A process for removing oil from an agricultural substrate, including a dry grind corn. An ethanol solution with a concentration in the range of from about 90% to about 100% ethanol is mixed with the dry grind corn in a ratio of from about 10:1 to about 1:1 to form an extraction solution including the ethanol solution, oil, and corn solids. The extraction solution is separated into the corn solids and a filtrate, the filtrate including the ethanol solution and oil. The filtrate is membrane filtered, including nanofiltration, to restrain an oil concentrate from the filtrate and pass a permeate of the ethanol solution. The oil contained within the oil concentrate is purified.