Scientia Agricultura Sinica ›› 2016, Vol. 49 ›› Issue (9): 1757-1766.doi: 10.3864/j.issn.0578-1752.2016.09.012


• STORAGE·FRESH-KEEPING·PROCESSING • Previous Articles     Next Articles

Establishment of a Viscosity Reduction Process by Enzymatic Pretreatment and Its Application in Ethanol Fermentation from Fresh Sweet Potato Without Adding Water

YUE Rui-xue, NIU Fu-xiang, SUN Jian, XU Fei, WANG Hong-yun, ZHU Hong, ZHANG Yi   

  1. Xuzhou Institute of Agricultural Sciences in Xuhuai District/ Sweet Potato Research Institute, Chinese Academy of Agricultural Sciences, Xuzhou 221131, Jiangsu
  • Received:2015-11-02 Online:2016-05-01 Published:2016-05-01

Abstract: 【Objective】 The objective of this research was to establish a viscosity reduction process for fresh sweet potato (FSP) mash by enzymatic pretreatment before liquification and use it for direct ethanol fermentation from FSP without adding additional water. 【Method】 A total of 12 kinds of starch-type sweet potatoes (SP), widely cultured in China, were selected for this research. The main components of SP, such as dry matter, starch, protein, soluble sugars, pectin, hemicellulose, cellulose, and lignin, were detected and the correlation between these components and viscosity of FSP were analyzed. Based on the results, proper enzymes, cellulase and pectinase, were selected for viscosity reduction. Effects of some key factors of enzymatic pretreatment on viscosity reduction were investigated, including the ratio of substrate to water (1:0, 2:1, 3:2, 5:4, and 1:1), enzymatic pretreatment time (1, 2, 3, 4, and 5 h), enzymes doses (cellulase: 1.0, 1.5, 2.0, 2.5, and 3.0 GCU·g-1 and pectinase: 1.0, 1.5, 2.0, 2.5, and 3.0 U·g-1), and enzymatic pretreatment temperatures (30, 40, 50, 60, and 70). The optimum enzymatic pretreatment conditions were determined by orthogonal experiment design and the effects of enzymatic pretreatment on the following ethanol fermentation performance from FSP were also investigated. 【Result】 For 12 kinds of tested starch-type sweet potato varieties, except for hemicellulose (r=-0.239) and lignin (r=-0.069), all the components were positively correlated to the viscosity (dry matter content, r=0.356; starch, r=0.211, soluble sugar, r=0.307; protein, r=0.266; pectin, r=0.526; cellulose, r=0.600). Wherein the pectin (P<0.01) and cellulose (P<0.05) were significantly positively correlated to the viscosity. According to the range analysis, the factors affecting enzymatic treatment effects from high to low were enzyme dosage, the ratio of substrate to water, enzymatic treatment time, and temperature. Based on the experiment results and the consideration on the industrial application, the optimum enzymatic pretreatment conditions were determined as: the ratio of substrate to water 1﹕0, cellulase 1.5 GCU·g-1, pectinase 1.5 U·g-1, and 50 for 3 h. Besides Wansu 178, mash viscosity from other varieties after enzyme treatment was lower than 3 000 cp, and the viscosity reduction rate was 95.07%-99.31%. At the end of fermentation, the ethanol concentration from 11 kinds of SP varieties was higher than 12% (v/v), and the fermentation efficiency of 9 varieties reached more than 90%. 【Conclusion】 Pectin and cellulose are the main factors affecting the viscosity of SP mash. Fresh SP mash can be directly used for ethanol fermentation after enzymatic pretreatment without adding water.

