Fermentation Process Of Natto-pigeonpea Bean With Immobilized Bacillus Natto And Its Preliminary Assessment Of Quality

Natto,a traditional fermented legumes product,has a strong fibrinolytic activity.In recent years,the prevalence of cardiovascular disease continued to increase in our country.In order to prevent and cure these diseases,it is particularly important to promote the natto products.Traditional natto based mainly on soybean,however,it was not very suitable for Bacillus natto to grow on soybean because of its high fat reversely.Moreover,solid-state fermentation was not only costly and time-consuming,but also inefficiency.Based on the above issues,pigeonpea bean,the only woody economic crops,was chosen as raw materials for fermentation,and immobilization technology was applied.In this study,the immobilized conditions of Bacillus natto and fermentation process with immobilized microorganisms were optimized.In addition,a preliminary assessment of quality was studied and a new type of fermentation equipment was applied in preparation of natto-pigeonpea bean with immobilized Bacillus natto.1.The immobilized conditions of Bacillus natto were optimized.The sodium alginate embedding method of immobilized microorganisms was applied in preparation of natto-pigeonpea bean.The optimal immobilization conditions for Bacillus natto with the index of fribrinolytic activity of natto-pigeonpea bean were as follows:alginate concentration 7.0%,CaCl2 concentration 2.5%,concentration of bacterium 7.4 log cfu/mL and alginate bead diameter 5.0 mm.The fribrinolytic activity of natto-pigeonpea bean with immobilized Bacillus natto and free microbe were 1376±3.09 IU/g and 1389±2.14 IU/g,respectively.There was no great difference between them,which meant the method of immobilized microorganisms had a little influence on the activity of Bacillus natto.In the stability experiment,it was shown that the immobilized Bacillus natto can be used for 15 times in the fermentation process.The preparation technics of immobilized Bacillus natto is reasonable,which can be adaptive to the requirement of industry.2.The fermentation conditions of natto-pigeonpea bean were optimized.In order to evaluate the effect of fermentation conditions on the fribrinolytic activity of natto-pigeonpea bean,the fermentation process was investigated compared to natto-soybean.After that,the response surface analysis was applied to obtain the optimum fermentation conditions.The fribrinolytic activity of product reached 1917.05 ± 1.34 IU/g under the optimal conditions:pH 6.5,temperature 38℃,time 48 h,wet weight of microorganism beads 0.8 g/g material and ratio of liquid to solid 15:1 mL/g.3.The preliminary assessment of quality on natto-pigeonpea bean were investigated.In this study,the antioxidant capacity of natto-pigeonpea bean was detected by DPPH radical scavenging test and and β-Carotene-linoleic acid bleaching test.The results showed that the antioxidant capacity of natto-pigeonpea bean was a little superior to that of natto-soybean.The IC50 value concentration and the clearance of super oxygen free radical of natto-pigeonpea bean were 0.3373±0.0611 mg/mL,0.0839±0.0092 mg/mL,while that of natto-soybean were 0.3588±0.0902 mg/mL,0.0943±0.0037 mg/mL,respectively.In the experiment of sensory evaluation,there was no significant difference between natto-pigeonpea bean and natto-soybean on physical appearance.However,natto-pigeonpea bean had better aroma,colour,taste and solubility than natto-soybean.5.The fermentation process of natto-pigeonpea bean was verified by pilot experiment.A self-developed fermentation equipment was applied in preparation of natto-pigeonpea bean.It was showed that fribrinolytic activity of natto-pigeonpea bean was 1898.11±2.01 IU/g,which was a little lower than that of previous experiments,but there was no visible difference between them.The IC50 value concentration of DPPH radical scavenging test and and-βCarotene-linoleic acid bleaching test were 0.3413±0.0231 mg/mL、0.0857±0.0051 mg/mL,also similar to the results of previous experiments.In conclution,the fermentation equipment was appropriate for preparation of natto-pigeonpea bean efficiently and continuously.