Research On Natto Processing Technology And Product Development

With the high nutritional value and physiological function, natto has been a kind oftraditional fermented food in Japan. Being the most important functional component,nattokinase has caused hot attention based on its strong thrombolytic function.Considering the rapid step of our aging society, it becomes more important to improvethe function and the practicality of natto in China.In this thesis, based on the strain preserved in our laboratory, after ultravioletmutagenesis, the casein plates and the fibrin plates were successively selected to screenstrains and a strain with a greater capacity of nattokinase-production than the originalstrain was obtained, temporarily named SG-1, which also had a strong genetic stability.Getting the high-yield strain, the effect of the fermentation conditions onnattokinase activity was researched. Through the analysis of the single factorexperiments and orthogonal experiment, ultimately the optimum fermentationconditions was obtained as follows: the water content was70%, soybean thickness was2.5cm, sterilization time was30min, inoculation amount was6%, seed age was15h, thefermentation temperature was38℃, fermentation time was22h. Results of the threeadditional tests with the optimum fermentation conditions demonstrated that nattokinaseactivity was the maximum1455.6U/g. Compared with the four types of natto as follows,the two kind of natto in market, natto based on original strains and bacteria powder, thenattokinase activity was determined32.6%,38.1%,32.0%and47.0%higherrespectively. Therefore the validity of the experiments was proved to achieve thepurpose.Natto fermentation conditions were adjusted, adding1%sodium glutamate,6%teaand2%sucrose, and after-ripening for1d. After fermentation, the season wrap has beendeveloped, making the taste of natto more suitable for Chinese people. The experimentwas performed to explore the preservation way of the natto, adding3%trehalose toprotect the nattokinase, which significantly prolong the retention time of natto at4℃and﹣20℃.