Study On The Key Factors Influencing The Quality Of Natto Powder

Natto originates from traditional Chinese fermented food cardamom with high nutritional value and multiple physiological functions.However,due to the special ammonia smell produced during the fermentation of natto,it is not easily accepted by partial Chinese.If the natto is dried and made into natto powder,it will reduce the ammonia smell to a certain extent,but it will have a certain influence on the quality of natto powder.In order to produce natto powder suitable for Chinese taste and to ensure the high quality of natto powder,this subject explored the effects of different drying methods,different Bacillus natto strain and different bean raw materials on the quality of natto powder,the optimal fermentation natto condition and the optimal dry natto process were selected to produce high quality natto powder,and the storage stability of natto powder was studied.The main research contents and conclusions include three aspects.(1)Study on the effect of different drying methods on the quality of natto powder.The effects of vacuum freeze-drying and hot air drying on natto viable count and nattokinase activity in natto powder were compared,and the sensory evaluation of natto powder prepared by different drying methods was carried out.The experimental results show that when the moisture content of natto powder is kept within 3%,the dry natto viable count in natto decreased from 2.56×10~9CFU/g to 8.97×10~8 CFU/g after vacuum freeze-drying of fresh natto for 12 h,the loss rate of Bacillus natto was 64.9%,and the dry nattokinase activity in natto decreased from 6532 IU/g to 5246 IU/g,the loss rate of nattokinase activity was19.6%.When they were dried by hot air at a drying temperature of 60-65?for24 hours,although the loss rate of nattokinase activity was as high as 36.8%,but the loss rate of Bacillus natto was as low as 2.3%,and the sensory evaluation of natto baking powder was better than that of natto freeze-dried powder.Therefore,the application of hot air drying technology on the industrial production of natto powder can not only guarantee the quality of natto powder to a certain extent,but also improve production efficiency as well as reduce production cost.(2)The preference of the Bacillus natto strain and its effect on the quality of natto powder.Comparing the sporulation rate and heat tolerance of different Bacillus natto strains,the Bacillus natto strain was used to ferment natto,and the Box-Behnken response surface experiment was used to optimize the fermented natto condition of Bacillus natto strain.The natto was dried by the optimal drying method to make the natto powder,and the effect of the preferred Bacillus natto strain on the quality of the natto powder was investigated.The results showed that the Bacillus natto strain S3 had higher spore production rate and better spore heat resistance.Therefore,Bacillus natto strain S3 was selected for fermenting natto,Under the condition of the inoculation amount was 7%,and the fermentation temperature was 37?,the fermentation time of 30 h,the highest value of dry nattokinase activity of fermented natto was 7889 IU/g,and the highest dry natto viable count was 2.99×10~9 CFU/g.Compared with Yanjing natto powder,the nattokinase activity value was 6181 IU/g,the nattokinase activity loss rate was 21.6%,and natto viable count was relatively high at2.94×10~9 CFU/g after Bacillus natto strain S3 fermented natto dried,and the sensory quality score of natto baking powder was slightly higher.(3)Study on the effect of different beans on the quality of natto powder.The effects of different types of beans and different origins of soybeans on the quality of fermented natto were compared.The best fermented natto raw materials,the optimal fermented natto condition,and the best dried natto method were used to make high quality natto powder.Explore the main components and storage stability of high quality natto powder.The experimental results showed that if the northeast small soybeans are selected as raw materials,the natto viable count and nattokinase activity in the fermented natto was higher under the conditions of inoculating 7%,fermentation temperature of 37?and fermentation time of 30 h.It was 3.41×10~9 CFU/g,8767 IU/g,and the sensory evaluation of natto was the best.The natto viable count and nattokinase activity of dried natto powder were also higher,and the sensory evaluation was better.Compared with the raw soybean powder,the nutritional value of the high quality natto baking powder was also good,and the high quality natto baking powder was stable under normal temperature conditions of 25?and had a long storage period.This subject takes advantages of hot air drying technology to produce natto baking powder with more natto viable count and good sensory quality by giving preference to the raw materials and strains of natto fermentation and optimizing the fermentation process of natto,which improves production efficiency,reduces production cost and provides technical support for the industrial production of natto powder.