Corn oil

Corn oil, in a 5-liter plastic bottle
Corn oil, plastic jugs in cardboard boxes, 33 lbs. each

Corn oil (maize oil) is oil extracted from the germ of corn (maize). Its main use is in cooking, where its high smoke point makes refined corn oil a valuable frying oil. It is also a key ingredient in some margarines. Corn oil is generally less expensive than most other types of vegetable oils. One bushel of corn contains 1.55 pounds of corn oil (2.8% by weight). Corn agronomists have developed high-oil varieties; however, these varieties tend to show lower field yields, so they are not universally accepted by growers.

Corn oil is also a feedstock used for biodiesel. Other industrial uses for corn oil include soap, salve, paint, rustproofing for metal surfaces, inks, textiles, nitroglycerin, and insecticides. It is sometimes used as a carrier for drug molecules in pharmaceutical preparations.

Production

Almost all corn oil is expeller-pressed, then solvent-extracted using hexane or 2-methylpentane (isohexane).[1] The solvent is evaporated from the corn oil, recovered, and re-used. After extraction, the corn oil is then refined by degumming and/or alkali treatment, both of which remove phosphatides. Alkali treatment also neutralizes free fatty acids and removes color (bleaching). Final steps in refining include winterization (the removal of waxes), and deodorization by steam distillation of the oil at 232–260 °C (450–500 °F) under a high vacuum.[1]

Some specialty oil producers manufacture unrefined, 100%-expeller-pressed corn oil. This is a more expensive product since it has a much lower yield than the combination expeller and solvent process, as well as a smaller market share.

Constituents and comparison

Vegetable oils
Type Processing
Treatment 		Saturated
fatty acids[2] 		Mono-
unsaturated
fatty acids[2] 		Polyunsaturated fatty acids Oleic acid
(ω-9)		Smoke point
Total poly[2] linolenic acid
(ω-3) 		Linoleic acid
(ω-6)
Avocado   11.560 70.554 13.486 1 12.5   249 °C (480 °F)[3]
Canola (rapeseed)   7.365 63.276 28.142 10 10   204 °C (400 °F)[4]
Coconut   91.000 6.000 3.000   2 6 177 °C (350 °F)[4]
Corn[5]   12.948 27.576 54.677 1 58 28 232 °C (450 °F)
Cottonseed   25.900 17.800 51.900 1 54 19 216 °C (420 °F)[5]
Flaxseed/Linseed (European)[6]   7.500 15.500 79.000 64 15 11 107 °C (225 °F)
Olive   14.000 72.000 14.000 1.5 15   193 °C (380 °F)[4]
Palm   49.300 37.000 9.300   10 40 235 °C (455 °F)
Peanut   16.900 46.200 32.000   32 48 225 °C (437 °F)[5]
Safflower (>70% linoleic)   8.000 15.000 75.000       210 °C (410 °F)[4]
Safflower (high oleic)   7.541 75.221 12.820       210 °C (410 °F)[4]
Soybean   15.650 22.783 57.740 7 50 24 238 °C (460 °F)[5]
Sunflower (<60% linoleic)   10.100 45.400 40.100 0.2 39.8 45.3 227 °C (440 °F)[5]
Sunflower (>70% oleic)   9.859 83.689 3.798       227 °C (440 °F)[5]
Cottonseed (hydrogenated)[2] Hydrogenated 93.600 1.529 0.587   0.287  
Palm (hydrogenated) Hydrogenated 47.500 40.600 7.500      
Soybean (hydrogenated)[2] Hydrogenated 21.100 73.700 0.400 0.096    
Values as percent (%) by weight of total fat.

Effects on health

Some medical research suggests that excessive levels of omega-6 fatty acids, relative to omega-3 fatty acids, may increase the probability of a number of diseases and depression.[7][8][9] Modern Western diets typically have ratios of omega-6 to omega-3 in excess of 10 to 1, some as high as 30 to 1, partly due to corn oil which has an omega-6 to omega-3 ratio of 49:1. The optimal ratio is thought to be 4 to 1 or lower.[10][11]

A high intake of omega-6 fatty acids may increase the likelihood that postmenopausal women will develop breast cancer.[12] Similar effects were observed on prostate cancer.[13] Other analysis suggested an inverse association between total polyunsaturated fatty acids and breast cancer risk.[14]

