation process. During the fermentation process, soaking time, fermentation temperature, fermentation time and inoculation amount of superior species, were designed to explore the optimal fermentation process that make the highest nano kinase activity. The TAME method is used to accurately detect the activity of natto kinase in the samples after fermentation and the physical properties of the natto before and after fermentation are measured with a physical property test set. The data obtained can quantify the subjective sensory evaluation. Finally, the design-export 11.0 software was used to analyze and optimize the optimal fermentation process parameters with a soaking time of 15 h, a fermentation temperature of 37°C, a fermentation time of 30 h and an inoculum of 6 mL and the natto kinase activity under the combined conditions was measured to be 3 µ·mL^-1.