Vegetable oils, or vegetable fats, are fats extracted from seeds, or less often, from other parts of fruits. Like animal fats, vegetable fats are mixtures of triglycerides. Soybean oil, rapeseed oil, and cocoa butter are examples of fats from seeds. Olive oil, palm oil, and rice bran oil are example of fats from other parts of fruits. In common usage, vegetable oil may refer exclusively to vegetable fats which are liquid at room temperature.
Oils extracted from plants have been used since ancient times and in many cultures. As an example, in a 4,000-year-old kitchen unearthed in Indiana's Charlestown State Park, archaeologist Bob McCullough of Indiana University-Purdue University Fort Wayne found evidence that large slabs of rock were used to crush hickory nuts and the oil was then extracted with boiling water. Archaeological evidence shows that olives were turned into olive oil by 6000 BC and 4500 BC in present-day Israel and Palestine.
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 a number of purposes in this role:
Secondly, oils can be heated and used to cook other foods. Oils suitable for this objective must have a high flash point. Such oils include the major cooking oils – soybean, rapeseed, canola, sunflower, safflower, peanut, cottonseed, etc. Tropical oils, such as coconut, palm, and rice bran oils, are particularly valued in Asian cultures for high-temperature cooking, because of their unusually high flash points.
Unsaturated vegetable oils can be transformed through partial or complete "hydrogenation" into oils of higher melting point. The hydrogenation process involves "sparging" the oil at high temperature and pressure with hydrogen in the presence of a catalyst, typically a powdered nickel compound. As each carbon–carbon double-bond is chemically reduced to a single bond, two hydrogen atoms each form single bonds with the two carbon atoms. The elimination of double bonds by adding hydrogen atoms is called saturation; as the degree of saturation increases, the oil progresses toward being fully hydrogenated. An oil may be hydrogenated to increase resistance to rancidity (oxidation) or to change its physical characteristics. As the degree of saturation increases, the oil's viscosity and melting point increase.
The use of hydrogenated oils in foods has never been completely satisfactory. Because the center arm of the triglyceride is shielded somewhat by the end fatty acids, most of the hydrogenation occurs on the end fatty acids, thus making the resulting fat more brittle. A margarine made from naturally more saturated oils will be more plastic (more "spreadable") than a margarine made from hydrogenated soy oil. While full hydrogenation produces largely saturated fatty acids, partial hydrogenation results in the transformation of unsaturated cis fatty acids to unsaturated trans fatty acids in the oil mixture due to the heat used in hydrogenation. Partially hydrogenated oils and their trans fats have been linked to an increased risk of mortality from coronary heart disease, among other increased health risks.
In the US, the Standard of Identity for a product labeled as "vegetable oil margarine" specifies only canola, safflower, sunflower, corn, soybean, or peanut oil may be used. Products not labeled "vegetable oil margarine" do not have that restriction.
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. 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 hydroxyl group on the fatty acid. Castor oil is a precursor to Nylon 11.
Vegetable oil is used in 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.
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 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.
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:
The processing of vegetable oil in commercial applications is commonly done by chemical extraction, using solvent extracts, which produces higher yields and is quicker and less expensive. The most common solvent is petroleum-derived hexane. This technique is used for most of the "newer" industrial oils such as soybean and corn oils. After extraction, the solvent is evaporated out by heating the mixture to about 300 °F (149 °C).
Oils may be partially hydrogenated to produce various ingredient oils. Lightly hydrogenated oils have very similar physical characteristics to regular soy oil, but are more resistant to becoming rancid. Margarine oils need to be mostly solid at 32 °C (90 °F) so that the margarine does not melt in warm rooms, yet it needs to be completely liquid at 37 °C (98 °F), so that it doesn't leave a "lardy" taste in the mouth.
Hardening vegetable oil is done by raising a blend of vegetable oil and a catalyst in near-vacuum to very high temperatures, and introducing hydrogen. This causes the carbon atoms of the oil to break double-bonds with other carbons, each carbon forming a new single-bond with a hydrogen atom. Adding these hydrogen atoms to the oil makes it more solid, raises the smoke point, and makes the oil more stable.
Hydrogenated vegetable oils differ in two major ways from other oils which are equally saturated. During hydrogenation, it is easier for hydrogen to come into contact with the fatty acids on the end of the triglyceride, and less easy for them to come into contact with the center fatty acid. This makes the resulting fat more brittle than a tropical oil; soy margarines are less "spreadable". The other difference is that trans fatty acids (often called trans fat) are formed in the hydrogenation reactor, and may amount to as much as 40 percent by weight of a partially hydrogenated oil. Hydrogenated oils, especially partially hydrogenated oils with their higher amounts of trans fatty acids, are increasingly thought to be unhealthy.
