Screening Sweetpotato Breeding Clones [Ipomoea batatas (L.) Lam] as a Suitable Potential Source of Feedstock for Bioethanol Production

Authors

  • Karine Z. Nyiawung University of Kentucky
  • Desmond G. Mortley Tuskegee University
  • Abukari Issah Mississippi State University
  • Marceline Egnin Tuskegee University
  • Conrad K. Bonsi Tuskegee University
  • Walter A. Hill Tuskegee University
  • Barrett T. Vaughan Tuskegee University

Keywords:

sweetpotato, fermentation, ethanol

Abstract

Experiments were conducted to evaluate white and orange fleshed sweetpotatoes as a feedstock for bioethanol production, based on dry matter (DM), extractable starch, amylose-amylopectin ratio, fermentation times and ethanol yields. Ten sweetpotato cultivars viz., W308, TU0002, WS149 05, BM8342119 TU090W009, DMOI158096, DMOI158204, TIB4008, TIB4085 and, Beauregard, were planted in replicated field variety trials. Plants were established from 30 cm long vine cuttings and N was applied (P and K were sufficient) at 90 kg ha-1 based on soil test recommendations. Twenty-four storage roots were collected from each cultivar at harvest, 120 days after planting, and randomly divided into three groups of eight which served as replicates. Samples were collected and contents of dry matter (DM), extractable starch and amylose/amylopectin were determined. Ethanol (EtOH), concentration was determined by HPLC analysis from samples prepared using a solids:liquid ratio 0.13, which were hydrolyzed at 66°C for 90 min and fermented under anaerobic conditions using pure cells of Saccharomyces cerevisiae (yeast) at 30°C for 20 or 40 h. DM ranged from 19.6 to 35.9% and extractable starch from 10.9 to 25.3%, for Beauregard and W308, respectively. Amylose/amylopectin ranged from 19.5% for BM8342119 to 30.8% for TU0002, with ratios of 0.24 and 0.46, respectively. EtOH content ranged from 34.4 g L-1 for Beauregard to 66.6 g L-1 for TIB085 at 20 h and from 34.0 g L-1 for Beauregard to 71.0 g L-1 for TIB085 at 40 h of fermentation time. Increases in EtOH content with an additional 20 h fermentation time ranged from marginal to 9.0 g L-1. Significant correlations existed between DM and EtOH, and starch and EtOH. These data suggest that seven of the sweetpotato cultivars can serve as potential feedstocks for bioethanol production, the higher the DM and starch, the greater the yield and a 40 h fermentation time will increase production.
Keywords: Sweetpotato, Alternative Energy, Fermentation

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Published

2014-11-06

Issue

Vol. 5 No. 3 (2014)

Section

Research Article

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