Lecithin: Nature's Versatile Volatile Emulsifier

Lecithin was first isolated as an orange-colored substance in egg yolk. An important characteristic of this material was that it contained phosphorus, organically bound to a lipid-type structure. Industrial production of lecithin began when the Bollman extraction process enabled large quantities to be obtained from soybeans instead of eggs.

It took scientists a number of years to discover that the isolated chemicals weren’t uniformly structured, but were instead a group of chemically similar, but clearly differentiated, components that are now classified as phospholipids or phosphatides. Scientists also found that this class of chemicals is present in all organic tissue. All of these components can basically be called lecithin, but they may deliver entirely different functionalities in their individual applications.

The active components that all lecithins have in common are phospholipids. These consist of hydrophobic long-chain fatty acids counterbalanced with polar, hydrophilic phosphates. A concentration of phospholipids at the oil-water interface lowers the surface tension and makes emulsification possible. Once this occurs, phospholipids at the surface of the oil or water droplets form barriers to prevent the droplets from coalescing.

Industry employment

Lecithins are nature’s principal emulsifying agents. They greatly speed up dispersion of fatty and aqueous components in many types of food applications, including bread, biscuits, sweet pastries, convenience foods, ice cream, chocolate and margarine.

Confectionery. The most widely known and firmly established application for lecithin is in the making of confections, and chewing- and bubble-gum products. This natural ingredient improves the quality and eating properties of confectionery items and is used for both functional and process-technology purposes. Lecithin has a positive effect on form stability, allowing the addition of increased amounts of glucose syrup for shelf-life extension in chewing and bubble gum. It aids the binding of water in the chewing-gum mass, prolongs flavor release, extends shelf life, improves chewability, releases flavor and produces a fresher gum with enhanced smoothness.

In chocolate manufacture, such as chocolate bars and coatings, it reduces the amount of cocoa butter required, reduces viscosity and yield value of chocolate, improves flow properties, improves shelf life by reducing fat-bloom formation, and prevents sugar recrystallization.

Margarines. Lecithin also is commonly used as an emulsifier in the manufacture of frying, bakery, and diet margarine and spreads. Due to the bipolar structure of lecithin molecules, it helps reduce the surface tension between the oil and water phases. As a result, a homogeneous and fine distribution of droplet size can be obtained in spreads.

Bakery. In bakery products, emulsifiers can help reduce the rate of starch retrogradation—the process under which the starch molecules revert back to their original state as rigid crystalline granules—making the product stale. Emulsifiers also can work with lipoproteins to stabilize dough by forming gluten networks. In biscuits, crackers, pies and cakes, a 1% to 3% concentration of lecithin promotes fat distribution and shortening action, facilitates mixing, and acts as an “internal” release agent, which prevents the mixture from sticking to the pan, a major benefit for shape control.