Vegetable oils, or vegetable fats, are oils extracted from seeds or from other parts of edible plants. Like animal fats, vegetable fats are mixtures of triglycerides. Soybean oil, canola oil, grapeseed oil, and cocoa butter are examples of seed oils, or fats from seeds. Olive oil, palm oil, and rice bran oil are examples of fats from other parts of plants. In common usage, vegetable oil may refer exclusively to vegetable fats which are liquid at room temperature. Vegetable oils are usually edible and are generally recognized as safe (GRAS) by the United States Food and Drug Administration (FDA). There is no evidence that seed oils are unhealthy.
Vegetable oils have been used for thousands of years (dating back to at least 6000 BC for olive oil) and were historically important for cooking, lighting, medicine, and industry. Palm oil later becoming a major global commodity during the Industrial Revolution. In the 19th and 20th centuries, scientific advances (like understanding fats and hydrogenation) led to modern products such as margarine and shortening. Oils like soybean and canola became dominant in global markets. Today, vegetable oils are widely used in food, manufacturing (e.g., cosmetics, paints, lubricants), and biofuel, and are produced mainly by pressing or chemical extraction. Global output is rising significantly due to demand, especially for palm oil.
History
In antiquity Olive oil has been a part of human culture for millennia.Ruth Schuster (December 17, 2014). "8,000-year old olive oil found in Galilee, earliest known in world", Haaretz. Retrieved December 17, 2014. Archaeological evidence shows that olives were turned into olive oil by 6000 BC and 4500 BC in present-day Israel.Ehud Galili et al., "Evidence for Earliest Olive-Oil Production in Submerged Settlements off the Carmel Coast, Israel", Journal of Archaeological Science 24:1141–1150 (1997) Pagnol, p. 19, says the 6th millennium in Jericho, but cites no source. In ancient Egypt, plant oils including cedar oil, cypress oil, and olive oil were used during the mummification process.
Vegetable oils have been used as lighting fuel for lamps, cooking, medicine and lubrication. Palm oil has long been recognized in West and Central African countries, and European merchants trading with West Africa occasionally purchased palm oil for use as a cooking oil in Europe. It became highly sought-after commodity by British traders for use as an industrial lubricant for machinery during Britain's Industrial Revolution.
Modern history Palm oil formed the basis of soap products, such as Lever Brothers' (now Unilever) "Sunlight", and B. J. Johnson Company's (now Colgate-Palmolive) "Palmolive", and by around 1870, palm oil constituted the primary export of some West African countries.Commercial Agriculture, the Slave Trade and Slavery in Atlantic Africa p. 22
In 1780, Carl Wilhelm Scheele demonstrated that fats were derived from glycerol. Thirty years later, Michel Eugène Chevreul deduced that these fats were esters of fatty acids and glycerol. Wilhelm Normann, a German chemist, introduced the hydrogenation of liquid fats in 1901, creating what later became known as trans fats, leading to the development of the global production of margarine and vegetable shortening.
In the United States, cottonseed oil was developed and marketed by Procter & Gamble as a creamed shortening – Crisco – as early as 1911. Ginning mills were happy to have someone haul away the cotton seeds. The extracted oil was refined and partially hydrogenated to give a solid at room temperature and thus mimic natural lard, and canned under nitrogen gas. Compared to the rendered lard Procter & Gamble was already selling to consumers, Crisco was cheaper, easier to stir into a recipe, and could be stored at room temperature for two years without turning rancid.
Soybeans are protein-rich, and the medium-viscosity oil rendered from them was high in polyunsaturates. Henry Ford established a soybean research laboratory, developed soybean plastics and a soy-based synthetic wool, and built a car "almost entirely" out of soybeans. Roger Drackett had a successful new product with Windex. He invested heavily in soybean research, seeing it as a smart investment. By the 1950s and 1960s, soybean oil had become the most popular vegetable oil in the US; today it is second only to palm oil. In 2018–2019, world production was at 57.4 MT with the leading producers including China (16.6 MT), US (10.9 MT), Argentina (8.4 MT), Brazil (8.2 MT), and EU (3.2 MT).
The early 20th century also saw the start of the use of vegetable oil as a fuel in diesel engines and in heating oil burners. Rudolf Diesel designed his engine to run on vegetable oil. The idea, he hoped, would make his engines more attractive to farmers who had a source of fuel readily available. Diesel's first engine ran on its own power for the first time in Augsburg, Germany, on 10 August 1893 on nothing but peanut oil. In remembrance of this event, 10 August has been declared "International Biodiesel Day". The first patent on Biodiesel was granted in 1937. Periodic petroleum shortages spurred research into vegetable oil as a diesel substitute during the 1930s and 1940s, and again in the 1970s and early 1980s when straight vegetable oil enjoyed its highest level of scientific interest. The 1970s also saw the formation of the first commercial enterprise to allow consumers to run straight vegetable oil in their vehicles. However, biodiesel, produced from oils or fats using transesterification is more widely used. Led by Brazil, many countries built biodiesel plants during the 1990s, and it is now widely available for use in motor vehicles, and is the most common biofuel in Europe today. In France, biodiesel is incorporated at a rate of 8% in the fuel used by all French diesel vehicles.
