lecithin

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(lĕs'ə-thĭn) pronunciation
n.
Any of a group of phospholipids found in egg yolks and the plasma membrane of plant and animal cells, used as an emulsifier in a wide range of commercial products, including foods, cosmetics, paints, and plastics. Also called phosphatidylcholine.

[French lécithine : Greek lekithos, egg yolk + French -ine, -in.]



Any of a class of phospholipids (also called phosphatidyl cholines) important in cell structure and metabolism. They are composed of phosphate, choline, glycerol (as the ester), and two fatty acids. Various fatty acids pairs distinguish the various lecithins. Commercial lecithin, a wetting and emulsifying agent used in animal feeds, baking products and mixes, chocolate, cosmetics and soap, insecticides, paint, and plastics, is a mixture of lecithins and other phospholipids in an edible oil.

For more information on lecithin, visit Britannica.com.

Chemically lecithin is phosphatidyl choline; a phospholipid containing choline. Commercial lecithin, prepared from soya bean, peanut, and maize, is a mixture of phospholipids in which phosphatidyl choline predominates. Used in food processing as an emulsifier, e.g. in salad dressing, processed cheese, and chocolate, and as an anti-spattering agent in frying oils. Is plentiful in the diet and not a dietary essential.

A compound consisting of two fatty acid chains, a phosphate group, and a base (choline), present in egg yolk and soya beans. It is also called phosphatidyl-choline. Lecithin usually contains a high proportion of linoleic acid. It is often added to processed foods as an emulsifying agent, binding food components together and making them more soluble. In the body, lecithin is a component of cell membranes, including the myelin sheath around nerves, and it is involved in fat metabolism. It has been claimed that lecithin helps cholesterol bind to the high density lipoproteins that remove the cholesterol from tissues. The involvement of lecithin in fat mobilization has led to it being sold as a slimming aid, but there is no evidence that it helps weight reduction. On the contrary it is probably just as fattening as other vegetable oils. Some coaches prescribe lecithin in post-competition diets because they believe it accelerates recovery.

[LEHS-uh-thihn] A fatty substance obtained from egg yolks and legumes, used to preserve, emulsify and moisturize food. Lecithin-vegetable oil sprays (available in every supermarket) can be used instead of high-calorie oils for greasing pans and sautéing foods.

A liquid, obtained in refinement of soya beans or cottonseed; used in paints to promote pigment wetting and to control pigment settling and flow properties.


A phospholipid present in large amounts in egg yolk and soya beans. It is involved in fat metabolism and is a component of cell membranes and the myelin sheath of nerves. It has been claimed that inclusion of lecithin in a post-competition diet accelerates recovery.


A phospholipid, which, by virtue of the fact that it has both polar and non-polar structures on the molecule, may act as an emulsifying agent. Lecithin can be derived from soybeans and is also present in egg yolks. Lecithin is needed by cells and is a key component of membranes. In the membrane, it functions as an anti-hardening substance. Furthermore, lecithin protects cells from oxidation as well as protecting the brain by forming sheaths that surround it. Chemically, the molecule of lecithin contains phosphoric acid esterified with a molecule of choline. In foods, lecithin is found in both soybeans and egg yolks. As it is used typically in a food product, one problem that might arise is a soapy, sometimes bitter flavor. Refined versions tend to overcome this off note. Recent claims for the use and consumption of lecithin as a dietary supplement claims its emulsification ability and the theory that blood content of lecithin could dissolve cholesterol deposits. This has so far not been conclusively supported. See Emulsifying Agent, Emulsion, Micelle.

Any of a group of phospholipids found in animal tissues, especially nerve tissue, the liver, semen and egg yolk, consisting of esters of glycerol with two molecules of long-chain aliphatic acids and one of phosphoric acid, the latter being esterified with the alcohol group of choline.

(les'ithin)
n

A class of phosphatides containing glycerol, phosphate, choline, and fatty acids. Lecithins are widely distributed in cells and possess both metabolic and structural functions in membranes. Dipalmityl lecithin is an important surface-active agent in the lungs.

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An example of a phosphatidylcholine, a type of phospholipid in lecithin. Red - choline and phosphate group; Black - glycerol; Green - unsaturated fatty acid; Blue - saturated fatty acid

Lecithin is a generic term to designate any group of yellow-brownish fatty substances occurring in animal and plant tissues composed of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides, and phospholipids (e.g., phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol).

