Optimization of pre-saccharification time during dSSF process in oat-hull bioethanol technology.

Abstract

This study suggests a mathematical description and the optimization of the pre-saccharification time during simultaneous saccharification and fermentation with delayed yeast inoculation (dSSF) to ensure the fastest and fullest possible conversion of a substrate into the target product-bioethanol. A pulp derived by alkaline delignification of oat hulls was used as a substrate. The pre-saccharification step of oat-hull pulp was performed at a solid loading of 60g/L, at 46 ± 2°C, using mixed enzymes CelloLux-A and BrewZyme BGX, the pre-saccharification time was 8, 15, 24, 39, 48 and 72h. Afterwards, the reaction mixture was cooled to 28°C, a 10% inoculum of Saccharomyces cerevisiae Y-1693 was seeded, and fermentation combined with saccharification. The optimum pre-saccharification time (inoculation time) under these conditions was found to be 24h, thus providing the maximum hydrolysis of cellulose and hemicelluloses and the highest yield of bioethanol. The procedure suggested herein for determining the optimum pre-saccharification time can be used for other model substrates from lignocellulosic feedstocks.