Plant oils
Encyclopedia
Plant oils or vegetable oils are oil
s derived from plant sources, as opposed to animal fat
s or petroleum
. There are three primary types of plant oil, differing both the means of extracting the relevant parts of the plant, and in the nature of the resulting oil:
are what are most commonly called vegetable oils. These are triglyceride
-based, and include cooking oils like canola oil, solid oils like cocoa butter
, oils used in paint
like linseed oil
and oils used for industrial purposes. Pressed vegetable oils are extracted from the plant containing the oil (usually the seed), using one of two types of oil press. The most common is the screw press, which consists of a large-diameter metal screw inside a metal housing. Oil seeds are fed into the housing, where the screws mash the seeds, and create pressure which forces the oil out through small holes in the side of the press. The remaining solids, called seed cake, are either discarded or used for other purposes. Oil presses can be either manual or powered. The second type of oil press is the ram press, where a piston is driven into a cylinder, crushing the seeds and forcing out the oil. Ram presses are generally more efficient than screw presses.
There has been recent interest in improving the design of mechanical oil presses, particularly for use in developing countries. A press developed at MIT's D-Lab, for example, is capable of exerting 800-1,000psi to extract peanut oil.
Industrial machines for extracting oil mechanically are call expellers. Many expellers add heat and pressure, in order to increase the amount of oil extracted. If the temperature does not exceed 120°F, the oil can be called "cold-pressed".
In modern vegetable oil production, oils are usually extracted chemically, using a solvent
such as hexane
. Chemical extraction is cheaper and more efficient than mechanical extraction, at a large scale, leaving only 0.5-0.7% of the oil in the plant solids, as compared to 6-14% for mechanical extraction.
s are not oils but volatile aromatic compounds that are used in flavors, fragrances, and in aroma therapy for health purposes. Essential oils are usually extracted by distillation
.
Maceration is also used as a means of extracting essential oils. In this process, used, for example, to extract the onion, garlic, wintergreen and bitter almond essential oil, the plant material is macerated in warm water to release the volatile compounds in the plant.
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....
s derived from plant sources, as opposed to animal fat
Animal fat
Animal fats are rendered tissue fats that can be obtained from a variety of animals.- Pet nutrition :In pet nutrition, the source of animal fat concerns food manufacturers. AAFCO states that animal fat is "obtained from the tissues of mammals and/or poultry in the commercial processes of rendering...
s or petroleum
Petroleum
Petroleum or crude oil is a naturally occurring, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights and other liquid organic compounds, that are found in geologic formations beneath the Earth's surface. Petroleum is recovered mostly through oil drilling...
. There are three primary types of plant oil, differing both the means of extracting the relevant parts of the plant, and in the nature of the resulting oil:
- Vegetable fats and oilsVegetable fats and oilsVegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides, as contrasted with waxes which lack glycerin in their structure...
were historically extracted by putting part of the plant under pressurePressurePressure is the force per unit area applied in a direction perpendicular to the surface of an object. Gauge pressure is the pressure relative to the local atmospheric or ambient pressure.- Definition :...
, squeezing out the oil. - Macerated oils consist of a base oil to which parts of plants are added.
- Essential oilEssential oilAn essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...
s are composed of volatile aromatic compounds, extracted from plants by distillationDistillationDistillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
.
Vegetable fats and oils
Vegetable fats and oilsVegetable fats and oils
Vegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides, as contrasted with waxes which lack glycerin in their structure...
are what are most commonly called vegetable oils. These are triglyceride
Triglyceride
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....
-based, and include cooking oils like canola oil, solid oils like cocoa butter
Cocoa butter
Cocoa butter, also called theobroma oil, is a pale-yellow, pure edible vegetable fat extracted from the cocoa bean. It is used to make chocolate, biscuits, and baked goods, as well as some pharmaceuticals, ointments, and toiletries...
, oils used in 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...
like linseed oil
Linseed oil
Linseed oil, also known as flaxseed oil, is a clear to yellowish oil obtained from the dried ripe seeds of the flax plant . The oil is obtained by cold pressing, sometimes followed by solvent extraction...
and oils used for industrial purposes. Pressed vegetable oils are extracted from the plant containing the oil (usually the seed), using one of two types of oil press. The most common is the screw press, which consists of a large-diameter metal screw inside a metal housing. Oil seeds are fed into the housing, where the screws mash the seeds, and create pressure which forces the oil out through small holes in the side of the press. The remaining solids, called seed cake, are either discarded or used for other purposes. Oil presses can be either manual or powered. The second type of oil press is the ram press, where a piston is driven into a cylinder, crushing the seeds and forcing out the oil. Ram presses are generally more efficient than screw presses.
There has been recent interest in improving the design of mechanical oil presses, particularly for use in developing countries. A press developed at MIT's D-Lab, for example, is capable of exerting 800-1,000psi to extract peanut oil.
Industrial machines for extracting oil mechanically are call expellers. Many expellers add heat and pressure, in order to increase the amount of oil extracted. If the temperature does not exceed 120°F, the oil can be called "cold-pressed".
In modern vegetable oil production, oils are usually extracted chemically, using a solvent
Solvent
A solvent is a liquid, solid, or gas that dissolves another solid, liquid, or gaseous solute, resulting in a solution that is soluble in a certain volume of solvent at a specified temperature...
such as hexane
Hexane
Hexane is a hydrocarbon with the chemical formula C6H14; that is, an alkane with six carbon atoms.The term may refer to any of four other structural isomers with that formula, or to a mixture of them. In the IUPAC nomenclature, however, hexane is the unbranched isomer ; the other four structures...
. Chemical extraction is cheaper and more efficient than mechanical extraction, at a large scale, leaving only 0.5-0.7% of the oil in the plant solids, as compared to 6-14% for mechanical extraction.
Macerated oils
Macerated or infused oils are oils to which other matter has been added, such as herbs or flowers. Typically, the oil used is a food-grade fat-type oil.Essential oils
Essential oilEssential oil
An essential oil is a concentrated hydrophobic liquid containing volatile aroma compounds from plants. Essential oils are also known as volatile oils, ethereal oils or aetherolea, or simply as the "oil of" the plant from which they were extracted, such as oil of clove...
s are not oils but volatile aromatic compounds that are used in flavors, fragrances, and in aroma therapy for health purposes. Essential oils are usually extracted by distillation
Distillation
Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture. Distillation is a unit operation, or a physical separation process, and not a chemical reaction....
.
Maceration is also used as a means of extracting essential oils. In this process, used, for example, to extract the onion, garlic, wintergreen and bitter almond essential oil, the plant material is macerated in warm water to release the volatile compounds in the plant.
See also
- TriglycerideTriglycerideA 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....
- Vegetable fats and oilsVegetable fats and oilsVegetable fats and oils are lipid materials derived from plants. Physically, oils are liquid at room temperature, and fats are solid. Chemically, both fats and oils are composed of triglycerides, as contrasted with waxes which lack glycerin in their structure...
- List of vegetable oils
- List of essential oils