In the processing of edible oils, the oil is heated under vacuum to near the smoke point or to about 450 °F (232 °C), and water is introduced at the bottom of the oil. The water immediately is converted to steam, which bubbles through the oil, carrying with it any chemicals which are water-soluble. The steam sparging removes impurities that can impart unwanted flavors and odors to the oil. Deodorization is key to the manufacture of vegetable oils. Nearly all soybean, corn, and canola oils found on supermarket shelves go through a deodorization stage that removes trace amounts of odors and flavors, and lightens the color of the oil.
People can breathe in vegetable oil mist in the workplace. The U.S. Occupational Safety and Health Administration (OSHA) has set the legal limit (permissible exposure limit) for vegetable oil mist exposure in the workplace as 15 mg/m3 total exposure and 5 mg/m3 respiratory exposure over an 8-hour workday. The U.S. National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 10 mg/m3 total exposure and 5 mg/m3 respiratory exposure over an 8-hour workday.
|Palm oil ||4.0|
|Coconut oil ||1.4|
|Canola oil ||1.4|
|Soybean oil ||0.6|
|Sunflower oil ||0.6|
The following triglyceride vegetable oils account for almost all worldwide production, by volume. All are used as both cooking oils and as SVO or to make biodiesel. According to the USDA, the total world consumption of major vegetable oils in 2007/08 was:
|Oil source||World consumption
(million metric tons)
|Palm||41.31||The most widely produced tropical oil, also used to make biofuel|
|Soybean||41.28||One of the most widely consumed cooking oils|
|Rapeseed||18.24||One of the most widely used cooking oils, canola is a variety (cultivar) of rapeseed|
|Sunflower seed||9.91||A common cooking oil, also used to make biodiesel|
|Peanut||4.82||Mild-flavored cooking oil|
|Cottonseed||4.99||A major food oil, often used in industrial food processing|
|Palm kernel||4.85||From the seed of the African palm tree|
|Coconut||3.48||Used in cooking, cosmetics and soaps|
|Olive||2.84||Used in cooking, cosmetics, soaps and as a fuel for traditional oil lamps|
Note that these figures include industrial and animal feed use. The majority of European rapeseed oil production is used to produce biodiesel, or used directly as fuel in diesel cars which may require modification to heat the oil to reduce its higher viscosity. The suitability of the fuel should come as little surprise, as Rudolf Diesel originally designed his engine to run on peanut oil.
Other significant triglyceride oils include:
|Monounsaturated fatty acids||Polyunsaturated fatty acids||Smoke point|
|Total mono||Oleic acid
|Total poly||linolenic acid
|Avocado||11.6||70.6||13.5||1||12.5||249 °C (480 °F)|
|Canola||7.4||63.3||61.8||28.1||9.1||18.6||238 °C (460 °F)|
|Coconut||82.5||6.3||6||1.7||175 °C (347 °F)|
232 °C (450 °F)
|Cottonseed||25.9||17.8||19||51.9||1||54||216 °C (420 °F)|
107 °C (225 °F)
|Grape seed||10.5||14.3||14.3||74.7||-||74.7||216 °C (421 °F)|
166 °C (330 °F)
|Olive||13.8||73.0||71.3||10.5||0.7||9.8||193 °C (380 °F)|
|Palm||49.3||37.0||40||9.3||0.2||9.1||235 °C (455 °F)|
|Peanut||20.3||48.1||46.5||31.5||31.4||232 °C (450 °F)|
|Safflower||7.5||75.2||75.2||12.8||0||12.8||212 °C (414 °F)|
|Soybean||15.6||22.8||22.6||57.7||7||51||238 °C (460 °F)|
|Sunflower (standard, 65% linoleic)||10.3||19.5||19.5||65.7||0||65.7|
|Sunflower (< 60% linoleic)||10.1||45.4||45.3||40.1||0.2||39.8||
227 °C (440 °F)
|Sunflower (> 70% oleic)||9.9||83.7||82.6||3.8||0.2||3.6||
227 °C (440 °F)
|Values as percent (%) by weight of total fat.|
Such oils have been part of human culture for millennia. Poppy seed, rapeseed, linseed, almond oil, sesame seed, safflower, and cotton seed were used since at least the bronze age throughout the Middle East and Central Asia. 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.
In modern times, cottonseed oil was marketed by Procter & Gamble as a creamed shortening in 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 can it 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 were an exciting new crop from China in the 1930s. Soy was protein-rich, and the medium viscosity oil 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, but 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.
