What is lecithin?
Lecithin is the general and commercial term that identifies a group of substances whose colour varies from yellow to dark brown and whose consistency shift from solid to liquid. From the chemical point of view, lecithin is a mixture of phosphoric acid, choline, fatty acids, glycerol, glycolipids, triglycerides and phospholipids. Phospholipids do represent the main element.
Where is it obtained from?
Lecithin exists in nature in the animal and vegetable tissues and in the egg yolk. Indeed, its name comes from the Greek translation of egg yolk (lekithos means egg yolk in Greek).
It was Maurice Gobley, a French chemist and pharmacist, the first to isolate, to determine its chemical formula and to name this substance in the second half of the nineteenth century.
At the industrial level, lecithin is extracted from vegetable oils and from the egg yolk.
It is convenient to obtain it from soybeans since its availability is quite constant even if the lecithin content in the soybean is only the 0,5-0,6%.
What are phospholipids?
Phospholipids are molecules composed of a polarised hydrophilic head, highly water-soluble, and of a lipophilic body, non water-soluble. In the presence of water and fats, phospholipids arrange themselves between one molecule of fat and one of water, thus emulsifying the compound. From this characteristic arises the widespread use of lecithin as natural emulsifier.
What lecithin looks like at commercial level?
According to the law, when lecithin is commercialised for any technical use as well as a food additive, it is required that the phospholipid content is at least 60%.
How lecithin is obtain from soybeans?
The extraction process is concentrated mainly on the following steps: the cleaning of seeds that then are turned into “flakes”; the extraction of oil from these soybeans flakes and consequent refinery of the soybean oil. At the end of this procedure, water is added to oil so that the lecithin itself binds with the water thus separating from the oil.
What is the function of standardization?
After lecithin is obtained, it can undergo the process of “standardization”: different crude lecithins are mixed together thus to offer a final qualitative-optimized product, which responds to the purity parameters required by legislation and which self-maintain consistent and unchanged through time.
What is the HLB value?
The classification of emulsifiers is often expressed in relation to the hydrophilic and lipophilic balance, usually known with the acronym HLB (Hidrophilic – Lipophilic – Balance).
The emulsifiers are classified in a scale ranging from 1 to 20. Lipophilic emulsifiers have a low HLB value, while the hydrophilic emulsifiers have a higher number. The change between lipophilic and hydrophilic occurs at number 10 on the scale.
The properties of emulsions depend on the value of HLB:
Properties in Water:
Fields of application:
The HLB value helps to calculate the optimal mix of different types of emulsifiers.