DOI: 10.1094/CC-83-0569 |  VIEW ARTICLE

Effects of Amylose, Corn Protein, and Corn Fiber Contents on Production of Ethanol from Starch-Rich Media (1).

X. Wu (2), R. Zhao (2), D. Wang (2,3), S. R. Bean (4), P. A. Seib (5), M. R. Tuinstra (6), M. Campbell (6), and A. O’Brien (7). (1) Contribution No 06-173-J from the Kansas Agricultural Experiment Station, Manhattan, KS 66506. (2) Department of Biological and Agricultural Engineering, Kansas State University, Manhattan, KS 66506. (3) Corresponding author. Phone: 785-532-2919, Fax: 785-532-5825. Email: <dwang@ksu.edu> (4) USDA-ARS Grain Marketing & Production Research Center, Manhattan, KS 66502. Names are necessary to report factually on available data; however, the USDA neither guarantees nor warrants the standard of the product, and the use of the name by the USDA implies no approval of the product to the exclusion of others that may also be suitable. (5) Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506. (6) Department of Agronomy, Kansas State University, Manhattan, KS 66506. (7) Science Division, Truman State University, Kirksville, MO 63501. Cereal Chem. 83(5):569-575. Accepted July 14, 2006. This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. AACC International, Inc., 2006.

The effects of amylose, protein, and fiber contents on ethanol yields were evaluated using artificially formulated media made from commercial corn starches with different contents of amylose, corn protein, and corn fiber, as well as media made from different cereal sources including corn, sorghum, and wheat with different amylose contents. Second-order response-surface regression models were used to study the effects and interactions of amylose, protein, and fiber contents on ethanol yield and conversion efficiency. The results showed that the amylose content of starches had a significant (P < 0.001) effect on ethanol conversion efficiency. No significant effect of protein content on ethanol production was observed. Fiber did not show a significant effect on ethanol fermentation either. Conversion efficiencies increased as the amylose content decreased, especially when the amylose content was >35%. The reduced quadratic model fits the conversion efficiency data better than the full quadratic model does. Fermentation tests on mashes made from corn, sorghum, and wheat samples with different amylose contents confirmed the adverse effect of amylose content on fermentation efficiency. High-temperature cooking with agitation significantly increased the conversion efficiencies on mashes made from high-amylose (35–70%) ground corn and starches. A cooking temperature of >160°C was needed on high-amylose corn and starches to obtain a conversion efficiency equal to that of normal corn and starch.