Lecithin was first isolated in 1846 by the French chemist and pharmacist Theodore Gobley;[1] in 1850 he named the phosphatidylcholine léchithine.[2] Gobley originally isolated lecithin from egg yolk—λέκιθος (lekithos) is 'egg yolk' in ancient Greek—and established the complete chemical formula of phosphatidylcholine in 1874;[3] in between, he had demonstrated the presence of lecithin in a variety of biological matters, including venous blood, bile, human brain tissue, fish eggs, fish roe, chicken and sheep brain.

Lecithin can easily be extracted chemically (using hexane) or mechanically from readily available sources such as soy beans. It has low solubility in water. In aqueous solution, its phospholipids can form either liposomes, bilayer sheets, micelles, or lamellar structures, depending on hydration and temperature. This results in a type of surfactant that is usually classified as amphipathic. Lecithin is sold as a food supplement and for medical uses. In cooking, it is sometimes used as an emulsifier and to prevent sticking, for example in nonstick cooking spray.

Contents

Biology

Phosphatidylcholine occurs in all cellular organisms, being one of the major components of the phospholipid portion of the cell membrane.

Production

Commercial lecithin, as used by food manufacturers, is a mixture of phospholipids in oil. The lecithin can be obtained by degumming the extracted oil of seeds. It is a mixture of various phospholipids, and the composition depends on the origin of the lecithin. A major source of lecithin is soybean oil. Because of the EU requirement to declare additions of allergens in foods, in addition to regulations regarding genetically modified crops, a gradual shift to other sources of lecithin (e.g., sunflower oil) is taking place. The main phospholipids in lecithin from soya and sunflower are phosphatidyl choline, phosphatidyl inositol, phosphatidyl ethanolamine, and phosphatidic acid. They are often abbreviated to PC, PI, PE, and PA, respectively.

Hydrolysed lecithin

To modify the performance of lecithin to make it suitable for the product to which it is added, it may be hydrolysed enzymatically. In hydrolysed lecithins, a portion of the phospholipids have one fatty acid removed by phospholipase. Such phospholipids are called lysophospholipids. The most commonly used phospholipase is phospholipase A2, which removes the fatty acid at the C2 position of glycerol. Lecithins may also be modified by a process called fractionation. During this process, lecithin is mixed with an alcohol, usually ethanol. Some phospholipids, such as phosphatidylcholine, have good solubility in ethanol, whereas most other phospholipids do not dissolve well in ethanol. The ethanol is separated from the lecithin sludge, after which the ethanol is removed by evaporation to obtain a phosphatidylcholine-enriched lecithin fraction.

Properties and applications

Lecithin has emulsification and lubricant properties, and is a surfactant. It can be totally metabolized (see Inositol) by humans, so is well tolerated by humans and nontoxic when ingested; some emulsifiers can only be excreted via the kidneys.

Lecithin is used for applications in human food, animal feed, pharmaceutical, paint, and other industrial applications.

Applications listed by one manufacturer, in addition to food applications, include:[4]

  • In the pharmaceutical industry, it acts as a wetting, stabilizing agent and a choline enrichment carrier, helps in emulsifications and encapsulation, and is a good dispersing agent. It can be used in manufacture of intravenous fat infusions and for therapeutic use.
  • In animal feed, it enriches fat and protein and improves pelletization.
  • In the paint industry, it forms protective coatings for surfaces with painting and printing ink, has antioxidant properties, helps as a rust inhibitor, is a colour-intensifying agent, catalyst, conditioning aid modifier, and dispersing aid; it is a good stabilizing and suspending agent, emulsifier, and wetting agent, helps in maintaining uniform mixture of several pigments, helps in grinding of metal oxide pigments, is a spreading and mixing aid, prevents hard settling of pigments, eliminates foam in water-based paints, and helps in fast dispersion of latex-based paints.
  • Lecithin can also be used as a release agent for plastics, an antisludge additive in motor lubricants, an antigumming agent in gasoline, and an emulsifier, spreading agent, and antioxidant in textile, rubber and other industries.

