Industrial Crops and Products 33 (2011) 572–578 Contents lists available at ScienceDirect Industrial Crops and Products journal homepage: www.elsevier.com/locate/indcrop Composition and oxidative stability of crude oil extracts of corn germ and distillers grains  Jill K. Winkler-Moser a,∗ , Lotta Breyer b a USDA, Agricultural Research Service, National Center for Agricultural Utilization Research, Functional Foods Research, 1815 N University Street, Peoria, IL 61604, United States b POET Research, 4615 N. Lewis Ave, Sioux Falls, SD 57104, United States article info Article history: Received 1 September 2010 Received in revised form 3 December 2010 Accepted 8 December 2010 Available online 8 January 2011 Keywords: Corn Distillers grains DDGS Tocopherols Phytosterols Oxidation abstract The fatty acid composition, Acid Value, and the content and composition of tocopherols, tocotrienols, carotenoids, phytosterols, and steryl ferulates were determined in corn germ oil and four post- fermentation corn oils from the ethanol dry grind process. The oxidative stability index at 110 ◦ C was determined for the five oils, and four oils were compared for their stability during storage at 40 ◦ C as determined by peroxide value and hexanal content. The fatty acid composition of all five oils was typ- ical for corn oil. The Acid Value (and percentage of free fatty acids) was highest (28.3 mg KOH/g oil) in corn oil extracted centrifugally from a conventional dry grind ethanol processing facility and for oil extracted, using hexane, from distillers dried grains with solubles (DDGS) from a raw starch ethanol processing facility (20.8 mg KOH/g oil). Acid Value was lowest in two oils extracted centrifugally from thin stillage in a raw starch ethanol facility (5.7 and 6.9 mg KOH/g oil). Tocopherols were highest in corn germ oil (∼1400 g/g), but tocotrienols, phytosterols, steryl ferulates, and carotenoids were higher in all of the post-fermentation corn oils. Hexane extracted oil from DDGS was the most oxidatively stable as evaluated by OSI and storage test at 40 ◦ C, followed by centrifugally extracted thin stillage oil from the raw starch ethanol process, and centrifugally extracted thin stillage oil from the conventional dry grind ethanol process. Corn germ oil was the least oxidatively stable. When stored at room temperature, the peroxide value of centrifugally extracted thin stillage oil from the raw starch ethanol process did not significantly increase until after six weeks of storage, and was less than 2.0 mequiv. peroxide/kg oil after three months of storage. These results indicate that post-fermentation corn oils have higher content of valuable functional lipids than corn germ oil. Some of these functional lipids have antioxidant activity which increases the oxidative stability of the post-fermentation oils. Published by Elsevier B.V. 1. Introduction Over 10 billion gallons of ethanol were produced from corn in the U.S. in 2009 (U.S. Energy Information Administration, 2010), generating over 25 million metric tons of corn distillers dried grains with solubles (DDGS) as a co-product of the dry grind ethanol process. DDGS is mainly sold as animal feed, and because increas- ing ethanol production could cause overproduction of DDGS and resulting lower prices, the ethanol industry is interested in other potential co-products from the dry grind process. One potential co- product is corn oil, which traditionally is extracted, using hexane,  Mention of trade names or commercial products in this publication is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture. USDA is an equal opportunity provider and employer. ∗ Corresponding author. Tel.: +1 309 681 6390; fax: +1 309 681 6685. E-mail address: Jill.Moser@ars.usda.gov (J.K. Winkler-Moser). from corn germ isolated during corn wet-milling. Two strategies for removing the corn oil include fractionating the corn prior to fermentation to remove the germ for oil extraction, or removing the oil post-fermentation from either the whole or thin stillage (Watkins, 2007). Oil removed at the front end has potential for sale as corn oil for human consumption; oil removed from the back end (post-fermentation) could be used as a feedstock for biodiesel pro- duction, for commercial feed production, or potentially for human consumption if the ethanol plant and process were food-grade, or if the oil was further refined to meet food grade oil quality require- ments. There is also interest in fractionating the oil to obtain the functional lipids including tocols (tocopherols and tocotrienols), phytosterols, and carotenoids (Winkler-Moser and Vaughn, 2009; Moreau et al., 2010). In the conventional dry-grind ethanol process (Fig. 1A), whole corn is ground to a flour, mixed with water and cooked at a high temperature to gelatinize the starch and to make it more available for subsequent liquification and saccharification by enzymes. The cooked mash is then cooled to facilitate fermentation of the sug- 0926-6690/$ – see front matter Published by Elsevier B.V. doi:10.1016/j.indcrop.2010.12.013