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Fat hydrogenation is the process of combining
fat In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food. The term often refers specifically to triglycerides (triple est ...
– typically liquid vegetable oils – with hydrogen, to convert some or all of the
unsaturated fat An unsaturated fat is a fat or fatty acid in which there is at least one double bond within the fatty acid chain. A fatty acid chain is monounsaturated if it contains one double bond, and polyunsaturated if it contains more than one double bond ...
into saturated fat, resulting in a solid or semi-solid fat. Changing the degree of saturation of the fat changes some important physical properties, such as the melting range, which is why liquid oils become semi-solid. Solid or semi-solid fats are preferred for baking because the way the fat mixes with flour produces a more desirable texture in the baked product. Because partially hydrogenated vegetable oils are cheaper than animal fats, are available in a wide range of consistencies, and have other desirable characteristics such as increased oxidative
stability Stability may refer to: Mathematics * Stability theory, the study of the stability of solutions to differential equations and dynamical systems **Asymptotic stability **Linear stability **Lyapunov stability **Orbital stability **Structural stabili ...
and longer shelf life, they are the predominant fats used as shortening in most commercial baked goods. The process is typically carried out at very high pressure, with the help of a nickel catalyst that is removed from the final product.


Process

Hydrogenating vegetable oil is done by raising a blend of vegetable oil and a metal catalyst, typically nickel, 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 atom becomes single-bonded to an individual hydrogen atom, and the double bond between carbons can no longer exist. Full hydrogenation results in the conversion of all of the unsaturated fats into saturated fats by transforming all of the double bonds in the fat into single bonds. Partial hydrogenation reduces some, but not all, of the double bonds by the partial replacement with single bonds. The degree of hydrogenation is controlled by restricting the amount of hydrogen, reaction temperature and time, and the catalyst.


Issues

''Cis''–''trans'' isomerization of some of the remaining unsaturated carbon bonds to their trans isomers during the hydrogenation process produces trans fat, which have been demonstrated to have cardiovascular health risk. The conversion from cis to trans bonds is chemically favored because the trans configuration has lower energy than the natural cis one. At equilibrium, the trans/cis isomer ratio is about 2:1. Numerous studies have concluded that these ''trans'' fatty acids have negative health effects. As a result, many countries have enacted trans fat regulation that aims to eliminate or severely restrict their amount in industrialized food products, such as mandatory labeling of trans fats on food products. The
United States Food and Drug Administration The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food s ...
has concluded that partially hydrogenated oils are not generally recognized as safe, and since 2018 categorizes them as food additives, not food.


Dietary recommendations

Recommendations to reduce, limit or replace dietary intake of
trans fats Trans fat, also called trans-unsaturated fatty acids, or trans fatty acids, is a type of unsaturated fat that naturally occurs in small amounts in meat and milk fat. It became widely produced as an unintentional byproduct in the industrial pro ...
and saturated fats, in favor of unsaturated fats, are made by the World Health Organization, American Heart Association, Health Canada, the US Department of Health and Human Services, the UK National Health Service, the UK Scientific Advisory Committee on Nutrition,"Saturated Fats and Health"
Scientific Advisory Committee on Nutrition (SACN). Retrieved 26 July 2021.
the Australian Department of Health and Aging, the Singapore Ministry of Health, the Indian Ministry of Health and Family Welfare, the New Zealand Ministry of Health, and Hong Kong's Department of Health.


