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Title: RECOVERY OF CORN OIL FROM ETHANOL EXTRACTS OF GROUND CORN USING MEMBRANE TECHNOLOGY

Author
item Kwiatkowski, Jason
item CHERYAN, MUNIR - UNIV. OF ILLINOIS

Submitted to: Journal of the American Oil Chemists' Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/14/2005
Publication Date: 3/1/2005
Citation: Kwiatkowski, J.R., Cheryan, M. 2005.Recovery of corn oil from ethanol extracts of ground corn using membrane technology. Journal of the American Oil Chemists' Society, V. 82, No. 3 p.221-227.

Interpretive Summary: The generation and recovery of additional products along with the production of ethanol increases the value of a corn kernel using the dry-grind process. Methods have been developed previously to add value by extracting corn oil using ethanol, which is already produced during the process. Corn oil, which typically passes through the process without participating in any reactions, could be recovered and sold to increase the revenue of the process as a whole. The method used here aims to purify the extracted corn oil using membrane filtration. Separation of the corn oil from the ethanol using synthetic membrane filters generates corn oil as a product while also recovering the ethanol used in extraction. Other valuable products may also be concentrated during the filtration step. Studies using ideal solutions of corn oil in ethanol and actual liquid extracts show a marked increase in corn oil concentration with processing. This information will be useful to those trying to design a plant and commercialize this new, lower cost membrane process for making corn oil.

Technical Abstract: The recovery of additional co-products from the dry-grind process for ethanol could impact the industry greatly, as most facilities today rely on subsidies and tax incentives to operate. Modification of the process to include the extraction of oil could add $0.30-0.50 per bushel to the value derived from corn. A process combining solvent extraction with membrane technology to recover the oil was investigated. To evaluate the feasibility of this process, several nanofiltration membranes were tested for their stability in ethanol. Each of the membranes was conditioned with solutions of water:ethanol (0-100 v/v%) and the top three were chosen based on their performance with respect to flux and rejection. Beginning at 5 g/L, solutions of corn oil in ethanol were concentrated to over 100 g/L with the DK, TFC-SR1, and TFC-SR2 membranes. The liquid extract was then similarly concentrated, yielding a retentate fraction that was highly concentrated with solids in addition to corn oil, such as protein (zein), lecithins and other potentially high-value fractions soluble in ethanol. Analysis of the extract retentate showed a significant increase in oil concentration with increasing volume concentration ratio, indicating that pure ethanol extracts of corn may be successfully concentrated using nanofiltration membranes.