BioEnergy Research

, Volume 12, Issue 1, pp 94–102 | Cite as

Preheating Followed by Simultaneous Viscosity Reduction, Hydrolysis, and Fermentation: Simplifying the Process of Ethanol Production from Sweet Potato

  • Cristiane Martins Schweinberger
  • Jorge Otávio Trierweiler
  • Luciane Ferreira TrierweilerEmail author


In traditional methods, the ethanol production from starchy raw materials includes the stages of viscosity reduction, full hydrolysis, and fermentation, which are carried out in two or more steps. We propose to perform all these steps together with the method called P-SVHF (preheating followed by simultaneous viscosity reduction, hydrolysis, and fermentation). The sweet potato starch was hydrolyzed by applying a commercial enzyme mixture specially developed to degrade granular starch. Nevertheless, when starch was previously gelatinized, the ethanol production was 52% higher than that in which starch was in the granular form. Thus, the proposed method (P-SVHF) also includes the starch gelatinization stage (preheating). In the P-SVHF method, energy is saved through (i) reducing the mass that is heated (only sweet potatoes), and (ii) applying a temperature (76 °C) which is lower than what is usually used during the liquefaction (≥ 85 °C), then an energy saving of 48% in comparison with traditional methods was estimated. After the method definition, a central composite design was carried out to evaluate the influence of pH, temperature, and time in the SVHF. The significant contributions of the optimization were the time reduction, i.e., from 24 h to 18–19 h, and the ethanol conversion efficiency increased to about 93%.


Sweet potato Starch Ethanol Fermentation Optimization 



The authors would like to acknowledge the support from Coordination for the Improvement of Higher Education Personnel (CAPES) and the Federal University of Rio Grande do Sul (UFRGS); also, the authors would like to thank Tobias Romanzini Putti and Gabriela Baldin Susin for their collaboration in the experiment execution.

Compliance with Ethical Standards

Conflict of Interest

The authors declare that they have no conflict of interest.

Ethical Approval

This article does not contain any studies with human participants or animals performed by any of the authors.