Key words: fresh sweet potato, viscosity, enzyme treatment, ethanol fermentation, cellulase, pectinase

[1]    Baeyens J, Kang Q, Appels L, Dewil R, Lv Y, Tan T. Challenges and opportunities in improving the production of bio-ethanol. Progress in Energy and Combustion Science, 2015, 47: 60-88.
[2]    Bhutto A W, Harijan K, Qureshi K, Bazmi A A, Bahadori A. Perspectives for the production of ethanol from lignocellulosic feedstock-A case study. Journal of Cleaner Production, 2015, 95: 184-193.
[3]    EI Sheikha A F, Ray R C. Potential impacts of bio-processing of sweet potato: review. Critical reviews in food science and nutrition, 2015. doi: 10.1080/10408398.2014.9609.09.
[4]    Deesuth O, Laopaiboon P, Klanrit P, Laopaiboon L. Improvement of ethanol production from sweet sorghum juice under high gravity and very high gravity conditions: Effects of nutrient supplementation and aeration. Industrial Crops and Products, 2015, 74: 95-102.
[5]    Liu H H, Ren L T, Spiertz H, Zhu Y B, Xie G H. An economic analysis of sweet sorghum cultivation for ethanol production in North China. Global Change Biology Bioenergy, 2015, 7(5): 1176-1184.
[6]    Chu C Y, Sen B, Lay C H, Lin Y C, Lin C Y. Direct fermentation of sweet potato to produce maximal hydrogen and ethanol. Applied Energy, 2012, 100: 10-18.
[7]    Jin Y L, Fang Y, Zhang G H, Zhou L L, Zhao H. Comparison of ethanol production performance in 10 varieties of sweet potato at different growth stages. Acta oecologica-International Journal of Ecology, 2012, 44: 33-37.
[8]    Shen Y, Guo J S, Chen Y P, Zhang H D, Zheng X X, Zhang X M, Bai F W. Application of low-cost algal nitrogen source feeding in fuel ethanol production using high gravity sweet potato medium. Journal of Biotechnology, 2012, 160(3/4): 229-235.
[9]    Lay C H, Lin H C, Sen B, Chu C Y, Lin C Y. Simultaneous hydrogen and ethanol production from sweet potato via dark fermentation. Journal of Cleaner Production, 2012, 27: 155-164.
[10]   甘明哲, 靳艳玲, 周玲玲, 戚天胜, 赵海. 适合鲜甘薯原料乙醇发酵的低黏度快速糖化预处理. 应用与环境生物学报, 2009, 15(2): 262-266.
Gan M Z, Jin Y L, Zhou L L, Qi T S, Zhao H. Low viscosity and rapid saccharification pretreatment of fresh sweet potato for ethanol production. Chinese Journal of Applied and Environmental Biology, 2009, 15(2): 262-266. (in Chinese)
[11]   HUAng H Y, Jin Y L, SHEN W L, Fang Y, ZHaNG G H, ZHAO H. The use of plant cell wall-degrading enzymes from newly isolated Penicillium ochrochloron Biourge for viscosity reduction in ethanol production with fresh sweet potato tubers as feedstock. Biotechnology and Applied Biochemistry, 2014, 61(4): 480-491.
[12]   Zhang L, Chen Q, Jin Y L, Xue H L, Guan J F, Wang Z Y, Zhao H. Energy-saving direct ethanol production from viscosity reduction mash of sweet potato at very high gravity (VHG). Fuel Processing Technology, 2010, 91(12): 1845-1850.
[13]   Hang P, Chen C F, Shen Y H, Ding T L, Ma D F, Hua Z C, Sun D X. Starch saccharification and fermentation of uncooked sweet potato roots for fuel ethanol production. Bioresource Technology, 2013, 128: 835-838.
[14]   Shen Y, Zhang H D, Zheng X X, Zhang X M, Guo J S, Chen Y P. Very high gravity fermentation using sweet potato for fuel ethanol production. Application of Chemical Engineering, 2011, 236-238: 59-62.
[15]   黄玉红, 靳艳玲, 赵云, 李宇浩, 方扬, 张国华, 赵海. 鲜甘薯发酵生产燃料乙醇中的降黏工艺. 应用与环境生物学报, 2012, 18(4): 661-666.
Huang Y H, Jin Y L, Zhao Y, Li Y H, Fang Y, Zhang G H, Zhao H. Viscosity reduction during fuel ethanol production by fresh sweet potato fermentation. Chinese Journal of Applied and Environmental Biology. (in Chinese), 2012, 18(4): 661-666
[16]   Huang Y H, Jin Y L, Fang Y, Li Y H, Zhao H. Simultaneous utilization of non-starch polysaccharides and starch and viscosity reduction for bioethanol fermentation from fresh Canna edulis Ker. tubers. Bioresource Technology, 2013, 128: 560-564.
[17]   Huang Y H, Jin Y L, Fang Y, Li Y H, Zhang G H, Xiao Y, Chen Q, Zhao H. Simultaneous saccharification and fermentation (SSF) of non-starch polysaccharides and starch from fresh tuber of Canna edulis ker at a high solid content for ethanol production. Biomass & Bioenergy, 2013, 52: 8-14.
[18]   岳瑞雪, 孙健, 钮福祥, 徐飞, 张爱君. 长期定位施肥对甘薯品质、RVA特性和乙醇发酵特性的影响及其相互关系. 江苏农业学报, 2013, 29(1): 87-92.
Yue R X, Sun J, Niu F X, Xu F, Zhang A J. Effect of long-term located fertilization on quality, starch RVA profile characteristics, ethanol fermentation of sweetpotato and their relationships. Jiangsu Journal of Agricultural Sciences, 2013, 29(1): 87-92. (in Chinese)
[19]   孙健, 钮福祥, 岳瑞雪, 徐飞, 朱红. 甘薯膳食纤维构成及对乙醇发酵的影响. 中国粮油学报, 2014, 29(5): 18-22.
Sun J, Niu F X, Yue R X, Xu F, Zhu H. Analysis of dietary fiber from sweetpotato and its effect on ethanol fermentation. Journal of the

