Grain sorghum fractionation in a modified dry grind ethanol process that includes production of an enriched protein fraction
2019
Johnston, David B.
BACKGROUND AND OBJECTIVES: 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 postfermentation fraction process for the isolation of an enriched protein fraction was used and compared with conventional processing. FINDINGS: The yield and compositional data for each fraction were 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. CONCLUSIONS: Utilization of grain sorghum in a dry grind ethanol process can produce DDGS that have a higher protein content relative to corn DDGS. Utilization of a postfermentation screening process followed by centrifugation of the stillage allowed for the recovery of an enriched protein fraction having minimal fiber content that would allow the protein fraction to be utilized in nonruminant animal feed diets. SIGNIFICANCE AND NOVELTY: Fractionation of grain sorghum in an ethanol process has not been previously reported in the literature.
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