  1. 1.
    Gupta A, Verma JP (2015) Sustainable bio-ethanol production from agro-residues: a review. Renew Sust Energ Rev 41(0):550–567. CrossRefGoogle Scholar
  2. 2.
    Srichuwong S, Orikasa T, Matsuki J, Shiina T, Kobayashi T, Tokuyasu K (2012) Sweet potato having a low temperature-gelatinizing starch as a promising feedstock for bioethanol production. Biomass Bioenergy 39:120–127CrossRefGoogle Scholar
  3. 3.
    Lareo C, Ferrari M, Guigou M, Fajardo L, Larnaudie V, Ramirez M, Martinez-Garreiro J (2013) Evaluation of sweet potato for fuel bioethanol production: hydrolysis and fermentation. SpringerPlus 2(1):493CrossRefGoogle Scholar
  4. 4.
    Betemps C, Pinto E (2016) Fepagro e Embrapa lançam nova cultivar de batata-doce na Expoagro. Embrapa. Accessed 11 abril 2016
  5. 5.
    de Castro LAS, Becker A (2011) Batata-doce BRS Amélia. Embrapa, PelotasGoogle Scholar
  6. 6.
    de Castro LAS, Becker A (2011) Batata-doce BRS Cuia. Embrapa, PelotasGoogle Scholar
  7. 7.
    de Castro LAS, Becker A (2011) Batata-doce BRS Rubissol. Embrapa, PelotasGoogle Scholar
  8. 8.
    Schweinberger CM (2016) Inovação e Otimização no Processo de Produção de Etanol a Partir de Batata-doce. PhD thesis in Chemical Engineering, Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre.
  9. 9.
    Martín JC, López E (2009) Modificación física del almidón de yuca y evaluación de la susceptilidad a la hidrólisis enzimática por una alfa amilasa. Rev Colomb Quím 38(3):395–408Google Scholar
  10. 10.
    Singh N, Singh J, Kaur L, Singh Sodhi N, Singh Gill B (2003) Morphological, thermal and rheological properties of starches from different botanical sources. Food Chem 81(2):219–231. CrossRefGoogle Scholar
  11. 11.
    Abegunde OK, Mu T-H, Chen J-W, Deng F-M (2013) Physicochemical characterization of sweet potato starches popularly used in Chinese starch industry. Food Hydrocoll 33(2):169–177. CrossRefGoogle Scholar
  12. 12.
    Cao Y, Tian H, Yao K, Yuan Y (2011) Simultaneous saccharification and fermentation of sweet potato powder for the production of ethanol under conditions of very high gravity. Front Chem Sci Eng 5(3):318–324CrossRefGoogle Scholar
  13. 13.
    Duvernay WH, Chinn MS, Yencho GC (2013) Hydrolysis and fermentation of sweetpotatoes for production of fermentable sugars and ethanol. Ind Crop Prod 42(1):527–537CrossRefGoogle Scholar
  14. 14.
    Zhang L, Zhao H, Gan M, Jin Y, Gao X, Chen Q, Guan J, Wang Z (2011) Application of simultaneous saccharification and fermentation (SSF) from viscosity reducing of raw sweet potato for bioethanol production at laboratory, pilot and industrial scales. Bioresour Technol 102(6):4573–4579. CrossRefGoogle Scholar
  15. 15.
    Robertson GH, Wong DWS, Lee CC, Wagschal K, Smith MR, Orts WJ (2005) Native or raw starch digestion: a key step in energy efficient biorefining of grain. J Agric Food Chem 54(2):353–365. CrossRefGoogle Scholar
  16. 16.
    Cinelli BA, Castilho LR, Freire DMG, Castro AM (2015) A brief review on the emerging technology of ethanol production by cold hydrolysis of raw starch. Fuel 150(Supplement C):721–729. CrossRefGoogle Scholar
  17. 17.
    Masiero SS, Peretti A, Trierweiler LF, Trierweiler JO (2014) Simultaneous cold hydrolysis and fermentation of fresh sweet potato. Biomass Bioenergy 70:174–183. CrossRefGoogle Scholar
  18. 18.
    Genencor (2009) STARGEN™ 002. Granular starch hydrolyzing enzyme for ethanol production. Danisco US Inc.Google Scholar
  19. 19.
    Novozymes (2009) Pectinex® ultra AFP. Product data sheet. NovozymesGoogle Scholar
  20. 20.
    Huang Y, Jin Y, Shen W, Fang Y, Zhang G, Zhao H (2014) 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. Biotechnol Appl Biochem 61(4):480–491. CrossRefGoogle Scholar
  21. 21.
    Oluwo AA, Khan RM, Salami MJE (2013) Effect of tuber skin on the thermal properties of whole tubers of potato and sweet potato. Paper presented at the IOP Conference Series: Materials Science and EngineeringGoogle Scholar
  22. 22.
    Novozymes (2011) Pectinex® Ultra AFP. Application sheet. Novozymes Switzerland AGGoogle Scholar
  23. 23.
    Angel (2015) Angel thermal resistance alcohol active dry yeast. ANGEL YEAST CO., LTD., HubeiGoogle Scholar
  24. 24.
    Bradbury JH, Holloway WD (1988) Chemistry or Tropical Root Crops: significance for nutrition and agriculture in the Pacific. ACIAR Monograph No. 6. Ramsay Ware Printing, MelbourneGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC, part of Springer Nature 2018

Authors and Affiliations

  • Cristiane Martins Schweinberger
    • 1
  • Jorge Otávio Trierweiler
    • 1
  • Luciane Ferreira Trierweiler
    • 1
    Email author
  1. 1.Department of Chemical EngineeringFederal University of Rio Grande do Sul (UFRGS)Porto AlegreBrazil

Personalised recommendations