Ethanol Production From Jerusalem Artichoke Tubers

Jerusalem artichoke has been considered as an alternative source of carbohydrates for fuel ethanol production.In this study,batch and continuous cultures were firstly conducted to establish the optimum operating conditions to ferment Jerusalem artichoke juice to ethanol using self-flocculating yeast Saccharomyces cerevisiae flo.Then,the simultaneous saccharification and fermentation was developed using the unsterilized Jerusalem artichoke meal with the inulinase-producing strain Kluyveromyces.In the process of fermentation with Jerusalem artichoke juice,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 and 82 g/L were achieved within 18 h and 24 h when Jerusalem artichoke juice was supplied at 103 g/L and 179 g/L 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 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/ hand 0.53 g dry g/L/h, respectively.The production of ethanol by simultaneous saccharification and fermentation,using Jerusalem artichoke flour which was screened with sieve number 60 as raw material is presented.The simultaneous saccharification and fermentation method was used to optimize the uncooked Jerusalum artichoke flour for the production of ethanol with the inulinase strain Kluyveromyces cicerisporus Y 179.Optimization of four parameters,including culture time in stage of breeding,feeding time of Jerusalum artichoke flour,pectinase concentration and dissolved oxygen,was attempted for the optimal production of ethanol in 2.5 L bioreactor. The optimum conditions were found to be that Kluyveromyces cicerisporus Y179 was cultured 24h under aerobic conditions and Jerusalum Artichoke flour was feeding at 24th h during fermentation.Additionaly,the experimental of dissolved oxygen in bioreactor indicated that the average ethanol fermentation time was decreased to 48h from 72h at the aeration condition and get less residual total sugar,but higher ethanol yield was obtained under non-aeration conditions with more substrate directed to ethanol production.The viscosity of fermentation substrate was diminished to half as the pectinase concentration was 10 U/g.At the optimum conditions,the maximum predicted ethanol yield of 90.51%was obtained with the substrate containing 280 g/L dry Jerusalem artichoke flour.The experiments of nutrition addition suggested that(NH₄)₂SO₄ and urea had no effect on the ethanol fermentation.KH₂PO₄ supplement was found to improve ethanol productivity and the optimal addition of KH₂PO₄ was 0.15 g/L which was required.Taking into account above two fermentation processes,we states the engineering route for commercial ethano production from Jerusalum artichoke.A distributed eco-industrial system of fuel ethanol from Jerusalem artichoke was constructed,which contained following processes:Jerusalem artichoke planting,crude ethanol production,refined ethanol production and byproduct utilization.