The Study On Optimization Of Fermentation Conditions And Physicochemical Characteristics Of Kidney Beans Phaseolus Vulgaris Inoclulated With Bacillus Natto

As a traditional fermented soy food, Natto nutrition is rich, so this paper preliminary studied using different raw materials made from fermented natto products, and ultimately found that soybean and kidney beans Phaseolus vulgaris as the material of natto products on the sensory index is superior to other legumes. On this basis, we studied the fermentation process using the response surface method to optimize the fermentation conditions optimized by using kidney beans Phaseolus vulgaris as materials inoculated with Bacillus Natto. At the same time we compared the changes of the characteristics, texture and volatile flavor substances in soybean natto and kidney bean natto under different fermentation time.Experiments and results can be divided into the following several aspects:1. In the optimization process of kidney bean natto, The single factor experiments were conducted by setting different fermentation conditions including inoculation amount,fermentation time and fermentation temperature. A series of experimental programs were designed by Central Composite Design in the response surface software. The optimal fermentation conductions were obtained.The results showed that the optimal fermentation conditions for kidney bean natto were determined as followed : the steamed kidney bean was inoculated with 5.56% Bacillus natto, fermented for 22.30 h at 34.11℃ when amino nitrogen content(AAN) as a response value. At this condition, AAN content reached the maximum0.474%. When reducing sugar content(RS) as a response value, the steamed kidney bean was inoculated with 5.33% Bacillus natto, fermented for 14.35 h at 33.96℃, the RS content reached the maximum4.993%.2. soybean and kidney bean natto inoculated Bacillus natto and fermentation 48 h, with the increase of fermentation time, the changes of characteristics and antioxidant activity were found that:(1) The moisture content of soybean increased significantly;(2) The RS content reached the maximum at 12 h, then gradually decreased followed by the increases of fermentation time, but still higher than the content of unfermented product;(3) The total nitrogen content showing a trend of a prior rise in the lower;(4)The AAN content and trichloroacetic acid nitrogen(TCA-N) content in soybean were gradually increased with the increase of fermentation time and reached the highest at 48 h. But on the contrary, the variation of AAN in kidney bean at 48 h reached a minimum value;(5)In the fermentation process of kidney bean, the DPPH radical scavenging efficiency decreased as fermentation time increased. In soybean, the DPPH scavenging effect was increased at first and wherein the clearance rate reached the highest value in 24 h.3. The changes sensory quality such as texture and volatile flavor substances in soybean and kidney bean in the fermentation process were investigated and found that:(1)The viscosity of two types of natto raised with increasing of fermentation time, reached a maximum at 36 h,and the viscosity of kidney bean was higher than soybeans;(2) Three indicators including hardness, chewiness, adhesiveness in two kinds of natto showed a regular change with increasing fermentation time;(3) The main characteristic flavor in natto was nitrogen oxides,sulfides,and aromatic compounds after the determination of electronic nose.