Use with food, and health effects

The nontoxicity of lecithin leads to its use with food, as an additive or in food preparation. It is used commercially in foods requiring a natural emulsifier or lubricant. In the food industry, it has multiple uses: In confectionery, it reduces viscosity, replaces more expensive ingredients, controls sugar crystallization and the flow properties of chocolate, helps in the homogeneous mixing of ingredients, improves shelf life for some products, and can be used as a coating. In emulsions and fat spreads, it stabilizes emulsions, reduces spattering during frying, improves texture of spreads and flavour release. In doughs and bakery, it reduces fat and egg requirements, helps even distribution of ingredients in dough, stabilizes fermentation, increases volume, protects yeast cells in dough when frozen, and acts as a releasing agent to prevent sticking and simplify cleaning. It improves wetting properties of hydrophilic powders (e.g., low-fat proteins) and lipophilic powders (e.g., cocoa powder), controls dust, and helps complete dispersion in water.[4] It can be used as a component of cooking sprays to prevent sticking and as a releasing agent.

For example, lecithin is the emulsifier that keeps cocoa and cocoa butter in a candy bar from separating. In margarines, especially those containing high levels of fat (>75%), lecithin is added as an 'antispattering' agent for shallow frying.

It is approved by the United States Food and Drug Administration for human consumption with the status "generally recognized as safe." Lecithin is admitted by the EU as a food additive, designated by E number E322. Research studies show soy-derived lecithin has significant effects on lowering serum cholesterol and triglycerides, while increasing HDL ("good cholesterol") levels in the blood.[5][6] However, studies on egg lecithin have been inconsistent and contradictory since the 1920s.[7]

New studies suggest gut bacteria metabolites of choline promote atherosclerosis in mice through TMAO production and "augmented macrophage cholesterol accumulation and foam cell formation".[8] Mice fed with egg-yolk derived lecithin developed arterial plaque in spite of no increase in cholesterol or triglyceride levels.[9]

Compatibility with special diets

A proven benefit and suggested use for lecithin is for those taking niacin to treat high cholesterol. Niacin treatment can deplete choline, necessitating an increased amount of lecithin or choline in the diet.[10][11][12][13][14] Egg-derived lecithin may be a concern for those following some specialized diets. Egg lecithin is not a concern for those on low-cholesterol diets, because the lecithin found in eggs markedly inhibits the absorption of the cholesterol contained in eggs.[15] There is no general agreement among vegetarians concerning egg-derived lecithin; vegans and lactovegetarians would likely abstain from it.

Religious restrictions

Soy-derived lecithin is considered by some to be kitniyot and prohibited on Passover for Ashkenazi Jews when many grain-based foods are forbidden, but not at other times. This does not necessarily affect Sephardi Jews, who do not have the same restrictions on rice and kitniyot during Pesach/Passover.[16]

Muslims are not forbidden to eat lecithin per se; however, since it may be derived from animal as well as plant sources, care must be taken to ensure this source is halal. Lecithin derived from plants and egg yolks is permissible, as is that derived from animals slaughtered according to the rules of dhabihah.[17]

