Dehydrated sorbitol fatty acid ester also known as sorbitan ester is a class of popular non-ionic surfactant, which has a history of nearly 50 years. Sorbitan ester has diverse applications in foods, pharmaceuticals, cosmetics, petroleum and other fields.
Since sorbitan esters are relatively hydrophobic, they are rarely used alone in formulations. They are usually used in combinations with other surfactants that have better water solubilities, which can exert better emulsification ability. Hydrophilic polysorbates are commonly paired with sorbitan esters. By combining different portions of hydrophilic and hydrophobic emulsifiers, different hydrophilic-lipophilic balances (HLB) can be achieved to expand the applications of the emulsifier mixtures.
Sorbitan esters are the non-ethoxylated precursor of polysorbates. Under the process of polyoxyethylene, transesterification occurs, where the ester groups on sorbitans rearrange and becomes polysorbates.
Like sorbitan esters, polysorbates are also non-toxic and are widely used in foods, pharmaceuticals, cosmetics, industrial formulations as emulsifiers, dispersants, defoamers etc.