History

Nobel
laureate In English, the word laureate has come to signify eminence or association with literary awards or military glory. It is also used for recipients of the Nobel Prize, the Gandhi Peace Award, the Student Peace Prize, and for former music directo ...
Paul Sabatier worked in the late 1890s to develop the chemistry of hydrogenation. Whereas Sabatier considered hydrogenation of only vapors, the German
chemist A chemist (from Greek ''chēm(ía)'' alchemy; replacing ''chymist'' from Medieval Latin ''alchemist'') is a scientist trained in the study of chemistry. Chemists study the composition of matter and its properties. Chemists carefully describe th ...
Wilhelm Normann Wilhelm Normann (16 January 1870, in Petershagen – 1 May 1939, in Chemnitz) (sometimes also spelled ''Norman'') was a German chemist who introduced the hydrogenation of fats in 1901, creating what later became known as trans fats. This inventi ...
showed in 1901 that liquid oils could be hydrogenated, and patented the process in 1902. Normann's hydrogenation process made it possible to stabilize affordable whale oil or
fish oil Fish oil is oil derived from the tissues of oily fish. Fish oils contain the omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), precursors of certain eicosanoids that are known to reduce inflammation in the body ...
for human consumption, a practice kept secret to avoid consumer distaste. During the years 1905–1910, Normann built a fat-hardening facility in the Herford company. At the same time, the invention was extended to a large-scale plant in
Warrington Warrington () is a town and unparished area in the borough of the same name in the ceremonial county of Cheshire, England, on the banks of the River Mersey. It is east of Liverpool, and west of Manchester. The population in 2019 was esti ...
, England, at Joseph Crosfield & Sons, Limited. It took only two years until the hardened fat could be successfully produced in the plant in Warrington, commencing production in late 1909. The initial year's production totalled nearly 3,000 tonnes. In 1909, Procter & Gamble acquired the United States rights to the Normann patent. In 1911, they began marketing the first hydrogenated shortening,
Crisco Crisco is an American brand of shortening that is produced by B%26G Foods. Introduced in June 1911 by Procter & Gamble, it was the first shortening to be made entirely of vegetable oil, originally cottonseed oil. Additional products marketed u ...
, composed largely of partially hydrogenated
cottonseed oil Cottonseed oil is cooking oil from the seeds of cotton plants of various species, mainly ''Gossypium hirsutum'' and ''Gossypium herbaceum'', that are grown for cotton fiber, animal feed, and oil. Cotton seed has a similar structure to other oil ...
. Further success came from the marketing technique of giving away free cookbooks in which every recipe called for Crisco. In the early 20th century, soybeans began to be imported into the United States as a source of protein; large quantities of soybean oil were a by-product. At the same time, there was not enough butterfat available for consumers.
Margarine Margarine (, also , ) is a spread used for flavoring, baking, and cooking. It is most often used as a substitute for butter. Although originally made from animal fats, most margarine consumed today is made from vegetable oil. The spread was or ...
manufacturers found that hydrogenated fats worked better than the previously used combination of animal and liquid vegetable fats. Margarine made from hydrogenated soybean oil and vegetable shortenings such as Crisco and Spry, sold in England, began to replace butter and lard in baking bread, pies, cookies, and cakes by 1920. Production of hydrogenated fats increased steadily until the 1960s, as processed vegetable fats replaced animal fats in the United States and other Western countries. At first, the argument was a financial one due to lower costs; advocates also said that the hydrogenated fats of margarine were healthier than the saturated fats of butter. The food industry has moved away from partially hydrogenated fats in response to the health concerns about trans fats, labeling requirements, and removal of trans fats from permitted food additives. They have been replaced with fully hydrogenated fats, vegetable oils that are naturally higher in saturated fat and therefore more solid at room temperature, such as palm oil and
coconut oil frameless , right , alt = A cracked coconut and a bottle of coconut oil Coconut oil (or coconut butter) is an edible oil derived from the wick, meat, and milk of the coconut palm fruit. Coconut oil is a white solid fat; in warmer climates du ...
, and
interesterified fat In the food industry and biochemistry, interesterification (IE) is a process that rearranges the fatty acids of a fat product, typically a mixture of triglyceride. The process implies breaking and reforming the ester bonds C–O–C that conne ...
s, which cannot result in the formation of trans fats.


See also

* Hydrotreated vegetable oil


References

Reprinted online: NOTE: Unreliable source.


External links

* {{Vascular diseases