| Scope and method of study. Specific objective of the study was to determine if it was really possible to carry out in-field fermentation of sweet sorghum juice to ethanol with little or no process control. The main objectives of present research are to determine the effect of numerous process variables (yeast type, pH, nutrient and agitation) on in-field ethanol production from sweet sorghum and to determine the nutrient stability of sorghum juice. Testing of parameters enabled us to understand the impact of each variable on the fermentation performance and the sugar to ethanol conversion efficiency. Initial laboratory experiments were conducted to screen different types of fermenting microorganism (Zymomonas mobilis, Kluyveromyces marxianus and industrial dry distillers yeast, Saccharomyces cerevisiae ), optimum temperature conditions (7, 37, and 7 and 41°C), optimum pH conditions (pH 4.3, 4.3 and 5.4) and the agitation effect. Two in-field factorial design experiments were conducted using various vessel sizes: 3.8 L, 19 L and 209 L with variables being yeast from two different suppliers (Fermax and Superstart Distillers S.cerevisiae), nutrients (with and without urea) and pH (5.4 and 4.3). (Abstract shortened by UMI.)... |