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.
Recycled oil has numerous uses, including use as a direct fuel, as well as in the production of biodiesel, soap, animal feed, pet food, detergent, and cosmetics. It is traded as the commodity, yellow grease.
Since 2002, an increasing number of European Union countries have prohibited the inclusion of recycled vegetable oil from catering in animal feed. Used cooking oils from food manufacturing, however, as well as fresh or unused cooking oil, continue to be used in animal feed.
Due to their susceptibility to oxidation from the exposure to oxygen, heat and light, resulting in the formation of oxidation products, such as peroxides and hydroperoxides, plant oils rich in polyunsaturated fatty acids have a limited shelf-life.
In Canada, palm oil is one of five vegetable oils, along with palm kernel oil, coconut oil, peanut oil and cocoa butter, which must be specifically named in the list of ingredients for a food product. Also, oils in Canadian food products which have been modified or hydrogenated must contain the word "modified" or "hydrogenated" when listed as an ingredient. A mix of oils other than the aforementioned exceptions may simply be listed as "vegetable oil" in Canada; however, if the food product is a cooking oil, salad oil or table oil, the type of oil must be specified and listing "vegetable oil" as an ingredient is not acceptable.
From December 2014, all food products produced in the European Union were legally required to indicate the specific vegetable oil used in their manufacture, following the introduction of the Food Information to Consumers Regulation.
Certain crude oils that contain minor amounts of impurities other than free fatty acids can be refined by a process known as steam refining. It is merely a high-temperature steam distillation under reduced pressure. The crude vegetable oil is heated to about 450° F. and maintained under a pressure of 0.25 inch of mercury or less while steam is passed through it. The steam strips the free fatty acids out of the oil. The ]:>roccss is used somewhat in Europe but not often in the United States.
Brominated vegetable oil (BVO) is a complex mixture of plant-derived triglycerides that have been reacted to contain atoms of the element bromine bonded to the molecules. Brominated vegetable oil is used primarily to help emulsify citrus-flavored soft drinks, preventing them from separating during distribution. Brominated vegetable oil has been used by the soft drink industry since 1931, generally at a level of about 8 ppm.Careful control of the type of oil used allows bromination of it to produce BVO with a specific density of 1.33 g/mL, which is noticeably greater than that of water (1 g/mL). As a result, it can be mixed with less-dense flavoring agents such as citrus flavor oil to produce a resulting oil whose density matches that of water or other products. The droplets containing BVO remain suspended in the water rather than separating and floating at the surface.Alternative food additives used for the same purpose include sucrose acetate isobutyrate (SAIB, E444) and glycerol ester of wood rosin (ester gum, E445).Bromoderma
Bromoderma is a skin condition characterized by an eruption of papules and pustules on the skin. It is caused by hypersensitivity to bromides, such as those found in certain drugs. There is at least one reported case of bromoderma caused by excessive consumption of a soft drink containing brominated vegetable oil.Cheez-It
Cheez-It is a cheese cracker manufactured by the Kellogg Company through its Sunshine Biscuits division. Approximately 26 by 26 millimetres (1.0 by 1.0 in), the square crackers are made with wheat flour, vegetable oil, cheese made with skim milk, salt, and spices.
Cheez-It crackers were introduced in 1921 by the Green & Green Company, a manufacturer of snack crackers based in Dayton, Ohio, and were marketed using the tagline "A Baked Rarebit." Sunshine Biscuits acquired Green & Green in 1932. Sunshine Biscuits became a subsidiary of the Keebler Company in 1996. Keebler, in turn, was acquired by Kellogg in 2001.Chiffon cake
A chiffon cake is a very light cake made with vegetable oil, eggs, sugar, flour, baking powder, and flavorings.
Its distinctive feature is from the use of vegetable oil, instead of the traditional fat which is solid at room temperature, such as butter or shortening. This makes it difficult to directly beat air into the batter. As a result, chiffon cakes (angel cakes and other foam cakes) achieve a fluffy texture by having egg whites beaten separately until stiff and then folded into the cake batter before baking. Its aeration properties rely on both the quality of the meringue and the chemical leaveners.