References

  1. ^ Gobley (1846) "Recherches chimiques sur le jaune d'œuf" (Chemical researches on egg yolk), Journal de Pharmacie et de Chemie, series 3, vol. 9, pages 81-91; on page 84, Gobley gives the proceedure by which he extracted and characterized lecithin.
  2. ^ Gobley (1850) Recherches chemiques sur les œufs de carpe (Chemical researches on carp eggs), Journal de Pharmacie et de Chemie, series 3, vol. 17, pages 401-430; see especially page 411: "Je propose de donner au premier le nom de Léchithine (de λεχιθος, jaune d'œuf), parce qu'on le rencontre en grande quantité dans le jaune d'œuf,..." (I propose to give the first [substance] the name "Lecithin" (from λεχιθος, egg yolk), because one finds it in large quantities in egg yolk,....)
  3. ^ Theodore Gobley "Sur la lécithine et la cérébrine"; Journal de Pharmacie et de Chimie 1874,t20, 98-103, 161-166". 
  4. ^ a b Supplier's website with lecithin applications
  5. ^ Iwata T, Kimura Y, Tsutsumi K, Furukawa Y, Kimura S (February 1993). "The effect of various phospholipids on plasma lipoproteins and liver lipids in hypercholesterolemic rats". J. Nutr. Sci. Vitaminol. 39 (1): 63–71. doi:10.3177/jnsv.39.63. PMID 8509902. 
  6. ^ Jimenez MA, Scarino ML, Vignolini F, Mengheri E (July 1990). "Evidence that polyunsaturated lecithin induces a reduction in plasma cholesterol level and favorable changes in lipoprotein composition in hypercholesterolemic rats". J. Nutr. 120 (7): 659–67. PMID 2366101. http://jn.nutrition.org/cgi/pmidlookup?view=long&pmid=2366101. 
  7. ^ Kaayla T. Daniel, PhD, CCN (Winter 2003). "Soy Lecithin: From Sludge to Profit". Wise Traditions in Food, Farming, and the Healing Arts 4 (4). http://www.westonaprice.org/soy-alert/694-soy-lecithin-from-sludge-to-profit.html. 
  8. ^ Hazen, Stanley L.; et al (7 April 2011). "Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease". Nature 472 (7341): 57–63. doi:10.1038/nature09922. PMC 3086762. PMID 21475195. http://www.nature.com/nature/journal/v472/n7341/full/nature09922.html. Retrieved 9 April 2011. 
  9. ^ Zeneng Wang et al., (2011 April 7) "Gut flora metabolism of phosphatidylcholine promotes cardiovascular disease", Nature, Vol. 472(7341): 57–63 [1]
  10. ^ J Nutr. 1965 Jan;85:107-12., FATTY LIVERS PRODUCED IN ALBINO RATS BY EXCESS NIACIN IN HIGH FAT DIETS. II. EFFECT OF CHOLINE SUPPLEMENTS.
  11. ^ British Journal of Nutrition (1996), 75:471-481 Cambridge University Press, Cholesterol-lowering effect of soyabean lecithin in normolipidaemic rats by stimulation of biliary lipid secretion
  12. ^ Iowa State University Animal Industry Report 2006, Soy Lecithin but Not Egg Lecithin Decreased the Plasma Cholesterol Concentration in Golden Syrian Hamsters
  13. ^ Life Sciences, Volume 67, Issue 21, 13 October 2000, Pages 2563-2576, Dietary polyenylphosphatidylcholine decreases cholesterolemia in hypercholesterolemic rabbits: Role of the hepato-biliary axis.
  14. ^ J Pharm Pharmacol. 2005 Jul;57(7):889-96, Phytostanol tablets reduce human LDL-cholesterol.
  15. ^ Unisci.com, Why Eggs Don't Contribute Much Cholesterol To Diet.
  16. ^ (Reb Yehonatan Levy, Shomer Kashrut Mashgiach - based upon halachic rulings of CRC - Chicago Rabbinic Council, and from shiurim/lessons by Rabbi D. Raccah on "Pesach Preparations" following commentary from former Rishon-LeTzion Rav Ovadia Yosef). OK Kosher Certification, Keeping Kosher for Pesach. Retrieved on Sept 10, 2008.
  17. ^ Islamic Food and Nutrition Council of America FAQ, IFANCA: Consumer FAQ. Retrieved on July 7, 2010. The practice of consuming Halal products is not widespread among Muslims, the practice is common with Muslims who follow Sharia laws.

External links


Translations:

Lecithin

Top

Dansk (Danish)
n. - lecithin

Nederlands (Dutch)
lecithine

Français (French)
n. - lécithine

Deutsch (German)
n. - (Chem.) Lezithin

Ελληνική (Greek)
n. - (χημ.) λεκιθίνη

Italiano (Italian)
lecitina

Português (Portuguese)
n. - lecitina (f) (Quím.)

Русский (Russian)
лецитин

Español (Spanish)
n. - lecitina

Svenska (Swedish)
n. - (kem.) lecitin

中文(简体)(Chinese (Simplified))
蛋黄素, 卵磷脂

中文(繁體)(Chinese (Traditional))
n. - 蛋黃素, 卵磷脂

한국어 (Korean)
n. - 동물성 지방 모양의 황색 물질

日本語 (Japanese)
n. - レシチン, レシチン含有物

العربيه (Arabic)
‏(الاسم) اللستين, مادة دهنيه في صفات البيض وأنسجه الحيوان والنبات‏

עברית (Hebrew)
n. - ‮לציטין (לפתית), שומן המכיל זרחן‬


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