Monday, August 11, 2008
P22

Ethanol production from Jerusalem artichoke juice using self-flocculating yeast

Baolei Chang, Wenjie Yuan, Xinqing Zhao, and Fengwu Bai. Department of Bioscience and Bioengineering, Dalian University of Technology, Linggong Road 2, Dalian, 116024, China

Jerusalem artichoke has been considered as an alternative source of carbohydrates for fuel ethanol production. In this study, batch and continuous cultures were conducted to establish the optimum operating conditions to ferment Jerusalem artichoke juice to ethanol using self-flocculating yeast Saccharomyces cerevisiae flo. Ethanol production were studied using two techniques: one is the separate hydrolysis fermentation (SHF) which hydrolyzed Jerusalem artichoke juice by inulinase following by fermenting the sugar released with the self-flocculating yeast; the other is the simultaneous saccharification and fermentation (SSF) of Jerusalem artichoke juice using self-flocculating yeast. At the same time, unsterilized Jerusalem artichoke juice was investigated in the two different operations comparing with the sterilized juice. The results showed that SSF produced more ethanol and the fermentation time was much shorter comparing with the SHF technique. What’s more, no difference in ethanol production was found when unsterilized Jerusalem artichoke juice was used as substrate. The highest ethanol concentration of 50 g l-1 and 82 g l-1 were achieved within 18 h and 24 h when Jerusalem artichoke juice was supplied at 103 g l-1 and 179 g l-1 in the batch culture using SSF, 15% and 8% higher than the SHF method. Steady states were observed when the dilution rate of 0.02 h-1 in continuous stirred-tank bioreactor using SSF, and 90 g l-1 ethanol was produced, equivalent to 90% of the theoretical value of 0.511, and the ethanol productivity and the biomass productivity were 2.82 g l-1 h-1 and 0.53 g dry wt l-1 h-1, respectively.

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