Improving bioethanol yield: The use of solid-state fermentation products grown on DDGS

Abstract

In a climate of uncertain prices for grain and fuel, conservation and efficiency are more important than ever. Many agro-industrial residues are excellent substrates for solid-state fermentation (SSF). Dried distillers grains with solubles (DDGS) are an important co-product of the ethanol industry and have potential as a substrate for solid-state fermentation. SSF products were produced using DDGS from a distillery and DDGS from a fuel ethanol plant as the fungal growth substrate. The spent grains were inoculated with GRAS (Generally Regarded As Safe) organisms Aspergillus orzyae and Rhizopus oligosporus. After growth, the resultant SSF product was dried and used as an enzyme complex supplement that was added to laboratory scale standard fuel ethanol corn mash fermentations. Improved ethanol yields were consistently observed. The use of solid-state fermentation to produce unique enzyme complexes on DDGS offers a novel way to increase the value of the DDGS and to enhance bioethanol fermentation. © 2009 The Institute of Brewing & Distilling.