Harnessing the pressure-tunable properties of liquid propane for extracting corn kernel oil: Experimental and technoeconomic assessments

Ethanol production from corn has evolved to improve process efficiency and generate valuable coproducts. Currently, corn oil is directed for animal feed as part of distiller's dried grains and soluble (DDGS) or for biodiesel production, but a higher value could be derived from purified oil for human consumption. This study investigates the integration of a pressurized liquid propane-based corn kernel oil extraction step into the dry milling process, allowing the remaining solids to be utilized for ethanol fermentation. Comparative extractions using ethanol, hexane, and propane were conducted on ground corn at a solvent-to-solid ratio of 4 mL/g. Oil yields were 98.2 ± 0.09 % for ethanol, 94.2 ± 0.01 % for hexane, and 76.86 ± 0.14 % for pressurized propane. A techno-economic analysis of corn kernel oil extraction was performed for a 100-million-gallon-per-year ethanol plant. While the propane-based extraction process incurred lower oil yield, it exhibited lower annual operating expenses ($243.64 million) - 36 % lower than ethanol and 27 % lower than hexane, primarily due to reduced raw material costs and energy consumption, leading to higher profitability. Sensitivity analysis on solvent recycling efficiency indicated that propane achieved breakeven profitability at 97 % recycling. These findings highlight the potential of propane as a food-grade, recyclable solvent with economic and process integration benefits for corn ethanol biorefineries. Despite its lower oil yield, propane's operational advantages present a compelling pathway towards cost-effective, multi-product facilities. • Experimental and simulation-based extraction of edible corn oil from dry-grind corn. • Comparative analysis of ethanol, hexane, and propane as extraction solvents. • Process flowsheet includes pretreatment, extraction, and separation steps. • Propane achieved breakeven profitability at 97 % compared to other solvents.