A chiffon cake combines methods used with sponge cakes and conventional cakes. It includes baking powder and vegetable oil, but the eggs are separated and the whites are beaten before being folded into the batter, creating the rich flavor like an oil cake, but with a lighter texture that is more like a sponge cake. They can be baked in tube pans or layered with fillings and frostings. In the original recipe, the cake tin is not lined or greased, which enables the cake batter to stick to side of the pan, giving the cake better leverage to rise, as well as support in the cooling process when the cake is turned upside down to keep air bubbles stable.Chili oil
Chili oil is a condiment made from vegetable oil that has been infused with chili peppers. It is commonly used in Chinese cuisine, East and Southeast Asia and elsewhere. Particularly popular in Sichuan cuisine, it is used as an ingredient in cooked dishes as well as a condiment. It is sometimes used as a dip for meat and dim sum. It is also employed in the Korean Chinese noodle soup dish jjamppong.
Chili oil is typically red in color. It is made from vegetable oil, often soybean oil or sesame oil, although olive oil or other oils may be used. Other spices may be included such as Sichuan pepper, garlic, or paprika. Commercial preparations may include other kinds of oil, water, dried garlic, soy sauce, and sugar. Recipes targeted to Western cooks also suggest other popular oils such as rapeseed, grapeseed or peanut, and any dried or fresh chili peppers. The solids typically settle to the bottom of the container in which it is stored. When using chili oil, the cook or diner may choose how much of the solids to use; sometimes only the oil is used, without any solids.
Chili oil is commercially available in glass jars, although it may also be made from scratch at home. It is usually available by request at Chinese restaurants.Hydrogenation
Hydrogenation – meaning, to treat with hydrogen – is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons.Khrongkhraeng krop
Khrongkhraeng krop (Thai: ครองแครงกรอบ, pronounced [kʰrɔ̄ːŋ.kʰrɛ̄ːŋ krɔ̀ːp]) is traditional Thai dessert that is a dry, crisp favourite. It is made from dough and fried. The main ingredients are wheat flour, eggs, coconut milk, salt, sugar, vegetable oil, garlic, chili, parsley root and pepper. The taste of khrongkhraeng krop is a little spicy from peppers with the scent of garlic with cilantro root.Ngome (bread)
Ngome is a flatbread made in Mali using only millet, water and vegetable oil. The millet is typically home-ground and coarse.PSA XUD
See also PSA XU engine for the related gasoline variantThe PSA XUD is a Diesel engine designed and built by PSA - Peugeot and Citroën. It is an Indirect injection (IDI) engine, that uses a version of the Ricardo Consulting Engineers Ricardo Comet V prechamber cylinder head design. The engine comes in 1.8 L (1,769 cc) N/A, 1.8 Turbo, 1.9 L (1,905 cc) N/A, Turbo, 2.1 12 valve N/A and Turbo and was the predecessor to the HDI range of engines. Early HDi Engines were a PSA design, later 16 valve engines were jointly developed with Ford.Pindjur
Pindjur or pinjur or pinđur (Bosnian: pinđur, Bulgarian: пинджур, Serbian: пинђур, pinđur, Macedonian: пинџур) is a relish form and is commonly used as a summer spread. Pindjur is commonly prepared in Bosnia and Herzegovina, Bulgaria, Serbia and Macedonia.
The traditional ingredients include red bell peppers, tomatoes, garlic, vegetable oil, and salt. Pindjur is similar to ajvar but is generally made with tomatoes. In some regions the words are used interchangeably.
The creation of this traditional relish is a rather long process which involves baking some of the ingredients for hours, as well as roasting the peppers and peeling them.Qottab
Qottab (Persian: قطاب qottâb) is an almond-filled deep-fried Iranian cuisine pastry or cake, prepared with flour, almonds, powdered sugar, vegetable oil, and cardamom. The city of Yazd is well known for its qottab.Rapeseed
Rapeseed (Brassica napus), also known as rape, oilseed rape, and, in the case of one particular group of cultivars, canola, is a bright-yellow flowering member of the family Brassicaceae (mustard or cabbage family), cultivated mainly for its oil-rich seed. It is the third-largest source of vegetable oil and second-largest source of protein meal in the world.Shelpek
Shelpek (Turkmen: çelpek; Kazakh: шелпек/shelpek; Kyrgyz: май токоч, челпек; Uzbek: chalpak/чалпак; Uyghur: , ULY: chalpyak) is a traditional Central Asian flatbread commonly consumed all over the region. The main ingredients of shelpek are flour, milk, sugar, butter, sour cream such as Kaymak, baking soda, salt and vegetable oil.
