Corn oil
Encyclopedia
Corn 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 margarine
s. 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, ink
s, textile
s, nitroglycerin, and insecticide
s. It is sometimes used as a carrier for drug molecules in pharmaceutical
preparations.
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 smaller market share.
, with proportions of approximately 55% polyunsaturated fatty acid
, 30% monounsaturated fatty acid, and 15% saturated fatty acid.
s, may increase the probability of a number of diseases and depression.
A high intake of omega-6 fatty acids may increase the likelihood that postmenopausal women will develop breast cancer
. Similar effect were observed on prostate cancer
. Other analysis suggested an inverse association between total polyunsaturated fatty acids and breast cancer risk.
Oil
An oil is any substance that is liquid at ambient temperatures and does not mix with water but may mix with other oils and organic solvents. This general definition includes vegetable oils, volatile essential oils, petrochemical oils, and synthetic oils....
extracted from the germ
Cereal germ
The germ of a cereal is the reproductive part that germinates to grow into a plant; it is the embryo of the seed. Along with bran, germ is often a by-product of the milling that produces refined grain products. Cereal grains and their components, such as wheat germ, rice bran, and maize may be used...
of corn (maize
Maize
Maize known in many English-speaking countries as corn or mielie/mealie, is a grain domesticated by indigenous peoples in Mesoamerica in prehistoric times. The leafy stalk produces ears which contain seeds called kernels. Though technically a grain, maize kernels are used in cooking as a vegetable...
). Its main use is in cooking, where its high smoke point
Smoke point
The smoke point generally refers to the temperature at which a cooking fat or oil begins to break down to glycerol and free fatty acids, and produce bluish smoke. The glycerol is then further broken down to acrolein which is a component of the smoke. It is the presence of the acrolein that causes...
makes refined corn oil a valuable frying
Frying
Frying is the cooking of food in oil or another fat, a technique that originated in ancient Egypt around 2500 BC. Chemically, oils and fats are the same, differing only in melting point, but the distinction is only made when needed. In commerce, many fats are called oils by custom, e.g...
oil. It is also a key ingredient in some margarine
Margarine
Margarine , as a generic term, can indicate any of a wide range of butter substitutes, typically composed of vegetable oils. In many parts of the world, the market share of margarine and spreads has overtaken that of butter...
s. Corn oil is generally less expensive than most other types of vegetable oils. One bushel
Bushel
A bushel is an imperial and U.S. customary unit of dry volume, equivalent in each of these systems to 4 pecks or 8 gallons. It is used for volumes of dry commodities , most often in agriculture...
of corn contains 1.55 pounds
Pound (mass)
The pound or pound-mass is a unit of mass used in the Imperial, United States customary and other systems of measurement...
of corn oil (2.8% by weight). Corn agronomists
Agricultural science
Agricultural science is a broad multidisciplinary field that encompasses the parts of exact, natural, economic and social sciences that are used in the practice and understanding of agriculture. -Agriculture and agricultural science:The two terms are often confused...
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
Biodiesel
Biodiesel refers to a vegetable oil- or animal fat-based diesel fuel consisting of long-chain alkyl esters. Biodiesel is typically made by chemically reacting lipids with an alcohol....
. Other industrial uses for corn oil include soap
Soap
In chemistry, soap is a salt of a fatty acid.IUPAC. "" Compendium of Chemical Terminology, 2nd ed. . Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications, Oxford . XML on-line corrected version: created by M. Nic, J. Jirat, B. Kosata; updates compiled by A. Jenkins. ISBN...
, salve
Salve
A salve is a medical ointment used to soothe the head or other body surface. A popular eye medicine known as "Phrygian powder" was one of Laodicea's sources of wealth...
, paint
Paint
Paint is any liquid, liquefiable, or mastic composition which after application to a substrate in a thin layer is converted to an opaque solid film. One may also consider the digital mimicry thereof...
