United States Department of Agriculture, Agricultural Research Service (ARS), Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
United States Department of Agriculture, Agricultural Research Service (ARS), Eastern Regional Research Center, 600 East Mermaid Lane, Wyndmoor, PA 19038, USA.
Bioresour Technol. 2014 Feb;154:18-25. doi: 10.1016/j.biortech.2013.11.043. Epub 2013 Nov 27.
The effects of acid protease and urea addition during the fermentation step were evaluated. The fermentations were also tested with and without the addition of urea to determine if protease altered the nitrogen requirements of the yeast. Results show that the addition of the protease had a statistically significant effect on the fermentation rate and yield. Fermentation rates and yields were improved with the addition of the protease over the corresponding controls without protease. Protease addition either with or with added urea resulted in a higher final ethanol yield than without the protease addition. Urea addition levels >1200 ppm of supplemental nitrogen inhibited ethanol production. The economic effects of the protease addition were evaluated by using process engineering and economic models developed at the Eastern Regional Research Center. The decrease in overall processing costs from protease addition was as high as $0.01/L (4 ¢/gal) of denatured ethanol produced.
评估了在发酵步骤中添加酸蛋白酶和尿素的效果。还测试了添加和不添加尿素的发酵，以确定蛋白酶是否改变了酵母的氮需求。结果表明，添加蛋白酶对发酵速度和产率有统计学上的显著影响。与不添加蛋白酶的相应对照相比，添加蛋白酶可提高发酵速度和产率。添加蛋白酶（无论是否添加尿素）的最终乙醇产率均高于不添加蛋白酶的情况。添加的尿素量超过 1200ppm 的补充氮会抑制乙醇的生产。通过在东方区域研究中心开发的过程工程和经济模型，评估了添加蛋白酶的经济效果。添加蛋白酶可使总成本降低高达每升变性乙醇 0.01 美元（每加仑 4 美分）。
