African Journal of
Biotechnology

  • Abbreviation: Afr. J. Biotechnol.
  • Language: English
  • ISSN: 1684-5315
  • DOI: 10.5897/AJB
  • Start Year: 2002
  • Published Articles: 12258

Full Length Research Paper

Evaluation of ethanol production from pito mash using Zymomonas mobilis and Saccharomyces cerevisiae

Ofosu-Appiah C.*
  • Ofosu-Appiah C.*
  • Department of Biochemistry and Biotechnology, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
  • Google Scholar
Zakpaa H. D.
  • Zakpaa H. D.
  • Department of Biochemistry and Biotechnology, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
  • Google Scholar
Mak-Mensah E.
  • Mak-Mensah E.
  • Department of Biochemistry and Biotechnology, College of Science, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
  • Google Scholar
Bentil J. A.
  • Bentil J. A.
  • Department of Chemical and Biochemical Engineering, Center for Bioprocessing Engineering, Technical University of Denmark, Lyngby, Denmark.
  • Google Scholar


  •  Received: 12 October 2015
  •  Accepted: 30 June 2016
  •  Published: 27 July 2016

Abstract

This study investigated the potential of pito mash (waste from sorghum brewing) as alternative and cost-effective feedstock for bioethanol production by means of fermentation using Zymomonas mobilis and Saccharomyces cerevisiae isolated from freshly tapped palm wine. Fermentation parameters such as pH, temperature and incubation period were studied. The fermentation microbes, Z. mobilis and S. cerevisiae were identified using APITM test kit and morphological characteristics, respectively. Analysis of reducing sugar residue was performed using dinitrosalicylic acid (DNS) method, while analysis of ethanol content was performed using gas chromatography. Pito mash recorded total starch content of 6.69%, reducing sugar content of 11.1 mg ml-1 and cellulose content of 0.41 mg g-1. Saccharification by malting increased reducing sugar content by 77.9% (19.75 mg ml-1). The optimum fermentation conditions (pH, temperature and incubation period) for Z. mobilis and S. cerevisiae were 5.5, 35°C, 3 days and 6.0, 30°C, 4 day, respectively. The maximum ethanol yield of 3.03 g l-1 and efficiency of 62% were obtained for S. cerevisiae while yield of 3.63 g l-1 and efficiency of 74.2% were obtained for Z. mobilis. Z. mobilis conclusively may be better organism for ethanol production from pito mash.

Key words: Pito mash, agro-industrial wastes, Zymomonas mobilis, ethanol, reducing sugars.