The dough is shaped into balls and fried in hot vegetable oil until reaching a golden color. Shelpek can also be prepared with yeast, thus the dough stays soft for a longer period of time. The recipe to prepare the dough in the given case is similar to the one used for baursak.Toum
Toum or Toumya (Levantine Arabic: ْتُوم "garlic") is a garlic sauce common to the Levant. Similar to the Provençal aioli, it contains garlic, salt, olive oil or vegetable oil, and lemon juice, traditionally crushed together using a wooden mortar and pestle. There is also a variation popular in many places, such as the town of Zgharta, in Lebanon, where mint is added; it is called "zeit wa toum" (oil and garlic).Toum is used as a dip, especially with French fries and chicken, and in Levantine sandwiches, especially those containing chicken.Vegetable oil fuel
Vegetable oil can be used as an alternative fuel in diesel engines and in heating oil burners. When vegetable oil is used directly as a fuel, in either modified or unmodified equipment, it is referred to as straight vegetable oil (SVO) or pure plant oil (PPO). Conventional diesel engines can be modified to help ensure that the viscosity of the vegetable oil is low enough to allow proper atomization of the fuel. This prevents incomplete combustion, which would damage the engine by causing a build-up of carbon. Straight vegetable oil can also be blended with conventional diesel or processed into biodiesel or bioliquids for use under a wider range of conditions.Vegetable oil recycling
Vegetable oil recycling is increasingly being carried out to produce a vegetable oil fuel.
In the UK, waste cooking oil collection is governed by the environment agency. All waste cooking oil collections need to be carried out by a company registered as a waste carrier by the environment agency. On each collection a waste transfer note needs to the filled out and copies held by both parties for a minimum of 3 years. Waste transfer notes need to contain:
Full company details of who the waste is being transferred to:
Their waste registration details
Full details of who the waste is being transferred from
Signatures from both partiesWaste transfer notes can be hard paper copies or electronic versions. Here is an example of a waste transfer note currently is use by a UK waste cooking oil company.
Opportunities for businesses and consumers to recycle used cooking oil ("yellow grease") has increased. Used cooking oil can be refined into different types of biofuels used for power generation and heating. A significant benefit is that biofuels derived from recycled cooking oil typically burn clean, have a low carbon content and do not produce carbon monoxide. This helps communities to reduce their carbon footprints. The recycling of cooking oil also provides a form of revenue for restaurants, which are sometimes compensated by cooking oil recyclers for their used deep fryer oil. Cooking oil recycling also results in less used oil being disposed of in drains, which can clog sewage lines due to the build-up of fats and has to be collected there as "brown grease" by grease traps.Vegetable oil refining is a process to transform vegetable oil into fuel by hydrocracking or hydrogenation. Hydrocracking breaks larger molecules into smaller ones using hydrogen while hydrogenation adds hydrogen to molecules. These methods can be used for production of gasoline, diesel, and propane. The diesel fuel that is produced has various names including green diesel or renewable diesel.
In the past waste oils were collected by pig farmers as part of food waste from pig swill bins. The grease was skimmed off the swill tanks and sold for further processing, while the remaining swill was processed into pig food.Vegetable oil refining
Vegetable oil refining is a process to transform vegetable oil into biofuel by hydrocracking or hydrogenation. Hydrocracking breaks big molecules into smaller ones using hydrogen while hydrogenation adds hydrogen to molecules. These methods can be used for production of gasoline, diesel, propane, and other chemical feedstock. Diesel fuel produced from these sources is known as green diesel or renewable diesel.Vegetable oils as alternative energy
Vegetable oils are increasingly used as a substitute for fossil fuels. Vegetable oils are the basis of biodiesel, which can be used like conventional diesel. Some vegetable oil blends are used in unmodified vehicles, but straight vegetable oil needs specially prepared vehicles which have a method of heating the oil to reduce its viscosity and surface tension. Another alternative is vegetable oil refining.
The availability of biodiesel around the world is increasing, although still tiny compared to conventional fossil fuel sources. There is significant research in algaculture methods to make biofuel from algae.
Concerns have been expressed about growing crops for fuel use rather than food and the environmental impacts of large-scale agriculture and land clearing required to expand the production of vegetable oil for fuel use. These effects/impacts would need to be specifically researched and evaluated, economically and ecologically, and weighed in balance with the proposed benefits of vegetable oil fuel in relation to the use of other fuel sources.Yellow grease
Yellow grease, also termed used cooking oil (UCO), used vegetable oil (UVO), recycled vegetable oil, or waste vegetable oil (WVO) is recovered from businesses and industry that use the oil for cooking.
It is used to feed livestock, and to manufacture soap, make-up, clothes, rubber, and detergents. Due to competition from these other industrial sectors, the EIA estimates that less than a third of yellow grease could be spared for biodiesel production annually.It is distinct from brown grease; yellow grease is typically used frying oils from deep fryers, whereas brown grease is sourced from grease interceptors.