Table of Contents
ISRN Microbiology
Volume 2012, Article ID 278092, 9 pages
http://dx.doi.org/10.5402/2012/278092
Research Article

Enzymatic Hydrolysis and Simultaneous Saccharification and Fermentation of Soybean Processing Intermediates for the Production of Ethanol and Concentration of Protein and Lipids

Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007, USA

Received 4 July 2012; Accepted 13 August 2012

Academic Editors: H. I. Atabay and K. Trulzsch

Copyright © 2012 Craig C. Long and William Gibbons. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Carbohydrates in soybeans are generally undesirable due to their low digestibility and because they “dilute” more valuable components (proteins, lipids). To remove these carbohydrates and raise the titer of more valuable components, ethanol production was investigated. Commercial enzymes (Novozyme cellulase, β-glucosidase, and pectinase) were added to ground soybeans (SB), soybean meal (SBM), soybean hulls (SH), and soybean white flakes (WF) at a 10% solids loading rate to quantify hydrolyzed glucan. Saccharification resulted in glucan reductions of 28%, 45%, 76%, and 80% (SBM, SB, SH, WF, resp.). Simultaneous saccharification and fermentation (SSF) trials were conducted at 5%, 10%, 15%, and 20% solids loading with Saccharomyces cerevisiae NRRL Y-2034 and Scheffersomyces stipitis NRRL Y-7124, with protein, fiber, and lipids analyzed at SSF 10% solids and saccharification trials. S. cerevisiae and S. stipitis produced ~3–12.5 g/L ethanol and ~2.5–8.6 g/L ethanol, respectively, on SB, SBM, and WF over all solid loading rates. SH resulted in higher ethanol titers for both S. cerevisiae (~9–23 g/L) and S. stipitis (~9.5–14.5 g/L). Protein concentrations decreased by 2.5–10% for the SB, SBM, and WF, but increased by 53%–55% in SH. Oil concentrations increased by ~50% for SB; by ~500%–1300% for the others.