See also

References

  1. 1 2 Corn Refiners Association. Corn Oil 5th Edition. 2006
  2. 1 2 3 4 5 6 "Nutrient database, Release 24". United States Department of Agriculture. All values in this column are from the USDA Nutrient database unless otherwise cited.
  3. ↑ What is unrefined, extra virgin cold-pressed avocado oil?, The American Oil Chemists’ Society
  4. 1 2 3 4 5 Katragadda, H. R.; Fullana, A. S.; Sidhu, S.; Carbonell-Barrachina, Á. A. (2010). "Emissions of volatile aldehydes from heated cooking oils". Food Chemistry. 120: 59. doi:10.1016/j.foodchem.2009.09.070.
  5. 1 2 3 4 5 6 Wolke, Robert L. (May 16, 2007). "Where There's Smoke, There's a Fryer". The Washington Post. Retrieved March 5, 2011.
  6. ↑ Fatty acid composition of important plant and animal fats and oils (German) 21 December 2011, Hans-Jochen Fiebig, Münster
  7. ↑ Lands, William E.M. (December 2005). "Dietary fat and health: the evidence and the politics of prevention: careful use of dietary fats can improve life and prevent disease". Annals of the New York Academy of Sciences. Blackwell. 1055: 179–192. doi:10.1196/annals.1323.028. PMID 16387724.
  8. ↑ Hibbeln, Joseph R.; N; B; R; L; Nieminen, Levi R.G.; Blasbalg, Tanya L.; Riggs, Jessica A.; and Lands, William E.M. (June 1, 2006). "Healthy intakes of n−3 and n−6 fatty acids: estimations considering worldwide diversity". American Journal of Clinical Nutrition. American Society for Nutrition. 83 (6, supplement): 1483S–1493S. PMID 16841858.
  9. ↑ Okuyama, Hirohmi; Ichikawa, Yuko; Sun, Yueji; Hamazaki, Tomohito; Lands, William E.M. (2007). "ω3 fatty acids effectively prevent coronary heart disease and other late-onset diseases: the excessive linoleic acid syndrome". World Review of Nutritional Dietetics. World Review of Nutrition and Dietetics. Karger. 96 (Prevention of Coronary Heart Disease): 83–103. doi:10.1159/000097809. ISBN 3-8055-8179-3. PMID 17167282.
  10. ↑ Daley, C.A.; Abbott, A.; Doyle, P.; Nader, G.; Larson, S. (2004). "A literature review of the value-added nutrients found in grass-fed beef products". California State University, Chico (College of Agriculture). Retrieved 2008-03-23.
  11. ↑ Simopoulos, Artemis P. (October 2002). "The importance of the ratio of omega-6/omega-3 essential fatty acids". Biomedicine & Pharmacotherapy. 56 (8): 365–379. doi:10.1016/S0753-3322(02)00253-6. PMID 12442909.
  12. ↑ Emily Sonestedt; Ulrika Ericson; Bo Gullberg; Kerstin Skog; Håkan Olsson; Elisabet Wirfält (2008). "Do both heterocyclic amines and omega-6 polyunsaturated fatty acids contribute to the incidence of breast cancer in postmenopausal women of the Malmö diet and cancer cohort?". International Journal of Cancer. UICC International Union Against Cancer. 123 (7): 1637–1643. doi:10.1002/ijc.23394. PMID 18636564. Retrieved 2008-11-30.
  13. ↑ Yong Q. Chen; at al (2007). "Modulation of prostate cancer genetic risk by omega-3 and omega-6 fatty acids". The Journal of Clinical Investigation. 117 (7): 1866–1875. doi:10.1172/JCI31494. PMC 1890998Freely accessible. PMID 17607361.
  14. ↑ Valeria Pala; Vittorio Krogh; Paola Muti; Véronique Chajès; Elio Riboli; Andrea Micheli; Mitra Saadatian; Sabina Sieri; Franco Berrino (18 July 2001). "Erythrocyte Membrane Fatty Acids and Subsequent Breast Cancer: a Prospective Italian Study". JNCL. 93 (14): 1088–95. doi:10.1093/jnci/93.14.1088. PMID 11459870. Retrieved 2008-11-30.

Further reading

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