In the mid-1970s, Canadian researchers developed a low-erucic-acid rapeseed cultivar. Because the word "rape" was not considered optimal for marketing, they coined the name "canola" (from "Canada Oil low acid"). The U.S. Food and Drug Administration approved use of the canola name in January 1985, and U.S. farmers started planting large areas that spring. Canola oil is lower in saturated fats and higher in monounsaturates. Canola is very thin (unlike corn oil) and flavorless (unlike olive oil), so it largely succeeds by displacing soy oil, just as soy oil largely succeeded by displacing cottonseed oil.
The production of vegetable oils went up 125% between 2000 and 2020, driven by a sharp increase in palm oil. The global production of vegetable oils went up 130% between 2000 and 2022 to 212 million tonnes in 2022. This is 120 million tonnes more than in 2000, but 3 million tonnes less than the peak observed in 2021. Palm oil registered the largest increase, both absolute and relative, as its production went up 57 million tonnes, or 255%; it overtook soybean oil as the main vegetable oil produced in 2006.
Uses Culinary
Many vegetable oils are consumed directly, or indirectly as ingredients in food – a role that they share with some animal fats, including butter, ghee, lard, and schmaltz. The oils serve several purposes in this role: Shortening – as in giving pastries a crumbly texture. Enriching – adding calories and satisfaction in consumption Texture – altering how ingredients combine, especially fats and starches Flavoring – examples include olive, sesame, or almond oil Flavor base – oils can also "carry" flavors of other ingredients, such as peppers, since many flavors are due to chemicals that are soluble in oil.
Oils can be heated to temperatures significantly higher than the boiling point of water, , and used to fry foods. Oils for this purpose must have a high flash point. Such oils include both the major cooking oils – soybean, canola/rapeseed, sunflower, safflower, peanut, cottonseed, etc. – and tropical oils, such as coconut, palm, and rice bran. The latter are particularly valued in Asian cultures for high-temperature cooking, because of their unusually high flash points.
Industrial Vegetable oils are used as an ingredient or component in many manufactured products.
Many vegetable oils are used to make soaps, skin products, candles, perfumes, and other personal care and cosmetic products. Some oils are particularly suitable as drying oils, and are used in making paints and other wood treatment products. They are used in alkyd resin production. Dammar oil (a mixture of linseed oil and dammar resin), for example, is used almost exclusively in treating the hulls of wooden boats. Vegetable oils are increasingly being used in the electrical industry as insulators as vegetable oils are not toxic to the environment, biodegradable if spilled and have high flash and fire points. However, vegetable oils are less stable chemically, so they are generally used in systems where they are not exposed to oxygen, and they are more expensive than crude oil distillate. Synthetic tetraesters, which are similar to vegetable oils but with four fatty acid chains compared to the normal three found in a natural ester, are manufactured by Fischer esterification. Tetraesters generally have high stability to oxidation and have found use as engine lubricants. Vegetable oil is being used to produce biodegradable hydraulic fluid and lubricant.
One limiting factor in industrial uses of vegetable oils is that all such oils are susceptible to becoming rancid. Oils that are more stable, such as ben oil or mineral oil, are thus preferred for industrial uses. Castor oil has numerous industrial uses, owing to the presence of a hydroxyl group on the fatty acid. Castor oil is a precursor to Nylon 11. Castor oil may also be reacted with epichlorohydrin to make a glycidyl ether, which is used as a diluent and flexibilizer with epoxy resins.
Pet food additive Vegetable oil is used in the production of some pet foods. AAFCO defines vegetable oil in this context as the product of vegetable origin obtained by extracting the oil from seeds or fruits which are processed for edible purposes.
Fuel
Vegetable oils are also used to make biodiesel, which can be used like conventional diesel. Some vegetable oil blends are used in unmodified vehicles but straight vegetable oil, also known as pure plant oil, needs specially prepared vehicles which have a method of heating the oil to reduce its viscosity. The use of vegetable oils as alternative energy is growing and the availability of biodiesel around the world is increasing.
The NNFCC estimates that the total net greenhouse gas savings when using vegetable oils in place of fossil fuel-based alternatives for fuel production, range from 18 to 100%.National Non-Food Crops Centre. GHG Benefits from Use of Vegetable Oils for Electricity, Heat, Transport, and Industrial Purposes, NNFCC 10-016
Production
The production process of vegetable oil involves the removal of oil from plant components, typically seeds. This can be done via mechanical extraction using an oil mill or chemical extraction using a solvent. The extracted oil can then be purified and, if required, refined or chemically altered.
Mechanical extraction Oils can be removed via mechanical extraction, termed "crushing" or "pressing". This method is typically used to produce the more traditional oils (e.g., olive, coconut, etc.), and it is preferred by most health-food customers in the United States and in Europe. There are several different types of mechanical extraction. Expeller pressing extraction is common, though the screw press, ram press, and ghani (powered mortar and pestle) are also used. Oilseed presses are commonly used in developing countries, among people for whom other extraction methods would be prohibitively expensive; the ghani is primarily used in India. The amount of oil extracted using these methods varies widely, as shown in the following table for extracting mowrah butter in India:
Method Percentage extracted