摘要
针对作物类块根在发酵中存在的高粘度传质问题,研究了降粘酶在酿酒酵母发酵非粮能源作物新鲜木薯生产高浓度乙醇中的作用,为木薯原料更好地应用于规模化燃料乙醇生产提供理论依据.采用实验室优化后的降粘酶作用于液化后木薯发酵液,2 h后粘度由9×103mPa.s降到4×102mPa.s.在发酵过程中降粘酶的添加使发酵底物粘度在2-4 h内降低至200 mPa.s,由半固体变为流体,极大地增加了发酵底物的流动性,显著降低了搅拌需消耗的能量.结合降粘酶的前处理进一步开展了新鲜木薯高浓度乙醇发酵的研究.结果表明优化后的最佳条件为:新鲜木薯发酵初始糖浓度为24%,降粘酶用量为1 g/kg,最佳氮源为尿素,氮元素添加量为总发酵醪液的0.06%.发酵时间24 h,乙醇质量分数为115.57 g/kg,发酵效率达到91.92%,发酵强度为4.81 g kg-1h-1.在5 L发酵罐中,发酵效率达到90.16%,发酵强度4.78 g kg-1h-1.
This research studied the high viscosity in ethanol production from cassava with Saccharomyces cerevisiae and the use of viscosity reducing enzyme as annexing agent. It provided theoretical basis lbr ethanol fermentation with cassava on industry scale. Viscosity reducing enzymes optimized in our lab was used for pretreatment, which was followed by adding starch hydrolyzing enzymes in fermentation. Two hours later, the viscosity was reduced from 9x10^3 mPa.s to 4x10^2 mPa. s. In the fermentation process, the viscosity reducing enzymes decreased the viscosity to as low as 200 mPa.s in 2-4 hours, significantly increasing the liquidity of the cassava mash, which saved more energy in churning. The study of very high gravity （VHG） ethanol fermentation by S. eerevisiae found the following optimal conditions tbr VHG fermentation： the total sugar in the cassava root as 24%; viscosity reducing enzyme dosage as 1 g/kg; the best nitrogen source as carbamide when using the simultaneous saccharification and fermentation process; and the dosage of N as 0.06% of the total fermentation mash. Accordingly, the final ethanol concentration was up to t15.57 g/kg, with the ethanol efficiency 91.92% and ethanol productivity 4.81 g kg-1 h-t after 24 h. When the fermentation scale was expanded to 5 L, and the ethanol productivity was 4.78 g kg-1 h-1. Fig 4, Tab 5, Ref 10
出处
《应用与环境生物学报》
CAS
CSCD
北大核心
2013年第3期501-505,共5页
Chinese Journal of Applied and Environmental Biology
基金
国家科技支撑计划项目(2011BA D22B03)
中国科学院知识创新工程重要方向项目(KSCX2-EW-J-22
KSCX2-EW-G-1-1)
现代农业产业技术体系项目(CARS-11-A-04)资助~~
关键词
高浓度乙醇发酵
新鲜木薯
酿酒酵母
降粘酶
工艺优化
very high gravity ethanol fermentation
cassava
Saccharomyces cerevisiae
viscosity reducing enzyme
process optimization
