Lecithin ( ; ) is a generic term to designate any group of yellow-brownish lipid substances occurring in animal and plant tissues which are amphiphilic – they attract both water and fatty substances (and so are both hydrophilic and lipophilic), and are used for smoothing food textures, Emulsion, homogenizing liquid mixtures, and repelling sticking materials.
Lecithins are mixtures of glycerophospholipids including phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, and phosphatidic acid.
Lecithin was first isolated in 1845 by the French chemist and pharmacist Théodore Gobley.
Lecithin can easily be extracted chemically using solvents such as hexane, ethanol, acetone, petroleum ether or benzene; or extraction can be done mechanically. Common sources include egg yolk,
Production
Commercial lecithin, as used by food manufacturers, is a mixture of
in oil. The lecithin can be obtained by water 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
European Union requirement to declare additions of allergens in foods, in addition to regulations regarding genetically modified crops, a gradual shift to other sources of lecithin (such as sunflower lecithin) is taking place.
The main phospholipids in lecithin from soy and sunflower are phosphatidylcholine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylserine, and phosphatidic acid. They are often abbreviated to PC, PI, PE, PS and PA, respectively. Purified phospholipids are produced by companies commercially.
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.
Genetically modified crops as a source of lecithin
As described above, lecithin is highly processed. Therefore, genetically modified (GM)
protein or
DNA from the original GM crop from which it is derived often is undetectable – in other words, it is not substantially different from lecithin derived from non-GM crops.
Nonetheless, consumer concerns about genetically modified food have extended to highly purified derivatives from GM food, such as lecithin.
This concern led to policy and regulatory changes in the
European Union in 2000, when Commission Regulation (EC) 50/2000 was passed
which required labelling of food containing additives derived from GMOs, including lecithin. Because it is nearly impossible to detect the origin of derivatives such as lecithin, the European regulations require those who wish to sell lecithin in
Europe to use a meticulous, but essential system of identity preservation (IP).
Properties and applications
Lecithins have
emulsion and
lubricant properties, and are a
surfactant. They can be completely
metabolism (see
inositol) by humans, so are well tolerated by humans and
nontoxic when ingested.
The major components of commercial soybean-derived lecithin are:
-
33–35% soybean oil
-
20–21% phosphatidylinositols
-
19–21% phosphatidylcholine
-
8–20% phosphatidylethanolamine
-
5–11% other including phosphatidylserine
-
5% free
-
2–5%
-
1% moisture
Lecithin is used for applications in human food, animal feed, pharmaceuticals, paints, and other industrial applications.
Applications include:
-
In the pharmaceutical industry, it acts as a wetting agent, stabilizing agent and a choline enrichment carrier, helps in emulsification and encapsulation, and is a good dispersing agent. It can be used in manufacture of intravenous fat infusions and for therapeutic use.
-
In compound feed, it enriches fat and protein and improves pelletization.
-
In the paint industry, it forms protective coatings for surfaces with painting and printing ink, 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 , 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 also may be used as a release agent for , an anti-sludge additive in motor lubricants, an anti-gumming agent in gasoline, and an emulsifier, spreading agent, and antioxidant in textile, rubber, and other industries.
Food additive
The nontoxicity of lecithin leads to its use with food, as a
food additive or in food preparation. It is used commercially in foods requiring a natural emulsifier or lubricant.
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, such as with a high fat content of more than 75%, it stabilizes emulsions, reduces spattering (splashing and scattering of oil droplets) during frying, improves texture of spreads and flavor release.
In the EU Lecithin is designated at food additive E number.
Dietary supplement
Lecithin contains dietary precursors to
choline, an essential nutrient, which was formerly classified as a B vitamin (vitamin B
4).
Lecithin is a mixture of fats that contain phospholipids—including phosphatidylcholine, which makes up about 25 to 35 percent of lecithin—and the human body can convert phosphatidylcholine into choline.
Further, about 12 percent of phosphatidylcholine is already choline, so that choline makes up some 3 to 4 percent of lecithin.
Phosphatidylcholine is approximately 13.7% choline; as such, about 342 mg of choline is present per 10 grams of lecithin. Therefore, 10 grams of lecithin can be a source for the body to produce about the same amount of choline (342 mg) as can be produced by the body from 2 egg yolks.
Lecithin is generally recognized as safe (GRAS) by the FDA.
There is no robust, scientifically validated clinical research investigating the safety and effectiveness of high-dose lecithin supplementation in lactating women and their infants. A meta-analysis found no evidence that high doses of lecithin improved milk flow in breast-feeding mothers or infants, though concluded that "higher maternal choline intake was likely to be associated with better child neurocognition and neurodevelopment."
Soy lecithin does not contain enough allergenic proteins for most people allergic to soy, although the US FDA only exempts a few soy lecithin products from its mandatory requirements for allergenic source labeling.
A 2003 review of randomized trials found no benefit of lecithin in people with dementia.
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 Passover.
[(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 September 10, 2008.]
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 the 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.[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.]
Sunflower lecithin, sourced from the seeds of sunflowers, is entirely plant-based and may be an option for those with religious or cultural concerns regarding food intake.
See also
External links