Chinese Cereals and Oils Association, 2014, 29(5): 18-22. (in Chinese)
[20]   岳瑞雪, 孙健, 钮福祥, 徐飞, 朱红. 响应面分析法优化甘薯乙醇发酵条件. 核农学报, 2014, 28(8): 1400-1406.
Yue R X, Sun J, Niu F X, Xu F, Zhu H. Optimization of ethanol fermentation from sweet potato by response surface methodology. Journal of Nuclear Agricultural Sciences, 2014, 28(8): 1400-1406. (in Chinese)
[21]   Kim Y H, Park S C, Ji C Y, Lee J J, Jeong J C, Lee H S, Kwak S S. Diverse antioxidant enzyme levels in different sweetpotato root types during storage root formation. Plant Growth Regulation, 2015, 75(1): 155-164.
[22]   Chen H J, Liang S H, Huang G J, Lin Y H. Sweet potato cysteine proteases SPAE and SPCP2 participate in sporamin degradation during storage root sprouting. Journal of Plant Physiology, 2015, 186: 39-49.
[23]   张有林, 张润光, 王鑫腾. 甘薯采后生理、主要病害及贮藏技术研究. 中国农业科学, 2014, 47(3): 553-563.
Zhang Y L, Zhang R G, Wang X T. Study on postharvest physiology, main diseases and storage technology of sweet potato. Scientia Acricultura Sinica, 2014, 47(3): 553-563. (in Chinese)
[24]   王炜, 李鹏霞, 胡花丽, 王毓宁. 甘薯在贮藏期间细胞壁降解酶活性的变化. 食品与发酵工业, 2012, 38(7): 186-189.
Wang W, Li P X, Hu H L, Wang Y N. Study on the activity of cell wall degradation enzyme of sweet potato in its storage. Food and Fermentation Industries, 2012, 38(7): 186-189. (in Chinese)
[25] Huang Y H, Busk P K, Lange L. Cellulose and hemicellulose- degrading enzymes in Fusarium commune transcriptome and functional characterization of three identified xylanases. Enzyme and Microbial Technology, 2015, 73: 9-19.
[26]   Zaidul I S M, Norulain N A N, Omar A K M, Yamauchi H, Noda T. RVA analysis of mixtures of wheat flour and potato, sweet potato, yam, and cassava starches. Carbohydrate Polymers, 2007, 69(4): 784-791.
[27]   黄华宏. 甘薯淀粉理化特性研究[D]. 杭州: 浙江大学, 2002.
Huang H H. Physicochemical properties of sweet potato starch [D]. Hangzhou: Zhejiang University, 2002. (in Chinese)
[28]   谭仁祥. 植物成分分析. 北京: 科学出版社, 2002.
Tan R X. Analysis of Plant Ingredient. Beijing: Science Press, 2002. (in Chinese)
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