Viscosity Reduction During Fuel Ethanol Production by Fresh Sweet PotatoFermentation

Abstract

Fresh sweet potato is one of the major feedstocks for fuel ethanol production in China.However,high-viscosity syrup is the key factor affecting high gravity fermentation of fresh sweet potato.It easily leads to pipe block,which seriously reduces the ethanol fermentation efficiency,influences the industrial production of ethanol with fresh sweet potato and increases the energy consumption.In this paper,the experiments on the viscosity-reducing enzyme and its optimized conditions were carried out,and the results showed that:(1) The cellulase from Sichuan Habio Bioengineering Co.,Ltd was the best enzyme,reducing the viscosity from 1.7×104 mPa.s to 8.8×102 mPa.s,and greatly reduced the cost of ethanol production.(2) The optimal pretreated condition was 110 ℃ for 20 min.(3) The viscosity-reducing enzyme could be applied to different varieties of fresh sweet potatoes,and the viscosity all reduced to less than 1.0×103mPa.s,with the lowest value of 2.7×102mPa.s.The viscosity reduction rates were all more than 95%.(4) Under optimal conditions,the viscosity of fermented sweet potatoes decreased from 1.9×105mPa.s to 2.7×103mPa.s after treated for 2 h by enzyme,and reduced to 790 mPa.s after fermentation of 23 h.The ethanol concentration reached 10.56%(V/V).The results were validated further that the viscosity-reducing enzyme had potential in industrial scale ethanol fermentation with fresh sweet potato.Tab 8,Ref 19