, rustproofing
Rustproofing
Rustproofing is a condition of preservation or protection, by a process or treatment whereby the rate at which objects made of iron and/or steel begin to rust is reduced. The degradation in the long term can not be stopped completely, unless the rustproofing is periodically renewed...
for metal surfaces, ink
Ink
Ink is a liquid or paste that contains pigments and/or dyes and is used to color a surface to produce an image, text, or design. Ink is used for drawing and/or writing with a pen, brush, or quill...
s, textile
Textile
A textile or cloth is a flexible woven material consisting of a network of natural or artificial fibres often referred to as thread or yarn. Yarn is produced by spinning raw fibres of wool, flax, cotton, or other material to produce long strands...
s, nitroglycerin, and insecticide
Insecticide
An insecticide is a pesticide used against insects. They include ovicides and larvicides used against the eggs and larvae of insects respectively. Insecticides are used in agriculture, medicine, industry and the household. The use of insecticides is believed to be one of the major factors behind...
s. It is sometimes used as a carrier for drug molecules in pharmaceutical
Pharmacology
Pharmacology is the branch of medicine and biology concerned with the study of drug action. More specifically, it is the study of the interactions that occur between a living organism and chemicals that affect normal or abnormal biochemical function...
preparations.
Production
Almost all corn oil is expeller pressed, then solvent extracted using hexane or isohexane. 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 - 260C (450 - 500F) under a high vacuum.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 smaller market share.
Constituents
Refined corn oil is 99% triglycerideTriglyceride
A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....
, with proportions of approximately 55% polyunsaturated fatty acid
Fatty acid
In chemistry, especially biochemistry, a fatty acid is a carboxylic acid with a long unbranched aliphatic tail , which is either saturated or unsaturated. Most naturally occurring fatty acids have a chain of an even number of carbon atoms, from 4 to 28. Fatty acids are usually derived from...
, 30% monounsaturated fatty acid, and 15% saturated fatty acid.
- Of the saturated fatty acids, 80% are palmitic acidPalmitic acidPalmitic acid, or hexadecanoic acid in IUPAC nomenclature, is one of the most common saturated fatty acids found in animals and plants. Its molecular formula is CH314CO2H. As its name indicates, it is a major component of the oil from palm trees . Palmitate is a term for the salts and esters of...
(lipid number of C16:0), 14% stearic acidStearic acidStearic acid is the saturated fatty acid with an 18 carbon chain and has the IUPAC name octadecanoic acid. It is a waxy solid, and its chemical formula is CH316CO2H. Its name comes from the Greek word στέαρ "stéatos", which means tallow. The salts and esters of stearic acid are called stearates...
(C18:0), and 3% arachidic acidArachidic acidArachidic acid, also called eicosanoic acid, is the saturated fatty acid with a 20 carbon chain. It is as a minor constituent of peanut oil and corn oil . Its name derives from the Latin arachis — peanut...
(C20:0). - Over 99% of the monounsaturated fatty acids are oleic acidOleic acidOleic acid is a monounsaturated omega-9 fatty acid found in various animal and vegetable fats. It has the formula CH37CH=CH7COOH. It is an odorless, colourless oil, although commercial samples may be yellowish. The trans isomer of oleic acid is called elaidic acid...
(C18:1 c) - 98% of the polyunsaturated fatty acids are the omega-6 linoleic acidLinoleic acidLinoleic acid is an unsaturated n-6 fatty acid. It is a colorless liquid at room temperature. In physiological literature, it has a lipid number of 18:2...
(C18:2 n-6 c,c) with the 2% remainder being the omega-3 alpha-linolenic acidAlpha-linolenic acidα-Linolenic acid is an organic compound found in many common vegetable oils. In terms of its structure, it is named all-cis-9,12,15-octadecatrienoic acid. In physiological literature, it is given the name 18:3 ....
(C18:3 n-3 c,c,c).
Negative health effects
Some medical research suggests that excessive levels of omega-6 fatty acids, relative to omega-3 fatty acidOmega-3 fatty acid
N−3 fatty acids are essential unsaturated fatty acids with a double bond starting after the third carbon atom from the end of the carbon chain....
s, may increase the probability of a number of diseases and depression.
A high intake of omega-6 fatty acids may increase the likelihood that postmenopausal women will develop breast cancer
Breast cancer
Breast cancer is cancer originating from breast tissue, most commonly from the inner lining of milk ducts or the lobules that supply the ducts with milk. Cancers originating from ducts are known as ductal carcinomas; those originating from lobules are known as lobular carcinomas...
. Similar effect were observed on prostate cancer
Prostate cancer
Prostate cancer is a form of cancer that develops in the prostate, a gland in the male reproductive system. Most prostate cancers are slow growing; however, there are cases of aggressive prostate cancers. The cancer cells may metastasize from the prostate to other parts of the body, particularly...
. Other analysis suggested an inverse association between total polyunsaturated fatty acids and breast cancer risk.