Grain sorghum fractionation in a modified dry grind ethanol process that includes production of an enriched protein fraction

Authors: Johnston, David

Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/2/2019
Publication Date: 6/30/2019
Citation: Johnston, D. 2019. Grain sorghum fermentation in a modified dry grind ethanol process that includes production of an enriched protein fraction. Cereal Chemistry. 96:920-926. https://doi.org/10.1002/cche.10195.
DOI: https://doi.org/10.1002/cche.10195

Interpretive Summary: Ethanol production currently relies almost exclusively on corn as the feedstock for production. Alternative feedstocks that have improved yields or drought tolerance could have a significant benefit by reducing the environmental impact on the ethanol production system. Grain sorghum could be an alternative feedstock for ethanol production providing it could be efficiently utilized in existing ethanol facilities. To help determine the potential, we utilized grain sorghum in a model ethanol process and compared this with the corn process. Additionally, we utilized an experimental fractionation process that produced an enriched protein fraction with the potential for diverse animal feed applications. The results show that utilizing grain sorghum can produce feed products with potentially higher value relative to corn. This information could be beneficial to ethanol producers as well as animal feed formulators interested in new feed formulations.

Technical Abstract: The dry grind ethanol process currently utilizes almost exclusively corn. The potential to utilize alternative feedstocks in existing corn based facilities is highly dependent on factors such as availability and cost but also on process compatibility and the impact on the coproducts. Grain sorghum is an alternative feedstock that has the potential to be widely utilized in existing facilities. In this study, grain sorghum was utilized for the production of ethanol and a post fermentation fraction process for the isolation of an enriched protein fraction was used and compared with conventional processing. The yield and compositional data for each fraction was calculated and an estimated economic value of each of the fractions was developed based on protein content. The protein fraction isolated contained 58.7% protein with less than 5% neutral detergent fiber. Estimated values for the modified fractions indicate a 46% improvement in potential coproduct value relative to conventional unfractionated corn based DDGS.