THE COMPOSITION OF CORN OIL OBTAINED BY THE ALCOHOL EXTRACTION OF GROUND CORN

Authors: Moreau, Robert; Hicks, Kevin

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/18/2005
Publication Date: 10/21/2005
Citation: Moreau, R.A., Hicks, K.B. 2005. The composition of corn oil obtained by the alcohol extraction of ground corn. Journal of the American Oil Chemists' Society. V. 82, No. 11. p. 809-815.

Interpretive Summary: Corn oil is a major edible oil, with a worldwide production of about 2 million tons. Essentially all of the corn oil produced in the US is obtained by hexane extraction of the germ portion of the corn kernel and the chemical composition of this oil has been well characterized. A promising new process has been developed to produce corn oil by extracting ground corn with a safer solvent, ethanol, but the chemical composition of this new type of corn oil is not known. The current study was undertaken to examine the chemical composition of this promising new type of corn oil and compare it with that of commercial corn oil. The results indicate that about 99% of the chemical components in ethanol-extracted corn kernel oil are identical to those found in commercial corn oil and about 1% are unique compounds. The chemical structures of three types of unique chemical compounds were identified for the first time in ethanol-extracted corn kernel oil. Before this new corn oil can be commercialized more needs to be known about the safety and health effects of these compounds. Also, studies need to be performed to evaluate the fate of these three unique compounds during standard vegetable oil refining. The commercial development of this new alternative process to obtain corn oil could benefit corn growers and corn millers. Also, if the unique compounds in this new type of corn oil are found to be health-promoting, it may justify a premium price and increased profits for producers of this new type of corn oil.

Technical Abstract: All commercial corn oil is obtained by the hexane extraction of corn germ and the chemical composition of this oil has been well characterized. With the current research interest in using alcohols to extract vegetable oils, this study was undertaken to quantitatively evaluate the lipid composition of corn oil obtained by the ethanol extraction of ground corn. When corn oil is obtained by extracting the corn kernels (ground corn) with polar or nonpolar solvents, the resulting corn oil contains much higher levels of hydroxycinnamate steryl esters (0.3%) than those found in commercial hexane-extracted corn (germ) oil (~0.02%). We previously reported that when corn oil was obtained by extracting corn kernels with polar solvents such as methylene chloride, the oil contained two polyamine conjugates, diferuloylputrescine and p-coumaroyl feruloylputrescine. In the current study, when ground corn was extracted with ethanol, the resulting corn oil was found to contain about 0.5% diferuloylputrescine and about 0.2% p coumaroylferuloylputrescine. For comparative purposes, the levels of these two polyamine conjugates were also measured in the oils obtained by extracting corn bran, dry milled corn germ, and wet milled corn germ with hexane, ethanol, and isopropanol, and they were detected in all of the oils obtained by extraction with either of the alcohols. Additional studies are needed to evaluate the health effects (benefits or toxicity) of hydroxycinnamate steryl esters and polyamine conjugates in ethanol-extracted corn kernel oil.