运用分离自云南传统发酵豆豉的Bacillus subtilis SP-8-5与Lactobacillus plantarum YM-5-2菌株对大豆进行两步固态混合发酵。首先,将菌株B.subtilis SP-8-5接种至经室温浸泡10 h(20℃,质量比为1∶3),110℃(20min)蒸煮处理并冷却至30℃的大豆中,于26℃进行初步发酵42 h;随后再接种L.plantarum YM-5-2,并于30℃发酵2 d,最后置于4℃进行后发酵。经两步固态混合发酵处理后,得到一种纤溶活性较强,生产周期短,保质期相对较长,风味独特且易于被大众接受的新型功能性发酵豆豉。当后发酵时间为21 d时,样品豆豉中B.subtilisSP-8-5活菌数为(5.88±0.53)×108 CFU/g,而L.plantarum YM-5-2活菌数则高达(3.50±0.35)×1011 CFU/g,此时检测豆豉纤溶酶的纤溶圈直径高达(2.99±0.06)cm(37℃,静置培养48 h)。

A functional Douchi was fermented by two-step solid fermentation using Bacillus subtilis SP-8-5 and Lactobacillus plantarum YM-5-2 isolated which were isolated from Yunnan traditional fermented Douchi.At first,soybean seeds were soaked by water in ratio of 1∶ 3(w/w) at room temperature(20 ℃) for 10 h,then the soaked seeds were sterilized for 20 min at 110 ℃ and cooled to 30 ℃.B.subtilis SP-8-5 was inoculated into the sterilized seeds for first solid fermentation step at 26 ℃ for 42 h.After 42 h cultivation,L.plantarum YM-5-2 was added and fermented for second step at 30 ℃ for 2 days.Through this procedure,a functional Douchi possessing special flavor with strong fibrinolytic activity,short fermented period,high nutrition value and long shelf life was successfully obtained.After 21 days post-fermentation,the living bacteria amount of B.subtilis SP-8-5 and L.plantarum YM-5-2 could reached as high as(5.88±0.53)×108 CFU/g and(3.50±0.35)×1011 CFU/g respectively.Meanwhile the fibrinolytic activity was the highest through measuring the diameter of clear zone on fibrin plate.